INFORMATION TO USERS

This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted.

The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction.

1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)", If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity.

2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame.

3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete.

4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced.

5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received.

Xerox University Microfilms 300 North Zoflb Road Ann Arbor, Michigan 48100 MASTERS THESIS M-8394

HUDSON, Lucy GROWTH AND DEVELOPMENT OF CAPTIVE-BORN ORANGUTANS.

The American University, M.A., 1976 Anthropology

Xerox University Microfilms, Ann Arbor, Michigan 4sto6

Copyright by

LUCY HUDSON

1976 GROWTH AND DEVELOPMENT OF

CAPTIVE-BORN ORANGUTANS

by

Lucy Hudson

Submitted to the

Faculty of the College of Arts and Sciences

of The American University

in partial Fulfillment of

the Requirements for the Degree

of

Master of Arts

Anthropology

Signatures of Committee

Chairman:

Dean of the Colleg

Date

1976

The American University Washington, D.C.20016

THE AMÊEICM UNIVEKSITY LIBRARY GROWTH AND DEVELOPMENT OF CAPTIVE-BORN ORANGUTANS

by

Lucy Hudson

ABSTRACT

There is a present need for maintaining an orangutan population in research and education oriented institutions in the United States. There has been no success to date in breeding captive-born orangutans with one another and import laws are strict. Limited information is available on normal growth, development and behavior of orangutans in the wild and in captivity. A major problem is the evaluation of the experience and socialization necessary to enable captive-born orangutans to mate, produce and rear their young successfully enough to imprint traits of orangutan behavior that will aid in propagation.

Rare orangutan twins were subjects of a hand-rearing project and réintroduction program designed to promote independence, cage adjustment and orangutan socialization.

This study also made growth development and socialization data~available for future use. The method chosen for rearing produced unexpected behavior patterns and duplicated results of some experiments done previously using monkey subjects. PREFACE

Animal behavior studies, particularly those of primates, have enjoyed recent popularity. The general result is that where formerly an important scientific result might be reported once every five or ten years, such results have recently been appearing on a yearly basis. In the beginning, field studies of primate social behavior were undertaken by biologists such as Emlen, Southwick and

Schaller with inspiration from such physical anthropologists as Washburn, DeVore and Phyllis Jay. Due to the standard classical baboon field work, it became natural to think that most monkey and ape behavior and socialization must resemble that of baboons. Now with creative studies by Jane Goodall,

Hans Rummer, Dian Fossey and others who literally remain in the field for years to await results, we are witnessing enormous progress in recording natural behavior in the wild.

This particular study was very exciting and educational for those of us involved. We had no idea that orangutans did not develop as fast as gorillas or that reward stimulus does not work with orangutans as it does with chimpanzees. It was truly worth all the hours and frustration just to learn, first hand, how an infant orangutan grows up. There were also some very happy moments shared in observing new developments and in forming a warm

ii relationship with the nursery staff. During the time-lapse photography study the project was affectionately dubbed

"Clockwork Orang," a title that still remains in my mind whenever I view the film from that time period.

This study was aided by the Smithsonian Institution,

Washington, D.C. Cameras and equipment were supplied by both the Museum of Natural History and the National

Zoological Park. Film, processing and carpentry services were supplied by the National Zoological Park.

I would not have been able to conduct this study and prepare the manuscript without the assistance and cooperation of many people. I would like to express here, although all too inadequately, my most sincere thanks to them. Dr. Lucille E. St. Hoyme not only encouraged and stimulated my research into animal behavior, but also introduced me to the research staff at the National

Zoological Park. Whenever there were problems with availability and dependability of photographic equipment, she was resourceful, cheerfully cooperative and generous with her time and advice and even filled in the gaps with personal equipment to keep the project moving along. I am

indebted to Dr. John Eisenberg, Dr. Nancy Muckenhirn and

Judith Block for permission to carry out my research at the

National Zoological Park and to the Assistant Director,

Dr. Garner, for help in overcoming problems which arose. I am grateful to Dr. Charles W. McNett for guidance, patience

iii and sympathy through the final stages of preparation. My thanks are also due to Chris Borstel for assistance in setting up photographic equipment and for the pictures in the manuscript. Finally, I could not have finished without the help of Edith Repshis, my typist. I would like to express my appreciation to her for fast, accurate and very hard work.

IV CONTENTS

1 Introduction and Background ...... 1 Nonhuman Primates as Endangered Species ...... 1 The Orangutan as an Endangered Species...... 25 2 Basic Descriptive Goals of Study...... 32 Background History of Subjects and Program...... 32 Review of Techniques, Rationale and Methods .... 36 Experimental Rearing Conditions ...... 39 3 Early Experience in Captivity and Adaptation...... 45 Nursery — Weeks One Through Four ...... 45 Nursery — Weeks Five Through Eight ...... 53 Nursery — Weeks Nine Through Twelve...... 62 Nursery — Weeks Thirteen Through Sixteen ...... 7 2 Nursery — Weeks Seventeen Through Twenty ...... 84 Nursery — Weeks Twenty-One Through Twenty-Four . . 97 Nursery — Weeks Twenty-Five Through Twenty-Eight ...... 112 Cage — Weeks Twenty-Eight Through Thirty-Two . . . 119 Cage — Weeks Thirty-Three Through Thirty-Six . . . 122 Cage — Weeks Thirty-Seven Through Forty-Six. . . . 128 Cage — Weeks Forty-Seven Through Fifty-Two .... 131 Year Two — Significant Events...... 133 4 Growth and Development Patterns of Infant Apes. . . . 135 5 Behavioral Plasticity and Adaptability in Hand-Reared Nonhuman Primates ...... 171 Effects of Isolation on Primates...... 171 Maternal Deprivation...... 187 Disease in Captivity and its Effects on B e h a v i o r ...... 201 Learning Skills of Great A p e s ...... 20 9 Innovative Behavior ...... 221 6 Réintroduction and Rehabilitation of Captive and Displaced Orangutans...... 231 Relation of Réintroduction to Behavior and Ecology...... 233 Functional and Adaptive Advantages...... 252 7 Discussion and Future Considerations...... 257 Conclusion...... 257 Suggestions for Orangutan Rehabilitation at NZP and Current Primate Programs in U.S. Zoos. . . . 279 References Cited...... 279

V TABLES

I Significant Aspects of Development in Order of Appearance ...... 141 II Diet of Hand—Reared Orangutans 0-7 Months of Age. National Zoological Park, Washington, D.C ...... 145 III Dietary Additions for Hand-Reared, Caged Orangutans Age 8-12 Months. National Zoological Park, Washington, D.C...... 146 IV Comparison of Tooth Eruption Patterns in Four Hand-Reared Apes at the National Zoological Park, Washington, D.C., from 1-6 Months of A g e ...... 147 V Introduction of Poods to Two Hand-Reared Gorillas Age 0-14 Weeks. National Zoological Park, Washington, D.C...... 148

FIGURES

1 Smiles in Response to Tickling ...... 59 2 Clutching Action with Feet While Swinging and Feeding. . 67 3 Game of "Finger in Mouth"...... 70 4 Laughing Response During Game of "Finger in Mouth"...... 71 5 Play Responses ...... 73 6 Hanging from Overhead Bar with Feet Swinging Free ...... 83 7 Orangutan Clinging to Hair ...... 87 8 Orangutan Clutching Hair and Finger...... 88 9 Puckering and Kissing Behavior ...... 100 10 Response to Attention at Feeding Time...... 101 11 Puckering and Kissing Behavior ...... 102 12 Response to Hugging and Affection...... 103 13 Mimic Expressions...... 105 14 Reactions at Play T i m e ...... 106 15 Reactions at Play T i m e ...... 10 7 16 Orangutan Attempting to Hold Bottle...... 117 17 Food Intake Up to 22 Weeks of Age for Hand Reared Orangutan Twins at the National Zoological Park, Washington, D.C...... 149

VI 18 Growth Comparison on Infant Orangutans. Melati and Mewar, National Zoological Park, Washington, D.C., and Karen and Ken-Alan, San Diego Zoo...... 150 19 Comparison of Milk Consumption of Two Hand- Reared Gorillas at the National Zoological Park, Washington, D.C...... 151 20 Two Infant Orangutans; Head Circumference Measurements from 6-26 Weeks of Age (Mewar on R i g h t ) ...... 152 21 Two Infant Orangutans: Length of Head and Spine. Measurements from 6-26 Weeks of Age from Bregma to Sacrum (Mewar on Right) . . . 153 22 Two Infant Orangutans: Post-Cranial Measurements from Opisthion to Sacrum from 6-26 Weeks of Age (Mewar on Right)...... 154 23 Two Infant Orangutans: Chest Circumference Measurements from 6-26 Weeks of Age (Mewar on R i g h t ) ...... 155 24 Two Infant Orangutans: Upper Arm Length Measurements from 6-26 Weeks of Age (Mewar on R i g h t ) ...... 156 25 Two Infant Orangutans: Lower Arm Length Measurements from 6-26 Weeks of Age (Mewar on R i g h t ) ...... 157 26 Two Infant Orangutans: Upper Leg Measurements from 6-26 Weeks of Age (Mewar on Right)...... 158 27 Two Infant Orangutans: Lower Leg Measurements from 6-26 Weeks of Age (Mewar on Right)...... 159 28 Infant Orangutan; Comparison of Head Circumference (down) with Spine Length (across) from 6-26 Weeks of Age...... 160 29 Infant Orangutan; Comparison of Head and Spine Length (down) with Spine Length (across) from 6-26 Weeks of Age...... 161 30 Infant Orangutan; Comparison of Head and Spine Length (down) with Upper Arm Length (across) from 6-26 Weeks of A g e ...... 162 31 Infant Orangutan: Comparison of Head and Spine Length (down) with Lower Arm Length (across) from 6-26 Weeks of A g e ...... 163 32 Infant Orangutan: Comparison of Head and Spine Length (down) with Upper Leg Length (across) from 6-26 Weeks of A g e ...... 164 33 Infant Orangutan: Comparison of Head and Spine Length (down) with Lower Leg Length (across) from 6-26 Weeks of A g e ...... 165 34 Infant Orangutan: Comparison of Upper Arm Length (down) with Lower Arm Length (across) from 6-26 Weeks of Age...... 166

Vll 35 Infant Orangutan; Comparison of Upper Arm Length (down) with Upper Leg Length (across) from 6-26 Weeks of Age...... 167 36 Infant Orangutan; Comparison of Lower Arm Length (down) with Upper Leg Length (across) from 6-26 Weeks of Age...... 168 37 Infant Orangutan: Comparison of Lower Arm Length (down) with Lower Leg Length (across) from 6-26 Weeks of Age...... 169 38 Infant Orangutan; Comparison of Upper Leg Length (down) with Lower Leg Length (across) from 6-26 Weeks of Age...... 170

vxii Chapter 1

INTRODUCTION AND BACKGROUND

NONHUMAN PRIMATES AS ENDANGERED SPECIES

Use of Nonhuman Primates in America

According to statistics of the Institute of Laboratory

Animal Resources (ILAR 1968) the United States has become the largest user of nonhuman primates. Every year more than

200,000 live apes and monkeys are imported for pharmaceutical production and testing, biomedical research and amusement

(WHO 1971:167). In 1968 124,440 monkeys and apes were received from Latin America, Africa, Madagascar and Southeast

Asia for medical research, pharmaceutical purposes, zoological gardens and the pet trade. Individual surveys done over the past five years reveal that monkeys and apes have been used indiscriminately and that laboratories are not able to continuously replace the volume of animals used at a predictable rate. Within the last ten years scientists have become concerned as they have found it increasingly more difficult to obtain the numbers of primates needed for various programs. While imports fluctuate considerably from one year to the next there has been a noticeable decline in the figure since 1969 (Harrisson 1971:57). This reduction can be attributed to several factors: it may reflect a declining

1 need and capacity in the United States to continue research at the former pace; it may reflect a lack of funds for such research projects; it may also reflect disillusionment in the pet industry at the quality of the imported animals; and finally, it may indicate that American importers are curbing their tendency to overexploit these easily available resources (Harrisson 1971:57).

Medical research. A field in which nonhuman primates are playing an increasingly important role is medical research with good results. A great deal of medical knowledge has been acquired as a direct result of experimentation on them.

The Science Information Exchange indicates that there are 666 projects throughout the United States supported by Federal funds or local foundations in which primates are used

(Neurauter 1969:378). While it is not possible to give an accurate figure of the number of primates used each year to support these programs, a survey conducted by the Institute of Laboratory Animal Resources in 1965 indicated that the requirement was in excess of 64,000 and of this amount, only

2.2% were bred in this country (Neurauter 1969:378).

Several species of nonhuman primates particularly suited for use in biomedical research are declared vermin by local farmers. Consequently, there is no problem in trapping them for the primate reservoirs. One of the outstanding contributions of nonhuman primates to medicine is the development of the Salk vaccine for poliomyelitis (Harrisson 1970:66). Research on this began as far back as

1909, when Landsteiner and Popper discovered that polio can be transmitted to monkeys and apes (Moor-Jankowski and

Goldsmith 19 69). Polio vaccine is produced from fresh monkey kidneys, predominantly rhesus. During six years of polio vaccine development in the 1960s an average of 250,000 rhesus monkeys were imported to the United States each year, totaling a figure of approximately Ih million.

While the rhesus monkey, langur, squirrel monkey and chimpanzee seem to be the most popular animals in current medical research, no one species is the perfect primate for all kinds of studies. Therefore, research workers are not likely to restrict themselves to just a few forms (Conway

1966:286). Thus it may be pertinent to point out that medical research is inextricably bound up with the use of nonhuman primates as experimental hosts. In order to avert the decline in primate population, breeding in captivity should receive a great deal of attention.

Pharmaceutical research. The importance of nonhuman primates to pharmaceutical research can hardly be overestimated.

Because they are so like man in physique and physiology, primates occupy a place no other animal can fill (Conway

1966:284). The pharmaceutical industry imports large numbers of monkeys, as pointed out earlier, for the production of vaccines from monkey kidney tissue, as well as for drug testing. Rhesus monkeys are primarily used as donors of live tissue for the production of biologicals, while vervets are used mainly for toxicological testing of biologicals

(Harrisson 1971:57). The pharmaceutical industry is the major consumer of nonhuman primates because it has a commitment to produce safe drugs (Harrisson 1971:77). With the advance of medical research and the development of new vaccines, such as the measles vaccine in recent years, the pharmaceutical industry will, in all probability, continue to make ever-increasing demands for nonhuman primates from time to time. Because this industry is using natural resources and depleting them on such a large scale, it should commit itself to promoting alternatives such as contributing to the survival and the breeding of nonhuman primates.

Chimpanzees are being used avidly for research oriented toward producing an effective vaccine against hepatitis. Outbreaks of hepatitis that have occurred among human handlers strongly suggest that chimpanzees carry the human types (Harrisson 1971:67). The chimpanzee is a good subject for hepatitis studies because his normal liver values

(Kratochvil 19 69) and his hepatitic lesions are similar to those in man (Hartwell et al. 1968) . Some hepatitis antigens found in chimpanzees are " immunologieslly indistinguishable from the human prototype."

Nonhuman primates are also used for studies of the parasites and bacteria they have in common with man. They prove to be useful experimental hosts for studying the pathogenesis of amebic diseases in man in the absence of human test subjects in adequate quantities (Miller and Bray

1966). Previously nonhuman primates were used extensively

for malaria research, but this required the introduction of

artificial conditions. With malaria largely under control,

schistosomiasis has replaced malaria as a major concern of

the World Health Organization. Parasitic originators of

this disease may cause colitis, hepatitis, cirrhosis of the

liver and portal hypertensions, as well as pulmonary and

neurological disorders (Harrisson 1971:69). Nonhuman

primates are required to research the pathology of typhoid

fever even though typhoid immunization has been available

for several years. Chimpanzees are widely used in studies

of venereal diseases, partly because treponemal antibodies

were detected in free-ranging chimpanzees, suggesting that

the species is associated with treponesomes similar to the

human pathogen (Harrisson 1970:69).

Space programs. Because man places such a high value on his

own life, he often resorts to the use of nonhuman primates in

an environment where man's life may be jeopardized because of

planned or unplanned circumstances. During the earlier

phases of the space program, nonhuman primates, mostly

chimpanzees, were used to explore an environment which

constituted a great unknown hazard for man. To this end, the

Aeromedical Research Laboratory at Holloman Air Force Base,

New Mexico was established in the early fifties. This was

the beginning of the now famous sled rides of Col. John Paul Stapp, then the Man High Balloon Project; the ballistic and orbital flights of Ham and Enos, the Project Mercury

Chimponauts; and more recently, extensive laboratory studies of rapid decompression, toxic hazards, ionizing radiation, visual incapacitation, deceleration from high speeds, and the expanding of experimental medicine and neuroscience programs (Reynolds 1969:381).

Nonhuman primates are required for these programs because they can be trained to perform simple and complex operant tasks, owing to the integrity of their motor systems. In fact, the prime reason for using nonhuman primates as precursors for man is that they have a central nervous system quite like man's with hands that permit them to make fine tactual discriminations, as well as grasp, hold and manipulate objects within the environment. Moreover, these primates also have sensory systems that are very similar to man's which enables a study of auditory and visual functioning under extreme circumstances. This in turn provides some knowledge of what man would encounter under similar circumstances (Reynolds 1969:381).

Retrospectively, it must be pointed out that the experiments with man's nearest relatives were directly responsible for man's own safety in the subsequent manned space programs. Once man made his debut in space, the demand for nonhuman primates in this field was drastically reduced, and today the space program is a very small consumer of nonhuman primates. Amusement and education. There is a considerable demand for nonhuman primates in the field of amusement. There are a large number of zoos in this country and apes and monkeys are by tradition the most popular exhibits. Zoos across the country absorb only a very small amount of the nonhuman primates that are annually imported. Moreover, zoos breed enough of the smaller primates to furnish their own requirements and it is mostly the larger primates that are in demand. At one point, the insatiable demand for large primates like orangutans and gorillas Ijad led to a considerable amount of illicit trapping followed by illegal sales to zoos all over the world. This resulted in the realization that some of these species belonged on the endangered list and the depletion of wild stock should cease.

The Sarawak government, followed by others, took stern measures to stem this trade. Many of the zoos have cooperated in putting an end to the illegal traffic in primates due to scrutiny of purchase records and public pressure.

Before awareness and concern of conservation, museums sent expeditions to Africa and Borneo to collect skins and skeletons of chimpanzees, gorillas and orangutans in the name of natural science. This resulted in the crude slaughter of hundreds of apes simply for the purpose of obtaining a large number of skins and skeletons for museums. Dr. William

Temple Hornaday, who was chief taxidermist of the United

States National Museum, describes such a trip in his 1929 8 publication, Two Years in the Jungle. Fortunately, since the first half of the twentieth century there has been less killing for museum specimens although the killing of ape mothers to obtain babies for zoos continued.

Pet trade. It has been stated informally among researchers that approximately half of all primates imported from the

New World go to the pet trade. According to 19 68 statistics, this would suggest that over 29,000 primates were channelized into the pet trade (Harrisson 1971: 57).

The United States has the largest market for simian pets in the world dealing mainly in New World monkeys. Statistics indicate that by 1969 the import figure for the pet trade had declined to around 16,000 (Harrisson 1971:80). The pet trade is an "extremely competitive, high volume, low margin industry" (Cooper 1968) which makes the importer place maximum emphasis on a speedy turnover. The mortality rate for squirrel monkeys, which constitute between 70% and 80% of all monkeys traded in America (Harrisson 1971:81), is about 10% if they are held for less than three weeks, but rises drastically after that. Nutrition is largely a neglected aspect of the trade and a protein deficient diet is often administered, further augmenting the mortality rate.

Consequently, wholesalers lose no time in turning animals over to smaller dealers who in turn send them along to pet shops. The customer is lured to his potential pet through the use of very appealing advertisements, which provide very little information about the nature and disposition of the monkey.

It is not surprising, then, that the customer often ends up terribly disillusioned by his pet. A large proportion of primates die soon after sale because of inadequate maintenance and shipping conditions. Many of those that live on embark upon a traumatic period for both owner and pet. Imported primates become even more unsuitable as pets because of the potential disease hazard which threatens any individual who comes into contact with them. However, there are some advantages that result from individual ownership of pets. People who own rare, threatened or potentially threatened species such as gibbons, chimpanzees, uakaris and sakis are able to give more attention to their pets than most zoos can and may become particularly competent in rearing delicate species

(Harrisson 1971:83). If they are interested enough they can then make this valuable knowledge available to researchers and other people who are seeking it. Nevertheless, the disadvantages of the primate pet trade outweigh the advantages — irresponsible promotions of live nonhuman primates as pets cause many needless deaths and too many pets are offered and "rescued" by too many uninformed people

(Harrisson 1971:83). Serious pet lovers should be willing to sacrifice their individual interests in the general

interest of preserving the declining stock of nonhuman primates. 10

Entertainment. An unknown, but significant number of primates are held by individuals in the entertainment industry. It is often very lucrative to acquire a baby import, train it and then sell it as a performer later on.

Monkeys and chimpanzees are among the most uninhibited performers and competitions offering attractive prizes foster the use of primates as performers. Nominees for the

Patsy award by the American Humane Association often include some chimpanzees that have appeared in movies or on television.

Harrisson (1971:79) gives several psychological reasons for which man appreciates the entertainment provided by nonhuman primates: sometimes he simply admires the inventiveness and curiosity of the performers; at other times he watches them break the rules of society and the laughter that results brings relief from the pressures of everyday existence; more often man laughs at apes because they are our mental inferiors, and this helps to boost human egos.

The proliferation of the idea of recruiting primates for entertainment aids in the persecution of these declining species. The entertainment industry must recruit primates of a very tender age and the availability of captive babies poses another problem. In order to secure primate infants, the mothers usually have to be killed.

The use of nonhuman primates in America is thus both enormous and very diverse. All species of nonhuman primates 11 are potentially endangered, being threatened with depletion and extinction in the wild due to the activities of man

(Harrisson 1971:73). Aside from better breeding and conservation programs, careful attention must be focused on the species of primate being used for any particular program.

Maximum use must be made of individual animals in the course of research and above all, waste of primate life must be eliminated wherever possible.

Problems in Importing Primates

More than 200,000 monkeys and apes move every year in international commerce, but until recently, neither the consumers nor the veterinarian and medical authorities were overly concerned with the volume of international trade. The greatly increased use of monkeys in recent years, however, gave rise to a number of problems which made the authorities aware of the need for control over the trade and use of these animals. One of the major problems that became obvious is the rapid decline of wild stocks adversely affecting the

future supply of primates, particularly for essential medical purposes.

Depletion of wild stock. Nonhuman primates may well be

considered a natural resource that is being exploited with

very little being done to replenish it. Statistics indicate

that as many as 250,000 are used on a nationwide basis, but

only 1% of these are bred in captivity (Neurauter 1969:378). 12

Certain hazards, such as destruction of habitat and hunting for food and skins have long existed and are increasing. In recent years new dangers to the populations of primates have come to the fore: the needs of the pharmaceutical industry, medical research, zoological gardens and the pet trade

(Conway 1966:284). These recent demands have accelerated the pace of the decline of wild stock.

Surveys made by Southwick of rhesus and langur populations in India reveal sharp declines (Conway 1969:284).

In all likelihood, a similar fate awaits most other species of primates around the world. At best we can only resort to informed guesses on the magnitude of this decline based on the information provided by experienced collectors, travellers and naturalists. No foolproof methods have been devised by which scientists can accurately measure the rate of depletion of the population, particularly that of the smaller primates. While there is no accurate picture of the status of primate populations beyond very noticeable declines, we do have importation figures which reveal a large scale drain on wild stock (Conway 1969:284). The orangutan population has dropped to such a low level that exports have been completely banned. The extreme difficulty in purchasing specimens of other primates and the phenomenal prices charged are in themselves indicative of the dwindling populations (Booth 1969:387). But before discussing the

import depletion, we shall review the local factors that have 13 been responsible for decimating the primate population.

These are:

(1) Native hunters and trappers have drawn heavily on primate populations in search of meat and skins. While statistics are available to assess the extent to which imports are responsible for the decline in primate populations, it is much more difficult to ascertain the extent of damage inflicted by hunting and trapping. Primate skins have been world popular ever since the middle ages, but after the introduction of firearms into Asia and Africa, the slaughter of species took on massive proportions. This could only be vaguely estimated by the number of skins reaching the American and European markets. Laws have been enacted to prohibit this slaughter but they remain largely ineffective because skins continue to command high prices.

Besides, if neighboring countries are not concerned about enacting similar laws, skins can easily be smuggled from one country to the next and there sold legally. In Eastern

Africa, for instance, it is impossible to trace the skins of animals that have been caught illegally since a limited number come on the market legally each year enabling nearly all dealers in hides to have a number of legal skins to which they can refer (Harrisson 1971:14-16). Moreover farmers are permitted to kill primates which ruin their crops on the condition that they then turn the skins over to the Game

Department which also confiscates skins from illegal poachers.

These skins are then auctioned off to the highest bidders and 14

the purchasers are entitled to manufacture articles of

clothing from them. As long as this situation prevails, it

is almost impossible to stem the tide of illegal smuggling

of skins.

In many areas the primates are hunted by the native

population in search of food. This situation can be

remedied if the government is willing to provide alternative measures (Neurauter 1969:378). Hunting, in fact, is one of

the major factors that accounts for the decreasing population

of orangutans (Davenport 1967:248). The Batak tribe still

hunts the orangutan for its meat even though hunting has

been illegal for many years (Rijksen 1974:22). There has

been considerable pressure to supply the demands of foreign

zoos, but this has declined in recent years owing to the

efforts of the Survival Service Commission of lUCN. It is

heartening to point out that the Sepilok forest reserve in

Sabah, North Borneo is one of the best protected tracts of

primary lowland rain-forests remaining anywhere on earth.

Hunting has been forbidden since 1964 and the game branch of

the forest department has patrolled it to protect remaining

populations of orangutans, gibbons, and bears. It is, in

fact, one of the last sanctuaries of the orangutan (Fosberg

1969:339). By way of contrast, Cynthia Booth (1969:387)

points out that monkeys and chimpanzees are still legally

hunted for meat in Ghana.

(2) The extermination of crop raiding primates has

long been an accepted feature in any country that has a large 15 primate population. Some African countries have actually

embarked on primate destruction programs because the animals

are agricultural pests. Statistics indicate that a few years

ago nearly 25,000 guenons were destroyed in Sierra Leone by

farmers (Conway 1966:287). Primate research workers can

prevent this kind of large scale massacre by keeping

themselves informed about areas where governments are likely

to undertake monkey control. The offending animals can be

safely obtained and colonized elsewhere (Conway 1966:287).

The smaller primates are more often exterminated

than larger species as agricultural nuisances. In East

Africa, forest officials can write in to the Game Department

and request permission to shoot certain species of monkeys

(e.g., Colobus) if they are causing destruction to freshly

planted seedlings in the Forest Department's plantations or

to the standing crops of employees. Harrisson (1971:15)

states that once the Game Department gives permission for a

specific number to be shot, the situation invariably gets

out of control for the usually short-staffed departments.

The result is that the loss being permitted is several times

as great as that being prevented.

(3) The increase of forest clearing for human

habitation leads to the desecration of many primate species

through elimination of natural habitats. The world

population growth of more than 60,000,000 a year will create

the need to produce at least three times the present world

supply of milk and proteins by the end of this century. This 16 in itself is an indication of the agricultural intensification and expansion that must come if the world famine is to be kept at bay (Wayre 1969:4 7). Consequently, natural primate habitats are under severe pressure due to the spread of cultivation. Protection and control of forest habitats must come in advance of accelerated human development if endangered species are to survive. Emergency measures must be undertaken for gravely threatened species surviving in limited geographic areas. If the forests must be eliminated, some kind of reserves or parks should be set up to accommodate the resident primates.

A major threat to nonhuman primates, particularly the orangutan, is large-scale, mechanized logging of timber.

Dense rain forests are the natural habitat of primates as well as the most lucrative from the point of view of the logging industry. Logging provides revenue from timber as well as a network of roads on which more intensive hunting, agriculture, grazing of cattle and other developments proceed

(Harrisson 1971:9). In Malaysia, which boasts large rain forests as well as orangutan habitation, logging was prohibited by the British in 1954 so that 5,000 acres of untouched rain forest still remain. In recent years, however, industries owned by influential government officials have been pressing for the granting of logging concessions. These requests are not under serious consideration (Fosberg

1969:339). In areas populated by endangered species it is essential to link conservation with national forestry programs 17 and industrial planning along with the specification and promotion of essential reserve areas for primary forests

(Harrisson 1971:9).

(4) Inefficient methods of procurement for export have a drastic effect on primate populations. Increased demands for primates have resulted in unregulated and indiscriminate animal trapping. Unnecessary loss of primate life is geared to two factors -- inefficient methods of procurement and inefficient methods of export.

(a. Killing the mother is the easiest way of obtaining an ape infant. Since firearms are obtained with little difficulty and timber roads provide ready access into dense rain forests, orangutan infants are easier to capture than before. As with the other great apes, the method of getting a baby is by shooting its mother. The infantile mortality rate in captivity is extremely high — three out of four babies die before they ever reach safe hands

(Harrisson 1968:51). Young captured animals often die as a result of malnutrition, thus negating the purpose of the entire scheme in which two endangered primates have been sacrificed to no benefit. Illegally obtained primates which cannot be sold are killed for fear of confiscation by the government and subsequent penalties. This includes illegal trapping of smaller primates outside control areas and illegal methods of employing trappers without licenses. In areas where trapping is permitted, the Game Department requires that lactating females with young should be released 18 but this is rarely observed. This type of procurement is directly related to demands of purchasing organizations who place greater emphasis on infants and females (Booth

1969:389). This further impedes the likelihood of ape and monkey propagation.

(b. Inefficient export procedures waste a considerable amount of primate lives. Wholesale exporters derive their profits from volume rather than individual species sold. Statistics indicate that even in the case of the most robust species, for every one that reaches the importer in good condition four or five individuals die during capture and export (Harrisson 1971:5). Many deaths occur between trapping and export. Traps are too infrequently visited, animals are tactlessly handled, food and water is inadequate and animals are kept in poor and sometimes dirty temporary caging. With better care these losses can easily be averted, but the problems must also be viewed from a different angle.

The prices currently being paid for several species of primates are not adequate to allow for reasonable care of the animals in the interval between trapping and export.

Dealers claim that the profit margin per specimen is around two dollars (Booth 1969:389). Understandably, even a very small improvement in the care and handling of these animals would swallow up this profit. From the exporters viewpoint, it is probably cheaper to let an animal die rather than give it a single injection of penicillin that might save its life 19

(Booth 1969:390). Therefore, one way in which this tremendous waste of primate life can be arrested is by paying higher and more realistic prices. Price increases must be accompanied by an emphasis on better treatment for animals, however. Better still, purchasing organizations should offer a better price for specimens that are in better condition. This would attract traders who insist on higher standards and eliminate those who export specimens of poor quality (Booth 1969:389).

Losses in past years during transportation and at the port of arrival are said to have sometimes exceeded fifty percent (Conway 1966:288). New regulations as to cage size, the use of antibiotics and a better understanding of the use of electrolytes in dehydration are now contributing to an improvement in transportation conditions. Present trade economics, however, render individual action difficult particularly because major importers issue tenders to the lowest bidders. Improvements in current methods of acquisition holding and transportation must stem from combined efforts of exporters and importers. New standards and the legalization of all trade in wild animals and their products are urgently needed (Harrisson 1971:87).

Enforcement of laws governing import of primates. Thriving illegal trade was related mostly to gorillas and other large primates on the endangered list, particularly orangutans.

After World War II, a large-scale export, mainly unorganized. 20 brought hundreds of baby orangutans into the hands of animal dealers in Singapore and elsewhere in South East Asia. The

Sarawak government of Malaysia, followed by the Indonesian government, was the first to take serious initiative in stemming this traffic. Through the help of the Survival

Service Commission, most of the recipient countries concerned have cooperated in restricting or completely prohibiting trade in orangutans (Harrisson 1970:45). The purchase of

illegally exported orangutans by American zoos has been

effectively halted since September 1962, and several

European zoo associations have put similar self-imposed

restrictions into effect (Conway 1966:285). Some of the

small zoos still continue to present problems, though few

can afford the high cost and risk involved. The United

States now prohibits all imports of these and other

threatened primate species except under license (U.S. Dept,

of Interior 1970:72).

Health hazards to humans. It was only in the late 19 50s that

authorities recognized that primates presented a hazard to

public health. At that time international commerce in

primates increased considerably because of the development of

polio vaccines. Since monkeys and apes are so closely related

to man, they are especially useful for research on human

diseases. This means that they are also susceptible to many

human diseases which they contract readily. Poliomyelitis,

hepatitis, tuberculosis, measles and malaria are examples. 21

Moreover, many monkey infections can cause serious diseases

in man and apes (World Health Organization 1971:168;

Saenz 1969). One of the few documented cases of monkey transmitted disease was the 1967 Marburg tragedy when thirty

laboratory workers in Marburg and Frankfurt-on-Main contracted a severe virus disease from handling African

Cercopithecus monkeys. This virus proved fatal for seven of the workers (World Health Organization 1971:168). Another disease, attributed to Virus B, has been recognized in people handling monkeys and has resulted so far in more than twenty

deaths. An international committee investigating the Marburg

case recommended nine requirements to avoid similar outbreaks,

some of which were:

special arrangements to ensure that different monkey species do not come into contact during shipment; ideally that monkeys of the same species should not have contact if they come from different areas; all monkeys be regarded as potentially dangerous ; all monkeys be housed not more than two in a cage; that different monkey species should not be housed in the same room or in separate rooms connected by the same air conditioning system; that rooms and cages be sterilized between arrivals of different batches of monkeys (Hennessen 1968).

Many exporters consider some of these precautions unnecessary,

but the World Health Organization recommendations are designed

to reduce hazards to those who handle monkeys for laboratory

purposes. Thus, the potential health hazards to humans. 22 coupled with the stringent measures recommended to eliminate

them, constitute another significant obstacle to the import of primates.

Breeding in captivity. Maintaining sufficiently large populations of primates in the wild is the most economical way of ensuring their future supply (Conway 1966:287).

Therefore, great emphasis must be placed on the conservation

of endangered species by taking immediate steps to set up

captive and semi-wild colonies. For the vast majority of

species ecological investigation and the establishment of wildlife reserves are still future steps.

Replenishing wild stock deficit has assumed an

increasing significance in recent years. It must be

emphasized that the proper place in which to conserve a

species is in its natural habitat and that propagation in

captivity should be viewed as a last resort (Wayre 1969:48).

The use of wildlife reserves for breeding purposes is

becoming increasingly popular because of several advantages:

transport problems are eliminated; animals remain fully

acclimatized at all times; a breeding nucleus is kept in

safety where it can be effectively guarded while living under

virtually natural conditions (Wayre 1969:48). In this

context, the ultimate aim should be to release captive-bred

progeny in a suitable area in their natural habitat or

facsimile in order to reinforce the depleted wild population.

In the final analysis, maintaining adequately large 23 quantities of primate populations in the wild is the most economical way of insuring their future supply. It would reduce the tremendous wastage of monkeys that fall sick, are

ill-nourished or are injured or killed in trapping. In

short, breeding primates would decrease wastage and provide medical science with healthier and better animals (WHO

1971:168).

While zoos have pioneered the trend of breeding in captivity, they are unlikely to produce significant

surpluses for laboratory use. Moreover, in order to maintain their own stocks they will have to show fewer

species and maintain them in larger groups (Conway 19 66:

286). The "farm" approach has been successful in some zoos

and probably has much to offer laboratories, but thus far

neither laboratories nor zoos have scientifically,

systematically and experimentally varied breeding and maintenance conditions to determine the most productive

methods. We have yet to get young from a broad group of

species on a predictable economic and large-scale basis

under controlled conditions (Conway 1966:287).

Philip Wayre pointed out in 19 69 that captive

breeding programs do not necessarily have to be restricted

to conventional zoos and "the time may come when such

programs will be carried out in wildlife reserves" (Wayre

1969:48). Today, the National Primate Research Centers

Program, composed of seven regional research centers, is well

established and provides much valuable knowledge of nonhuman 24 primates and their maintenance in a colony environment

(Neurauter 1969:379). While these programs are not able to supply the requisite number of primates desired for medical and pharmaceutical needs the information they are providing is essential to future programs for they are contributing to the sum total of knowledge and skills necessary for the breeding and maintenance of these animals (Neurauter 1969:379)

When concern over declining primate populations is coupled with research requirements the obvious solution that comes to mind is breeding in captivity. Apart from preserving fast disappearing species, the breeding of monkeys and apes in captivity would eliminate many of the health hazards now experienced by those who handle them. A large number of monkeys and apes reaching laboratories do not meet health standards needed for refined research. Pathogen-free primates can be obtained only through sophisticated laboratory breeding (Van Bekkum et al. 1969) . The obvious advantage is that a captive-bred animal is a "clean" animal, of known age and medical history, acclimated to captivity and usually amenable to change and handling. On the other hand, it is socially underdeveloped because of the conditions under which it was reared, making it useless for many kinds of behavioral studies. Other disadvantages are the prohibitive cost of breeding primates in captivity and the fact that experimental work of any kind usually inhibits breeding altogether (Conway 1966:286). But, by far, the biggest 25 drawback to breeding primates in captivity is the lack of knowledge, for the biology requirements and behavior of primates varies from species to species.

The supply and value of animals used in research is largely determined by their state of health which can be greatly improved by breeding in captivity. This raises the obvious question as to which species should be given prior attention for breeding in captivity. The answer is twofold: those on the endangered list as well as those that are most valuable for on-going research programs. In short, animals

should be bred in captivity so as to produce healthier and better-defined animals (Moor-Jankowski 1970), but true conservation breeding needs long term commitment. A genetic base, sufficient to allow for selective mating, social

experimentation and population expansion, aimed at producing

the second and following generations, is required

(Harrisson 1971:79).

THE ORANGUTAN AS AN ENDANGERED SPECIES

Orangutans (Pongo pygmaeus) are long-armed, reddish­ haired, herbivorous anthropoid apes weighing up to 300

pounds. They are both gentle and intelligent. Their only

enemy, aside from an occasional leopard, is man.

Wild orangutans exist only in Borneo and on the

Indonesian island of Sumatra. No one really knows how many

orangutans still exist in the wild. In 1970 the calculated

number of orangutans in North Sumatra was 4,500 (Rijksen 26

1974:22). Like an ever-lengthening list of other animals, the wild orangutan is considered in danger of extinction.

In historical times the orangutan has been confined to relatively small jungle areas in Borneo and Sumatra.

Distributions in mature forests up to an elevation of 4,0 00 feet have been discontinued. There is archeological evidence that orangutans inhabited larger areas of Borneo and Sumatra and even extended into other regions of South East Asia as late as the stone age (Bourne 1974:354; Harrisson 1970:45).

The primary lowland rain forests in Sabah (Malaysia) form an ideal habitat for the orangutan, and it is extremely creditable that a newly independent state in one of the developing nations has shown the foresight to establish the

10,000 acre forest Reserve in Sepilok (Fosberg 1969:339).

During the period of British rule, logging was stopped in this forest in 19 54. 5,000 acres of untouched forest remain with 5,000 acres in various stages of regrowth. Despite this effort, one of the gravest threats to the orangutan population comes from the gradual destruction of its natural habitat. Indonesia’s forest exploitation policy involves the handing out of large timber concessions which now cover a great part of Sumatra's rain forest. These logged areas are usurped by cultivation which often deteriorates over the years into eroded grassy plains (Rijksen 1974:20). The tremendous increase in human population in this area

(doubling in the last fifteen years) has also been responsible for the destruction of the natural habitat of the 27 orangutan. The lack of sufficient arable land in the valley will soon force the natives to make "ladangs"

(shifting cultivation) in the reserve (Rijksen 1974:22). In short it may be pointed out that the logging industry, coupled with the dramatic growth of the human population in recent years, has been responsible for the destruction of the lowland rain forests that comprise the natural habitat for the orangutan population in parts of Malaysia and Indonesia.

Inevitably, this destruction of their natural habitat has resulted in a drastic depletion of this endangered species.

The free ranging orangutan is a difficult animal to study primarily because it is difficult to find. It is a solitary, silent animal and spends much of its time high in the dense canopy of primary forests (Davenport 1967:247).

The lack of numbers can be attributed to hunting and capture, mostly for export. As indicated earlier, the first serious attempts to eliminate this traffic were undertaken by the

Sarawak government shortly followed by the Sabah government farther north in Borneo. Both are now states incorporated in

East Malaysia (Harrisson 1970:45). The Indonesian government followed the example a short while later.

Moreover the recipient countries cooperated by refusing to import orangutans acquired by illegal means. This has considerably diminished the threat to the species from the aspect of hunting and capture, but the threat to its habitat still remains. 28

Until 19 50, no attempt had been made to rehabilitate orangutans back into the wild or to obtain essential information regarding the ecology and behavior of wild orangutans. The pioneer enterprise in this field came from

Barbara Harrisson who worked with the Sarawak Museum, taking baby orangutans that had been confiscated from Indonesian smugglers as well as the orangutan pets from native villagers and lumber camp timbermen and liberating them into the Bako National Park. Here they were studied in a semi­ wild state over a three year period {Harrisson 1970:46).

This pioneer venture was then carried further when it was transferred to a remote area in Sabah and is presently operated by Stanley de Silva, Chief Game Warden. Highlights of this scheme indicate that liberated young orangutans can be rejoined with wild groups, and even more significantly, an orphan female has bred with a wild male and has returned to have her baby in the control camp (De Silva 1972:104-105;

Harrisson 1970:46). Sometimes this program is not successful. Some orangutans have died, seemingly from the trauma of living between two worlds (theirs and ours) and some simply want to remain in the center waiting for mealtimes and playing with the wardens. It appears to be easier to create dependents than to make dependents independent again.

Recently, Richard K. Davenport, Jr. (1967) has conducted a study of orangutans in the Sepilok Forest Reserve and the Lokan River area, both in the state of Sabah, 29

Malaysia. He outlines several problems that obstruct an

intensive study of the orangutan. The study period is

relatively brief for it must be confined to the dry summer months immediately following the North-East monsoon when

jungle travel and search are easier; the primary forests with the largest concentrations of orangutans are the very

forests that are inhabited by a large number of elephants, wild pig, deer, snakes and an assortment of Bornean insects which can all combine to impede an intensive orangutan

study; also, the primary forests inhabited by orangutans are

often dense and impenetrable (Davenport 1967:249). Over and

above all these difficulties lies the problem of locating

the orangutan. As Davenport points out, "Hornaday in 1885,

and Wallace in 1869, found and shot numerous apes, whereas,

today even sighting one orangutan is a noteworthy event.

The older Ibans and Kedazans with whom I travelled had seen

only two or three in a lifetime." (Davenport 1967:248-249).

The studies of Davenport (1967), Harrisson (1961-

1971) and MacKinnon (1974) have given us considerable

knowledge about feeding, sleeping, nesting, vocalization and

response to intrusion of any kind, but has not furnished us

with any information on more complicated issues. General

social organization, dominance, infant care, sex behavior

and roaming patterns are still areas with unanswered

questions under intensive study (Davenport 1967:261). The

alteration of habitat and environment has a marked impact on

the social behavior of the orangutan. Because of diminishing 30 numbers of orangs in the wild, it is of utmost importance that such studies are undertaken as soon as possible. This goes hand in hand with needed behavioral studies of captive animals. With so many orangutans behind bars and no hope of replacement from import sources, we must find a way for these animals to breed and rear their young in a more natural manner. Artificial insemination is a big possibility (Rowlands 1974; Mortelmans and Vandenberg 1969) but it is an expensive way to replenish depleted stock.

Studies in the wild have not given us mother-infant socialization information and there are no published records of captive or wild-born orangutan growth and development information. At this stage captive orangutan growth and medical data could help the field worker recognize the age and progress of infants observed or help make health evaluations possible. Information regarding wild-born orangutans could be a great help in developing breeding colony plans. As yet, there has been no record of two captive-born orangutans successfully mating. It has been possible when one of the partners is wild born, however.

The study presented in the following chapters represents two orangutans mismanaged from infancy because of lack of information and experience on the part of everyone involved.

It will take many such studies of captive orangutans under different circumstances to even determine what is reasonably normal physical development, let alone normal behavior.

While laboratory studies of orangutans, or studies of them 31 in a semi-wild state are of considerable importance, they are no substitute for genuine field work. Experiences at

Yerkes Regional Primate Center indicate that orangutans become easily dependent on man, considerably molding their social behavior. Even the behavior patterns of orangutans in captive colonies located in the natural habitat differ widely from that of free-ranging orangutans (Davenport

1967: 262) . Chapter 2

BASIC DESCRIPTIVE GOALS OF STUDY

BACKGROUND HISTORY OF SUBJECTS AND PROGRAM

At the time Melati (Jasmine) and Mewar (Rose) were born, no thoughts of special ape projects had been entertained at the National Zoological Park,

Washington, D.C. The orangutan mother, Jennie, had successfully borne three previous infants and had reared two of them without help. She was expected to handle her new offspring as confidently as before. Both orangutan parents were wild-born and had exhibited no mating difficulties.

When Jennie produced twins on December 27, 1971, it was a newsworthy item. Orangutans normally produce one infant every three or four years in the wild and multiple births are rare. Orangutan twin birth had been recorded in captivity only twice before, once in Seattle and once in Munich. The actual birth was not observed and after discovery, the twins were left with Jennie on a trial basis.

Zoo officials were nervous over chancing the loss of two rare and expensive orangutans through maternal negligence or an accident. There was some question as to whether Jennie was producing milk. The infants had been observed nursing but the veterinary staff did not feel that Jennie's external

32 33 breast tissue exhibited enough enlargement for adequate milk production. This type of speculation was not based on previous experience as no records were available on the early lactation of orangutan mothers and no one could remember how Jennie had looked with her previous infants.

Human mothers do not usually establish an adequate milk supply until the fifth day after delivery or longer (Lyght

1966:1708). It was thought that an injection of Prolactin or lactation stimulation hormone might be helpful. However, the drugs on the market of this sort were for human use, had not been proven effective and required administration immediately prior to or after delivery, not several days after.

Human infants have survived five days without feeding before expiring (Fisher 1972:107) but zoo personnel did not wish to wait until the situation became critical. Finally after four days Jennie was tranquilized and the infants taken from her. She had been a gentle and protective mother but it was felt that the infants were showing signs of dehydration.

Previously the zoo had contracted the head ape keeper's wife to care for ape infants in her home until they were old enough to exhibit. This is a common practice of many zoos. A keeper, his family or a hired foster parent often takes zoo infants into a private home for hand-rearing and returns them when they can be exhibited with minimum care. (For descriptions of home hand-rearing experiences see every issue of the International Zoo Yearbook.) Although 34 this arrangement assured safe and conscientious hand-rearing methods, it was lacking many desirable features. No records were kept on ape growth and development, no practical methods were available for nutrition studies, ape to ape socialization was lacking, and the critical imprinting periods took place in the presence of humans in a home rather than around nonhuman primates or nonhuman animals in a zoo environment. These home reared infants were fed an exclusively human infant diet of commercially prepared formula and strained foods administered by means of spoons, cups, dishes and nursing bottles. They were never introduced to the types of foods an encaged animal receives for the remainder of its captive life or to the type of food most closely resembling that found in the natural habitat.

The zoo's hand-reared apes were always clothed, primarily in

Pampers disposable diapers, Curity baby undershirts and then cute, ornamented baby clothes for public appeal. The removal of these clothes upon entering the cage always represented a traumatic loss for the infant who had never been without them. Hand-reared apes of the National

Zoological Park slept in cribs and playpens with pillows and bedclothes, were bathed in a bathtub and shared a part of a human family life complete with television, automobile excursions, shopping trips, vacations at the beach and baby toys. Introduction to the cage was difficult from a physical as well as a psychological standpoint. No bedding of any kind, including straw or sacking is provided in the cages to 35

facilitate cleaning. Cockroaches and rodents run through all cages and over sleeping animals at night searching for

leftovers. Sights, smells, sounds, tastes and textures are

alien. Feeding and watering devices are totally different

from those used in a human home, not to mention the lack of play equipment, diversion and companionship.

The National Zoo had been considering opening up a

zoo nursery or special care unit designed to accommodate all

zoo babies in need of hand-rearing. This nursery would be

on zoo grounds having access to veterinary and medical

attention. The care and feeding could be monitored so that

dietary and exercise measures could be initiated and

enforced. The birth of the orangutans provided the

opportunity and incentive needed to try a different method

of hand-rearing. A temporary nursery was set up in a supply

room of the animal hospital located in the research building

of the National Zoological Park. This room was equipped with

good lighting, a sink, a floor drain and access to a stove

and refrigerator. A nursery director and staff workers were

scheduled for round-the-clock care and record keeping. The

twin orangutans and a baby African porcupine were the first

and only long term inhabitants of the new area. A baby

reindeer and a newborn lion marmoset were added later. Both

expired within 24 hours. A congenitally diseased giraffe

also expired before admittance. An incubator was kept ready

for five months awaiting the miscalculated birth of a gorilla

who never arrived in time to use it. 36

Aside from safely and hygienically hand-rearing the

ape infants, it was felt that positive steps could be taken

toward making them more adaptable and well balanced zoo members. The goals of the program were;

(1) Less dependence on human socialization and

more dependence on primate socialization.

(2) Cage adaptability without psychological trauma.

(3) Promote orangutan imprinting and ape

behavioral traits through réintroduction to

parents and other wild-born orangutan

residents.

(4) To aid in orangutan socialization to the

extent that breeding efforts become a

possibility rather than an experiment.

(5) To keep an accurate daily record of growth,

development, socialization and nutritional

data for aid in the hand-rearing of other

orangutan infants born at the National

Zoological Park.

REVIEW OF TECHNIQUES, RATIONALE AND METHODS

Subjects

Two infant orangutans (twins) from wild-born captive

parents, separated from their mother four days after birth

and maintained by foster care until parent réintroduction

(nine months of age) under conditions of partial social 37 isolation. These animals were supplied with a diaper for the first six months of life and resided in the zoo nursery where they could not see, hear or contact any other nonhuman primates except each other. During the periods of six to nine months of age they were placed in a cage in the

National Zoo's Small Mammal House which allowed them to see and hear monkeys and other animals but make no contact with either monkey or ape.

Apparatus

Living chambers — a playpen measuring 36x36x29 in. constructed for human infant use for the first six months of life. It contained a pad, a border and cotton flannel receiving blankets (white) for each infant. Later alterations included a mobile hung from the ceiling, a rope stretched across the middle for grasping, a wooden bar for hanging and a ladder inclined against the top rail, reaching down into the playpen.

The living quarters for the second phase of the study was a cage measuring 6x12 feet. It contained a ladder, a wooden platform with a small set of metal "monkey" bars, a wheel placed horizontally on a spoke which would turn, a water licker and a white receiving blanket for each

infant. The front of the cage was enclosed in glass for protection from public germs, the back and top were made of bars, and the floor and sides were concrete. 38

Third phase living quarters comprised a large cage in the Great Ape House with access to open air, bars on the ceiling and three sides, concrete slabs suspended from the wall for sleeping and a tire hanging from a chain for play purposes.

Photographic Equipment

Still pictures were made throughout the study with an Asahi Pentax Spotmatic and a Ricoh 126 Automatic. During the nursery stage the best results from motion film came from a Bolex 16 millimeter Cine camera.

Cage pictures consisted of still instamatic exposures and a time lapse apparatus set up for daily round-the-clock records. Fifteen different motion film cameras were tried in the cage. Out of these, the most successful cameras for this project were a GAF Super 8 (ST/602), Fujica Single -8

(Z2) and Honeywell Super 8. A Keystone time lapse box with attached timer made single frame movie film cover the appropriate time periods at one frame per minute. Batteries in the cameras, flash and time lapse equipment were changed daily as long term usage caused very heavy power drain.

Extra lighting was installed above the bars over the cage

ceiling to make night pictures possible. Outside pictures of

locomotion were made with the Fujica Single 8 and the Bolex

Cine cameras. These various types of recording apparatus were meant to replace the 24-hour human eye observation and 39 notes of the nursery phase and help pinpoint items or patterns unnoticed by the zoo keepers who were busy with their daily duties. Photographic methods such as those described by Gans (1969) or Rheingold et al. (1962:1055) using closed circuit television and earphones would have been ideal but were not practical from a financial standpoint.

Sound Equipment

Random vocal recordings were made during the nursery stage with an Akai X-1800 SD tape recorder and a Panasonic cassette recorder.

EXPERIMENTAL REARING CONDITIONS

The animals were to be cared for with a minimum of handling by a variety of people. Diaper changes, feeding, cleansing, weighing, measuring and medical attention were to make up the total personal contact from human to ape. No cuddling, fondling or carrying was permitted. This was meant to keep the infants from choosing any one person as a mother substitute or becoming too socially dependent on humans.

Since there were two animals of the same species and age involved, it was hoped that they would interact with each other successfully enough "during their developmental stages and be less dependent on humans for diversion and play.

The initial diet consisted of formula and commercially prepared strained foods for human infants. The National 40

Zoological Park had no guidelines for captive infant orangutan feeding. Yerkes basic diet for apes did not arrive until the infants were several months old and probably would not have been thought suitable anyway as it consists of a large amount of cereal. As the infants grew older, new foods that they might expect in the cage were

introduced to them. These included a variety of cheeses, raw fruits, vegetables and fresh bamboo.

As very young infants the orangutans were fed with a

tongue blade rather than a spoon and later they learned to drink commercial food directly from the container once the

lid was removed. Every effort was made to keep the infants

from becoming dependent on utensils and tools they would not

have in the cage. The nursing bottle with nipples seemed a

necessity and they nursed their formula in the manner of a

human infant, being held during the feeding and burped

afterwards.

Approximately six weeks before cage introduction the

lights were turned off at night to provide maximum sleep

time at night and activity during the day. The animals were

given more stimulus in the daytime in the form of day outings

and activity to keep them awake during the light hours and

make them more tired at night so that they would not become

frightened or lonesome lying awake in the dark. 41

INTEROBSERVER CONSISTENCY

Since daily, round-the-clock care and observation depended on a series of workers, confidence in the results is increased if it can be shown that the different observers produce consistent results. None of the nursery personnel had prior observational experience, research backgrounds or familiarity with primates. Many had experience with hand- rearing animals, mainly farm and country animals encountered by most children with farm backgrounds. These workers were instructed to note all elements of behavior observed regardless of how insignificant they might seem. All information regarding intake, elimination, weight and sleep were to be recorded along with the time the notations were made. They were also instructed to watch for physical changes and deviations in appetite, daily functions and development. Shifts were rotated to get a consistent view of daytime versus nighttime behavior. This turned out to be a good plan as the orangutans were less tense and ate better for some of the keepers regardless of the time. For others, they were not as cooperative and fidgeted so that they would be ravenous as well as overly sleepy for the following shift so that their behavior still seemed to be keeper-oriented rather than time or development oriented in many circumstances. Comparison of the notes and discussion among the various workers convinced me that the workers and I were seeing and describing the same elements of behavior. 42

First Phase — Nursery

Ail workers used the same equipment and same brands of supplies and foods. All new foods, toys and equipment were introduced in the daytime when there was more than one person present to record and photograph reactions. Visitors and workers from outside the nursery were kept at the barest minimum to cut down on germ spread and interruption of the routine. As strangers were unfamiliar to the infants, there was less success in feeding or socialization on visiting days

The infants would merely stare and not react. Each shift recorded notes in the same continuous notebook calling attention to items that seemed particularly outstanding.

Medical information and pertinent publications were read by all members and all procedure and schedule changes were posted in writing on a bulletin board as well as being relayed verbally.

Second Phase — Small Cage

Three nursery workers were transferred to the cage area to assist in general zoo duties as well as care for the orangutans. This was to help in recognizing new behavioral traits during cage adjustment and provide some continuity of familiarity to the animals. These three workers were still responsible for feeding the orangutans, cleaning their cage and providing exercise for them. Dietary information and amounts taken were recorded on a daily log sheet but it was 43 not possible to record hourly behavior elements as there were many other animals to care for. During this phase the time lapse equipment helped to confirm verbal behavioral reports and account for time spent in the cage. Weights and measurements were still possible as the animals were small enough to be handled and carried although they were becoming strong enough to make management difficult.

Third Phase — Large Cage

When the twin orangutans were placed in the large cage occupied by their mother, time film studies were not possible. The cage was too large to be covered by one or two cameras and the lighting was not good enough for day or night pictures. One familiar keeper went with the animals for feeding and random observation. Only daily visits and note taking were possible during this period of time as no one was hired to work in the area in the late afternoon or night. Still pictures with flash were possible during the observational periods although they interrupted behavioral sequences. Records of dietary information and amounts prepared were recorded on a daily log sheet. Most correlation of material was done by interviewing all workers who came into contact with this area and relying on the keepers' memories and verbal reports rather than reading observational notes. This was not satisfactory but was the only means to the needed information. 44

A total of 4 50 observational hours were spent on my personal study of the animals during one complete year of. life. Six months were spent in the NZP nursery located in the NZP Research Building, three months in the House of

Small Mammals and three months in the Great Ape House, both located in the main park area of the National Zoological

Park of Washington, D.C. Chapter 3

EARLY EXPERIENCE IN CAPTIVITY AND ADAPTATION

NURSERY — WEEKS ONE THROUGH FOUR

Appearance and Physical Condition

When the orangutan twins were received in the nursery the neonate pelage on both infants was sparse, approximately

Ih inches long and reddish brown in color. The hairs did not lie flat but stood individually with hair being thicker ventrally than dorsally. Hair on the head was longer than on any other part of the body. Fingernails were almond shaped and dark brown but the skin of the hands, feet, face and perineum were slightly lighter brown than the rest of the body. The genital region appeared swollen in both infants, undoubtedly as the result of maternal hormonal influence, but receded within forth-eight hours after nursery admission.

There were no remaining birth blotches on the face. Eyes were dark, unfocused and did not always move together.

Occasionally they would distinctly cross. For the first hours they were kept in an incubator at 80®F and then placed in a crib when it was determined that their condition was stable. Since the infants were nearly indistinguishable from each other, Melati was painted with gentian violet spots for identification purposes. This earned them their nursery

45 46 nicknames, P (painted) and UP (unpainted). Each person was required to sketch the nostril creases to further help in identification in case of a future mix-up. No fingerprints were taken. No blood was drawn to test for monozygocity or dizygocity. No one had looked for placental remains when the birth was discovered or to this day, ever even wondered or cared whether the twins were identical or fraternal.

When the infants were pulled from their mother it was decided that they were slightly dehydrated. A pediatrician was consulted for guidance. He prescribed a formula of Prosobee, a commercial milk preparation for human infants, to be administrated at room temperature. This formula was alternated with a mixture of Hypolyte and 5% glucose, an isotonic solution, for the first twenty-four hours to combat any dehydration present. The umbilicus was moist and unhealed. Under the pediatrician's orders,

Panalog, an antibiotic cream, was applied to the navels daily until healed (age 11 days).

There was some controversy over bathing the infants.

On the 12th day the twins were nearly totally immersed into a sink full of warm water and bathed with Ivory soap. The infants cried and made clicking noises but did not resist.

Since this bath was not part of the routine agreed on beforehand and was done by a volunteer worker, the pediatrician was consulted. He felt there was no need to bathe the infants until body odor became offensive. A partial bathing procedure for diaper changing was devised. 47

The attendants would cleanse the affected parts with wet or soapy cloths and rinsed thoroughly before dry diaper application. After feedings, faces and hands were wiped with a damp cloth. During the second week the skin on the face and hands began to peel. This is a normal occurrence in captive ape infants. Baby oil was applied to the affected areas and Vaseline to the genital regions.

In the normal newborn infant the first stools after birth are odorless, sticky, greenish black to brownish green. This fecal material is passed from eight to twenty- four hours after birth and is called meconium (Marlow and

Sellew 1961:90). The nature of the stools changes daily in the first week when the infant is nursing normally and assimilating his food. These stools are called transitional stools. From the third to fifth day they are loose, contain mucus and are greenish yellow. After the fifth day the nature of the stools depends on the feeding. The stools of a breastfed infant are yellow and pasty and have a rather pleasant, sourish odor. The stools of an infant fed on a formula of modified cow's milk are light yellow and hard and have a distinctly unpleasant odor.

When the infants were admitted to the nursery, a normal stool sample for milk analysis was not obtained. The first description on day four was of a "black meconium" stool. This may mean that the infants truly were unable to nurse for the first four days after birth. After six hours 48 in the nursery and three feedings, the stool was described as "grayish brown yellow with a few small curds." This sounds very much like the end of the transitional stage which normally ends on the fifth day and might mean that the infants were receiving nourishment after all. Odor did not become evident until the seventh day, however, and the stools still remained mostly dark in color with a few small curds.

Grasping

The clinging and grasping reflexes were so strong on both hands and feet that it was difficult to pry hands loose from even a few grasped hairs. The infants preferred to lie prone with a blanket to cling to. They appeared to become extremely agitated when turned on their backs, screaming loudly and tensing up their entire bodies until supplied with a rolled towel to cling to. For the first three days the twins were allowed to cling to each other during feeding, diaper changing and sleep. This arrangement was cumbersome, however, and it was discovered that if the infants were tightly swaddled in blankets they could be separated and left alone while attention was given individually.

Feeding

Feedings were every two hours on a schedule set by the pediatrician. This schedule did not seem to agree with the natural behavior of the twins. Many times the infants 49 were so sleepy that they appeared to sleep through much of the nursing period. Other times they gulped the bottle contents down hungrily and were not satisfied until more was offered. This early period of time might have presented an ideal opportunity to get the infants habituated to sucking on pacifiers. Material published when the infants were one year old (Brown and Pieper 1973) indicate that newborne orangutans engage in non-nutritive sucking as do human newborns and demonstrate a continuous sucking pattern on a pacifier. Previous hand-reared orangutans at the National

Zoological Park had become very dependent on pacifiers in their foster home and carried them into the cage at exhibition age. MacKinnon (1974:43, 59) who has published the most detailed report to date of orangutan behavior in the wild, has observed mothers carrying new infants in a ventral sucking position until the infant becomes strong enough to reach for the nipple from a side-ventral riding position. It would appear, then, that the zoo twins might have been satisfied by a pacifier and indicated hunger when the need arose. This might have put them on a feeding schedule that met their biological needs more realistically.

The pediatrician used the two hour feeding schedule as an indicator to how strong the formula should be. He left instructions to increase the strength of the formula if the infants should waken between feeding times and appear hungry

A pacifier might have been helpful in this analysis also, as the infants would not cry for milk if satisfied by the 50 pacifier between feedings. Later during the first month of life the infants began to exhibit thumb sucking and sucking on each other's mouths in between feed times. Hiccups became a problem and were never totally remedied. Orders were to burp the infants after the first draughts before the feedings progressed. The orangutans became successful in burping themselves all the way through the feedings but still had hiccups often.

Vocalization

Early vocalizations consisted of clicking, peeping, whimpers, soft hoots, fret noises, grunts and screams. All noises except peeping, clicking and grunting appeared to be distress calls indicating fear, hunger and insecurity or loneliness.

(1) Peeping sounds resembled those made by baby chicks. No particular action or behavior could account for this sound. It usually occurred when the infants were snuggled in blankets in their crib before or after sleep.

It sometimes occurred as they were sitting passively in an attendant’s lap.

(2) Whimpering occurred when the infants were separated from each other or their blankets in the crib or if one was left alone in the crib. It ceased when an infant was held, wrapped more tightly in blankets or placed next to the other infant. Sometimes the whimpering would cease if a nursery worker would shake the crib or pat the infant on the 51 back. There were times when many of these actions were carried out before the infant would cease the noise and go to sleep.

(3) MacKinnon (1974:63) describes soft hoots and whimpers as noises made by frightened infants. The exhalatory hoots become drawn out whimpers at higher intensity. This type of vocalization was described on the seventh day when a fuse blew, plunging the twins into a totally dark room for three hours. It took the infants

forty minutes to adjust and become totally quiet.

(4) Screams were also described as "screeches" by nursery personnel. Screaming occurred at feeding time when the twins were hungry and waiting for their bottles to heat.

(5) Fret noises seemed to be a mixture of the whimper and the scream. They might have indicated either hunger or frustration as they occurred when the nursing bottle was taken away before an infant was satisfied or if

an infant was placed on her back.

(6) During the third week a clicking noise was heard

during bathing or diaper changes. It did not involve any lip

action but was of internal oral origin.

(7) During sleep the infants would move arms and

legs about as they made a high pitched grunt sound. We did

not know if it represented discomfort or dreaming. 52

Vision

During the second week both infants appeared to notice some of their surroundings. Their eyes would move when approached by a nursery worker. They seemed to stare at close objects such as the crib wall or the face of an attendant. Mewar was thought to have followed a waving bottle with her eyes during the second week. The eyes still did not seem to focus well, would not always move together and continued to cross often. There was no blink reaction until the twelfth day when both reacted to the touching of their eyelids during feeding. During the fourth week the twins reacted to the flash of a camera. They had paid no attention during previous photography sessions.

Sleep

Sleep was very deep and occupied most of the time period not used by feeding. This was approximately 18-20 hours per day. The infants slept through slamming doors, telephone buzzers, fojrmula timers, autoclave alarms and the washing machine. They remained in a prone position clutching blankets with their hands and feet and occasionally

exhibited jerking movements of arms and legs accompanied by grunting noises. Mewar woke more often and earlier than

Melati and did not sleep for such long time periods. 53

NURSERY — WEEKS FIVE THROUGH EIGHT

Physical and Medical Problems

During the fifth week, unexplained respiratory tract symptoms appeared. Both infants began making wheezing noises during feeding periods. The veterinarian was present during feed times to listen to lung sounds and observe eating and respiratory patterns but could find no reason for the noise except for possible pharyngeal relaxation and excessive saliva. During the same period of time both infants exhibited occasional wet sneezing. Melati did this more often than Mewar and sounded more congested.

Fingernails became so long that Mewar ' s face was slashed and gouged in several places. Although this was the

National Zoo's first experience at cutting an orangutan's

fingernails, it proved no problem as the nails were soft and pliable. At this age the twins could be effectively restrained for the procedure.

During the seventh week the pediatrician came to

check the health status of the twins. Melati was undergoing periods of listlessness and occasional lack of interest in

food as well as continuation of chest wheezing. From the

appearance of her oral mucosa, fingernails and eyes it was

suspected that she might be anemic. However, the hemoglobin

on both infants registered 38% — normal.

The skin of infant orangutans appears to be quite

sensitive and reacts the way one might expect human skin to 54 react under identical circumstances. Since diaper changing was done only at feeding time, the orangutans spent a longer period of time in soiled and wet diapers than most human infants in an institutional situation might. It is difficult to tell if the periods of restlessness might have been partially initiated by diaper discomfort because no specific reaction indicating relief was noticed after diaper changing. It soon became evident, however, that special care was needed to prevent skin breakdown in the diaper area. Modern disposable diapers come with plastic backings to prevent leakage. This plastic also prevents air flow to the skin, increases heat and promotes an optimum climate for the growth of bacteria and fungus, particularly monilia.

When human infants wear cloth diapers, the addition of plastic pants creates the same problem, in addition to ammonia burn from urine decomposition. It was soon observed that the orangutans were becoming excoriated in the diaper regions and were in need of more thorough cleansing and lubrication at change time.

This problem would probably not have occurred in the wild or in a cage situation with maternal rearing. Ape mothers hold their infants, allowing excreta to fall free.

Genital areas are kept dry by free air flow.

During the eighth week a 24-hour trial period without diapers was initiated. The infants soon began to exhibit signs of ammonia reaction all over their bodies from contact with urine-wet surfaces. The flat mattress and blankets of 55

the playpen area made for impractical conditions for such

an experiment as there was no chance for drainage or

evaporation. Even though blankets were changed often and washed, the twins managed to rub the urine on each other as well as slide along ammonia-loaded areas.

Feeding became another problem. The attendants wore

rubber aprons to keep from becoming soiled but these aprons were so slippery, the orangutans were unable to cling into a

satisfactory feeding position. Feeding periods became

loaded with anxiety both on the part of the attendants and

the orangutans. Red rash-like spots developed on the chests

of both infants as well as raw areas as remote as behind the

ears and in the arm pits. This experiment was soon

abandoned as a useless method for preventing diaper rash.

The playpen environment was the cause of another skin

problem seen often in bedridden humans. Since both infants

remained in a prone position with little change of position,

pressure bearing areas became badly chafed and inflamed.

Melati, who was not as active as Mewar, was affected on

knees, elbows and the inner sides of her feet and on the

verge of skin breakdown. This would not have been a problem

if the infants could have been carried more or could have

had frequent position changes.

Oral Stimulation

During the fifth week both Melati and Mewar began to

exhibit signs of restlessness and agitation between feeding 56 periods. The infants were staying awake more and becoming alert during their wakeful periods. Since the attendants would not hold them, it was sometimes very exasperating to find some means of quieting them down. Crib shaking, back patting and blanket tucking worked at times and were ineffective other times. During the sixth week one attendant was able to have some peace by placing ticking clocks, watches and timers in the crib. When the objects were removed, the infants would begin to fret. When the tickers were replaced it would take approximately two minutes for the twins to become quiet again. Both preferred to sleep with a blanket or towel completely covering their heads and became agitated and distraught when it was removed.

Pacifiers were finally introduced to the orangutans during the sixth week. Up to this time they had sucked on fingers, hands and each other in between feedings. The nursery staff felt it might put an end to the fretting and agitation which seemed to be increasing on a daily basis.

At first introduction the orangutans had difficulty retaining them and keeping them from becoming malpositioned and sliding out of sucking position. When a pacifier was

dropped, an infant would place her mouth upon it and often end up sucking an edge or on the ring. After approximately twenty-four hours experience the twins began to attempt to

use their hands to keep the pacifiers in place. There was

no preference over right or left hand. The twins seemed to 57 experiment by pulling the pacifier out of the mouth and sucking it back, chewing or gumming it or attempting to push it still further in than its ring would permit it to go.

During a wakeful non-hunger period, sucking and manual manipulation of the pacifier was observed as well as quietly holding it in the mouth with no suction. The infants seemed to be quite dependent on it for sleep purposes. They fell asleep faster and more quietly with the pacifier in place but awakened often as the pacifier began to slip out of the mouth. There were still frequent times when the infants remained restless and agitated and rejected the pacifier as a comfort object. The pacifiers were ineffective around feeding time when the infants were hungry.

During the second month the behavior attached to true hunger became more pronounced. Crying became intense, shrill and persistent. When the twins were side by side, they would clutch and mouth each other and suck the heel of the hand, a rattle, blankets or the attendant's arm. Exaggerated lip pursing, lip puckering and chewing motions were made.

When one infant was fed first, the feeding sounds would cause the remaining infant to shriek loudly and attempt to crawl in search of comfort. During the eighth week, lip smacking was observed during feeding periods. 58

Socialization

During the seventh week Melati began to react to external social stimulus by changing facial expressions and vocalizing. When tickled behind the ear by an attendant, she wrinkled her face and raised one corner of her mouth in a half-smile (Figure 1). At the same time gasping chimp­ like noises were made. During the same week the infants began to pay attention to each other in a manner that might be interpreted as play. They touched each other with hands and mouths and mouthed each other. On two occasions, Mewar pulled Melati's hair to such an extent that Melati cried until finally released. In the course of the seventh week the orangutans exhibited one fifty-minute nonvocal period in which they quietly moved, explored the crib area, looked at hands and arms and mouthed the blankets. Attendants removed blanket fluffs and lint from the orangutans’ mouths when chewing-like motions were observed.

Development and Motor Skills

During the second month we did not see as much progress as we had expected. The infants became stronger,

Mewar showing more signs of strength and aggressive behavior than Melati. The crawling motions that had developed during the first month evolved into a crab-like crawl. Aimlessly, the twins could travel if they flailed their arms and legs and pushed along with the legs and feet. Again, Mewar was 59

Figure 1. Smiles in response to tickling. 60 much better at this. She could eventually travel three quarters of the way around the playpen until she bumped into her sister. Melati travelled short distances but did not make as much progress and did not have the stamina to exercise for such long periods of time. By the end of the eighth week Mewar had still never turned from a prone to a supine position. Melati had done it twice during the first month but it had not been demonstrated since the fourth week. All observers thought the first two turns might have been accidental as no one had actually seen her do it. On day 47 (week 7) Melati turned on her side while crawling and began to totter as though she would complete the turn to her back. At this point she screamed very loudly and fell back onto her abdomen.

At the end of the eighth week of observation all of us concerned with studying the progress of the twins began to wonder if they were, in fact, developing normally for their species. After studying publications on gorilla

development (Carmichael, Kraus and Reed 1961; Rumbaugh 1967;

Lang 1961; Knobloch and Pasamanich 19 59 a and b; Kirchshofer,

Fraderich and Podolczak 1967 and Kirschofer et al, 1968) it was evident that we could not judge orangutan development by

gorilla development patterns. Orangutans were naturally much

slower in some very basic areas. For instance, the gorilla,

Tomoko (Carmichael, Kraus and Reed 1961) had three teeth by

the end of the first month and a total of eight by the time

he was two months old. This developmental feature could not 61 be expected to alter with variations in early social experience but might be altered by nutritional deficiencies or a medical condition. The orangutans were being fed basically the same diet as Tomoko and physical checkups showed them to be medically sound. At the end of two months, gorillas are sitting up, pulling themselves up on chair arms, pushing up on all fours and rolling over well.

None of the observed behavior of the orangutan twins remotely resembled progress along these lines for the same age.

It appeared that the orangutan development pattern resembled chimpanzee development for the first month of life

(Riesen and Kinder 1952). However, by the end of the first month a chimpanzee is strong enough to roll from a prone to a supine position, more than the orangutans could do by the end of the first month.

It would be natural to expect orangutans to develop faster than a human infant since they are much stronger at birth and since all apes and monkeys documented have developed faster than human infants normally do. It appeared that the orangutans were stronger in the manner of grasping, clinging and holding their heads erect. For the first month they had been approximately one week ahead of the norm for human infant development but during the second month they appeared to be in danger of falling behind. At the end of the second month a human infant is able to follow a moving light or object with his eyes, can turn from his side 62 to his back and has begun to show the beginning of social behavior by responding to smiles with smiles and listening to a speaking voice (Marlow and Sellew 1961:258). Although the infants seemed to be keeping up with human infant development on an exact time basis, Mewar had never turned, never responded socially to an attendant and was unable to follow a moving light with her eyes. Melati had just begun to do these things. At this point, doubts as to the degree of normality in the behavior or development were voiced to the Chief Veterinarian and the Vice President of the National

Zoological Park. It was difficult to believe that Melati and

Mewar could be mentally retarded but everyone felt that, for some reason, the beginnings of developmental retardation was evident.

NURSERY — NINE THROUGH TWELVE WEEKS

Clinging Response

Melati and Mewar had strong grasping reflexes at birth and continued to "clutch" blankets, laboratory smocks and hair during sleep and feed times. As the infants grew older, however, it became apparent that they could not support their weight when clinging by themselves. It must be remembered that up to this time the infants had no stimulus except that initiated by each other and the attendants during feeding time. Since they were handled only at feed time, there had been no opportunity to encourage exercise and play 63 periods. Aside from the baby porcupine, there was usually only one quiet attendant in the room, leaving much to be desired in the way of visual and auditory stimulus. Nursery workers had assumed that the infants would take care of their own exercise needs by crawling and wrestling as they became stronger. What was overlooked, apparently, was proper exercise and maintenance of muscles needed for clinging, climbing, swinging and ape locomotion in general.

Up to this time the infants had lain in a position assumed by Western human babies. The flat, horizontal mattress and limp blankets could, in no way, compensate for the normal vertical hanging exercise needed by an orangutan baby.

Zoo personnel had become accustomed to watching baby monkeys cling to their mothers from birth until weaning time without difficulty. No one suspected that the clinging response might be a learned skill, essential to arboreal infant survival. The attendants had never studied the beginnings of clinging closely enough to see monkey mothers supporting infants until they could become strong enough to cling securely on their own. The foster mother who had hand-reared other ape infants for the National Zoological

Park, including an orangutan, stated that none of the

infants had been able to cling without being taught and that practice periods were required until they could initiate it themselves. This agrees with the findings of McCullock

(19 39) in his studies of clasping activities of chimpanzees. 64

By the tenth week {2h months) it was felt that the orangutans would have demonstrated natural clinging if it was truly an innate developmental. Dr. John F. Eisenberg, a specialist in primate behavior, was consulted. Dr. Eisenberg was currently doing research with spider monkeys at the

National Zoological Park Research Building. After observing the orangutans, he advised the nursery director, and the

Director of the National Zoological Park that primates without mental and physical stimulation do not develop normally and exhibit muscle atrophy. He suggested that the infants be introduced to clinging exercises to build up the muscle response needed for grasping, clinging, climbing and swinging as well as normal ape locomotion. He stated that in his experience with monkeys without stimulus, he had seen muscles atrophied to the extent that full range of motion was never achieved. The Assistant Director of the National

Zoological Park, a veterinarian, advised the nursery that animals that cannot exercise properly are not able to lay adequate calcium deposits on their bones, therefore prohibiting development to their full physical potential.

He felt that clinging exercises would help and that additional opportunities for grasping and clinging should be made available in the crib situation.

A rope was stretched across the playpen in hopes that the orangutans would learn to clutch it and use it as a

locomotion aid. It was difficult to introduce the infants

to the rope since they were not used to clinging for support 65 and were uncomfortable in any unaccustomed position. The attendants attempted to place the infants' hands on the ropes but could not get them to cooperate by making any grasping motion. The orangutans lay directly under the rope where they could see it and reach it but could not become interested enough to touch it unassisted.

A second exercise involved placing the twins in a sitting position and placing their hands on the rope.

Neither had developed the ability of sitting unaided and needed the rope for support. Instead of providing support, the rope was too flexible and slack for steady posture maintenance. The infants either fell forward onto the rope and mouthed it or fell back, still hanging on the rope, screaming until they completed the fall and loosened their grasp.

Pillows were placed upright in the crib against the bars and the orangutans were placed on them in a sitting position with hands and feet supposedly clutching the pillow in a ventral clinging position. Both infants feebly tried hugging the pillows uneasily and ineffectively using arms and hands only, gradually slipping down until they reached their accustomed prone position.

Whenever the twins were placed in the playpen after feeding, they were positioned next to the vertical bars on their sides with hands and feet placed on the bars. This was an effort to suggest casual, frequent grasping for hand and foot coordination. An attempt was also made to place the 66 hands on the top rail of the playpen, forcing the orangutans to maintain a pillow-supported sitting position. All of these crib-oriented exercises were met with disinterest, lethargy or sheer panic. At no time would an infant take hold of an object needed for support and close a hand or foot around it.

It was decided that vertical cling exercises should be administered for five minutes at every feeding time.

There were no attendants who were experienced in transporting clinging orangutans about the room. Each attendant devised and experimented with methods that kept the orangutans clinging as well as possible with a minimum of panic. The attendants wore loose laboratory coats to facilitate clutching. Some of the attendants wore a towel around the neck with the ends hanging in front, some wore towels around the waist for foothold aid, some stuffed the pockets with towels and some encouraged the orangutans to take a thumb hold and swing from the upturned thumbs. The infants could cling for only two minutes at best, showed no initiative in unaided clinging and appeared to be terrified throughout the entire exercise. Feet were usually clutching each other, flailed backwards or dangling (Figure 2).

Although the attendants repeatedly placed the feet in a stable clinging position, the infants did not seem to understand enough to maintain the position and would begin to scream as they slipped. 67

Figure 2. Clutching actions with feet while swinging and feeding. 68

It was found that the sessions were more effective

if an attendant would walk around the room while encouraging the twins to cling. The orangutans then seemed to become interested in their surroundings, scream less and show less apprehension. Melati became distracted easily, would let go with one hand and then become terrified at finding herself hanging by one arm. Even by the end of the third month, neither infant was strong enough to cling for an entire five minutes without slipping or tiring. Attendants kept attaching the feet to clothing and pockets to condition the clinging responses of the feet but the orangutans would always clutch their feet together instead of reaching out with the feet for a stable position. When the infants were placed in a sitting position, a towel was placed between the

feet to introduce them to the feel of materials that could be clutched and to keep the feet separated, prohibiting foot

clutching.

During the twelfth week one attendant had an idea

that proved to be worthwhile in making progress. He placed

a broomstick across the crib rails next to the rope. Since

this object was much more stable than the rope, the infants were not as uneasy with it. The broomstick became a

permanent part of the crib and was mounted in such a way that

it could adjust to different heights. 69

Summary of Overall Development

Aside from clinging activities, nothing really new happened during the third month. The infants appeared to be on a developmental plateau as well as a weight plateau.

True food rejection behavior appeared with the infants pushing new solid foods out with their tongues, grimacing at new tastes and spitting out what they did not want to eat.

The pediatrician recommended more protein in the form of egg yolks and meat which the infants seemed to detest upon

introduction but eventually ate.

The vocalizations remained the same except that they were louder and more frequent. Both Melati and Mewar had begun to make chimpanzee-like chuckles when being tickled but only one attendant (who had had experience with chimpanzees) could get them to respond to her with this

noise. Mewar became disturbed at the noise of a Macaw who was a patient in the clinic next door and began chirping back at every squawk the bird made. This was her first

introduction to a zoo noise. Rumbling hoots were made for

hunger, chirp noises during pacifier mouthing and soft cries while being washed with running water.

During the twelfth week more indications of play

behavior appeared with Mewar being the most responsive.

Mewar began to nibble and bit the fingers of the attendant

(Figures 3 and 4) , a game attendants termed "finger in

mouth". She responded in breathy laughs or chuckles when 70

Figure 3. Game of "finger in mouth." 71

4-1 3 e

*4 (U en C •H M -l tM 0

1bi C •H

•ay 0) en a o Uia o (4 tr C •H tr» 3 (d

0) tr •H 72 air was blown into her mouth and began waving her arms about

(Figure 5) and running her hands over the back of her head during play periods. The infants began trying to crawl to each other in the playpen and seemed to want to make physical contact with each other. This often resulted in so much hair pulling that the attendants felt the need to separate them. During this week we saw the beginning of ventro- ventral contact in its earliest stages. Although we didn't know it at the time, it was to be a major and controversial issue throughout the first year of life for the orangutans.

NURSERY — THIRTEEN THROUGH SIXTEEN WEEKS

Development and Exploratory Behavior

Clinging exercises seemed to arouse an awareness of capabilities in the twin orangutans. During the thirteenth week some weak attempts were made toward foot grasping. The infants began to reach out with their feet for loose pockets or towels when carried about. On several occasions the infants would spastically pull themselves up on the bars or the rope and find themselves hanging free with feet clutching tightly together. This type of experience would bring on terrified screaming until rescued. The same response would happen when the twins were sitting, supported by the rope and fell backwards. In spite of the uncoordinated actions and apparent fear, the twins seemed to be stimulated enough to stay awake more, look around at their surroundings and move about more than they had before. 73

Figure 5. Play responses. 74

The fourteenth week saw a burst and acceleration of new accomplishments and self confidence. The infants were reaching out on their own to grasp and handle whatever they came into contact with. They handled each other, the crib bars, ropes, broomsticks and even reached through the bars to touch the attendants' bodies as they walked past or sat close to the playpen. After several attempts at spontaneous grasping, the infants began to experiment with clinging and what they could do with it. They began to pull themselves up into sitting, kneeling and standing positions. After the initial surprise at finding themselves in their new positions, they would repeat the actions over again until their activities began to resemble "chin ups," "sit ups," and "stand ups" in slow motion. Stamina and coordination still left much to be desired. Melati could support herself on a crib rail for only one minute and Mewar was good for two. In the clinging exercises initiated by the attendant, both Melati and Mewar became relaxed and even casual, enjoying the contact. They learned to adjust their hands and feet for support, move their bodies about for a better view or to reach out for something in the room and later became

so casual as to dangle by only one arm while waving the feet and the other arm in excitement. Day by day we could see

increasing ease over assuming new positions under different

circumstances. Attendants could hold the infants upside down with a minimum of reaction on the part of the orangutans

The twins were placed upside down with their feet clutching 75 the broomstick and their hands on the playpen floor and they exhibited no fear. Before, flipping over to a supine position or being placed in a supine position would bring about frantic, uncontrolled screaming. Now, four out of five times, the twins could lie quietly on their backs, waving their arms about or simply observing the mobile over the playpen.

The feet became more coordinated, strong and helpful during the fifteenth week. The twins began to handle their feet, reach out for the bars with them and occasionally put one in their mouths during feeding time. Although there was still a great amount of foot to foot clutching, the infants were beginning to reach out with individual feet and cling to different objects and materials with ease.

By the end of the fourth month, Melati and Mewar were noticeably stronger, more confident and more coordinated in locomotory activities as well as clinging.

Mewar, still the stronger and more aggressive of the two, had built her standing time up to ten minutes when supported by the playpen rail. Melati was up to five minutes at this time. The floor of the playpen was lowered four additional inches to give the twins more standing and reaching space.

The orangutans were able to reach out at will for an offered object, make contact with it and carry it back to the mouth without dropping it. They were introduced to some stimulating playthings: shiny jar lids, balloons, and pieces of knotted rope were hung under the mobile on the bar 76 across the playpen. A red, hammer-shaped rattle was also given to them. Instead of being curious or enthusiastically playing with any of these objects, they acted uninterested, indifferent and bored around novel toys. After the objects had been in the playpen for awhile, a slow introduction would take place. Once and awhile an orangutan would stare at the toy and then look at something else; later she would touch it with her mouth or reach out with a finger or a foot and then, sometimes even days later, we would observe the animal playing with the object. Melati and Mewar became interested in their surroundings and aware enough to notice that there was activity outside the bars of the playpen.

Before this time they had turned toward noises in the room but had not looked for the origin. Now the twins were actually moving up the bars of the playpen, raising their chests and heads above the mattress while clinging to the vertical bars, and watching whatever activity took their fancy. During feeding time, the twins would watch each other being fed and vocalize occasionally. Sometimes they would reach out through the bars and wave their arms or touch an attendant and sometimes they would protrude the whole head through the space between the bars.

Infant to Infant Socialization

The orangutans seemed to have two types of contact with each other. The first type which was termed "wrestle play" had been steadily developing since the first month in 77 the nursery. It was an easy-going type of contact activity in which the orangutans clutched each other's body, mouthed each other, pushed against one another and moved about each other's body while touching, sucking or grasping. There was little vocalization and a minimum of stress attached to this behavior. The worst thing that could happen was intense hair pulling in which one or both infants seemed to forget that she had a handful of hair from the opposite partner and would attempt to change position or move on.

This caused persistent screaming from one or both animals and the attendants would feel compelled to separate them.

During the wrestling periods the orangutans would often share a pacifier, passing it back and forth, and mouth each other's face, particularly the mouth. They often pulled on each other's diapers, sucked on the diaper pins and sucked the knees, toes and heels of the opposite partner.

The other type of behavior was disturbing for the attendants to watch as it was more forceful and more violent. The notes of one attendant describe it as "almost predatory" and he was "shocked" when he first observed it during the fourteenth week of development. One infant, usually Mewar because she was the strongest and exhibited more signs of aggression, would reach out to clutch her partner. This usually happened when the partner was unaware and entertaining herself on the rope, bars, rail or some other piece of exercise equipment. The aggressor would grasp a handful of hair and pull her sister down from a 78 standing or sitting position to a supine position. The aggressor would then lunge on top, pinning her sister down and begin strongly sucking her face. (The attendants called this "devouring" as it seemed descriptive of the purposeful and compulsive manner of the sucking.) The victim was never cooperative in this interaction but always screamed and flailed until rescued. This type of behavior was observed three times during the fourteenth week, twice during the fifteenth week and three times in the sixteenth week. By the end of the fourth month, both infants had bruises on their faces and bodies from the intensive sucking and Melati had a deep scratch in the corner of her eye.

Infant to Attendant Socialization

One attendant found it difficult to keep from handling the infants and usually played with them more than any other person. Both infants responded to tickle play by laughing, smiling, waving their arms about and squirming into good tickle positions. There were times when she would stop and the twins would initiate further tickling on their own by waving their arms or reaching out to touch her for more.

The twins had begun to make breathy, chimp-like laughing sounds for other attendants as well during play periods and loved to play "finger in mouth" after feeding periods.

During this game, the infants would hold onto the attendant's finger, pulling it into the mouth. The attendant would respond by tickling the roof of the mouth and wiggling the 79

finger about. The orangutans would mouth the finger and try out different mouth positions over it. Whenever the

finger was removed, an orangutan would try to capture it and either hold it down and reach for it with the mouth or pull

it to the mouth with her hands.

During the fourteenth week the infants began

screaming for attention. This was tested by leaving the

room during an infant's tantrum and observing, unseen,

through the glass window in the door. In every case, when

tantrum-like behavior was suspected over hunger or physical

discomfort, the animal would cease screaming shortly after

the attendant left the room but start up again as soon as

she could see the attendant come through the door into the

nursery. These tantrums stopped immediately if the infant was picked up and carried about or cuddled in any way. The

twins did not throw tantrums together, but individually,

Mewar's reaction being more intense and lasting longer.

During the fourteenth week Mewar became so upset as to hit

her head against the bars of the playpen repeatedly. Her

screaming was so uncontrolled that her face became

purplish-maroon in color and contorted. Mewar's tantrums

usually lasted approximately two full minutes; Melati could

hold out only for one minute. The nursery decided, at this

point, that the tantrum behavior could not be rewarded with

attention as this would negate cage adjustment. It was

decided that an attendant would ignore an animal in tantrum.

If the animal persisted and appeared to be exhausting 80 herself, the attendant should speak sharply, lift her quickly and put her firmly down in a prone position, rewrapping her in a blanket and walk away. During the fifteenth week an attendant was able to make this plan work as both animals came to the playpen bars and participated in a tantrum lasting one full minute. After being totally ignored, they became interested in each other, reached out, embraced and became quiet.

Another instance of human discipline seemed to have been effective during a feeding time when Mewar was in a play mood rather than one for feeding. She chewed on the edge of the jar, mulled the food in her mouth at length before swallowing it and was very slow in taking milk from her bottle. The attendant became irritated after Mewar became increasingly more squirmy and fidgety. She spoke sharply to Mewar and pulled her suddenly so that she was held very firmly. After that the orangutan paid more attention to the feeding session and began to take the food calmly and steadily.

Feeding Behavior

Melati and Mewar preferred to take their food directly from the jar after it was offered to them in that manner and after they developed the skills necessary to master "drinking." The infants either put an upper lip into the jar and scooped the contents out of the jar into the waiting oral cavity or formed the lower lip into a "chute" 81 into which an attendant would pour the food to be consumed.

This type of feeding was supplemented by using the tongue depressor for lumpy foods or those foods too thick to be poured. The twins were very good at rejecting food during the fourth month. They would purse their lips and refuse to open their mouths if a disliked food was offered. If a disliked food was taken, it was either pushed back out with the tongue or forcibly ejected with a coughing-like motion.

Gerbers Garden Vegetables (strained) was offered during many feeding periods before the infants would finally accept it. Gerbers Vegetables and Beef actually caused such indications of distaste as grimacing and gagging but after a few days was taken. Strained Beef was never accepted and the attendants stopped offering it after a few weeks. Since the pediatrician had recommended more protein, an additive of banana flakes, Probana, was put in their milk formula.

Although the twins were more alert and slept less than they did in the earlier months, they still seemed unadjusted to their feeding schedule.

A type of play behavior associated with feeding occurred with increasing frequency. The infants capitalized on the feeding period for non-nutritive oral satisfaction.

They enjoyed chewing on the nipple of the nursing bottle, mouthing the nipple and the food container and playing with the food by moving it about in the mouth before swallowing

it. The infants seemed to enjoy letting milk collect in a pool in the lower lip and then swallowing a large amount at 82 one time. If the infants were moderately hungry rather than very hungry, they took pauses in feeding to suck on an attendant's smock, a spare arm, a foot or to smear baby food over their abdomens.

Medical Information

After the addition of protein to the diet, the hematocrit rose to 43% for Mewar and 44% for Melati. It was discovered that the body temperature of the orangutans

fluctuated between 97.2**F and 100.2®F. A short study of

this was undertaken by the veterinarian and temperatures were recorded every 6 hours for one week. The conclusion was that thermo-regulation was not yet stabilized and variations in room temperature or whether or not the infants were covered with blankets was reflected in the body

temperature.

During the fourteenth week Mewar suffered from an

upper respiratory illness. It was suspected to be a cold

but since Probana had been added to the milk, the

possibility of an allergy was also considered. Her symptoms were those of nasal congestion, wet sneezes, chest wheezing

and occasional fever. At times her appetite was impaired

and she was lethargic. Other times she was irritable and

cranky. The illness lasted five days and was treated with a

decongestant, Corilan, a vaporizer, increased fluids and

additional clothing in the form of a Carter's baby shirt.

Probana was never reintroduced in her diet. 83

;|MifliiBtnTnnr— ,

Figure 6. Hanging from overhead bar with feet swinging free. 84

NURSERY — SEVENTEEN THROUGH TWENTY WEEKS

Development and Clinging Behavior

The fifth month saw a slow, steady increase in time spent using limbs and appendages. The development of locomotor skills ceased to be a traumatic and terrifying experience for the orangutans as they became familiar with new positions and combinations of new positions. Lying supine still caused periods of panic when the position was attained suddenly or unexpectedly. Although the infants had been observed to turn from a supine to a prone position, they seemed unable to use this skill as a problem solving technique. When lying supine, an orangutan would either scream until turned over by an attendant or until her sister would move over within range of vision to distract her. If an infant turned to the supine position

intentionally, however, she would lie quietly looking about at objects overhead or suck on her wrist or pacifier.

Grasping and clinging exercises seemed to be beneficial as more and more independent use of these skills became evident. The twins began reaching out to grasp bars as a means for pulling themselves into more desirable positions rather than grasping for experimental or

exploratory purposes. They learned to pull themselves into

a sitting position, then shift weight to the knees for a

kneeling position. The kneeling position then became a

standing position with more pulling and weight shifting. 85

The playpen floor was lowered another 4 3/4 inches to allow

the new standing position. Since the most active period in

the nursery was feeding time, each orangutan began to stand

at the rail of the playpen to watch her sister being fed.

During the nineteenth and twentieth weeks the beginning of

transfer clinging became evident.

The orangutans began experimenting with types of movement across the overhead bar and the upper playpen rail.

This involved grasping and clinging with both hands, then

reaching out with one hand to grasp another area while

supporting the weight with the remaining hand. After the

new cling area had been selected, a foot would reach out to

grasp a bar or rail for additional support while the

remaining hand was removed and moved over to make the

transfer complete.

As this period of development occurred during the

month of May, it was decided that the orangutans should be

taken outside for brief periods of time. The first three

times the orangutans were exposed to sunshine and grass they

appeared to be bewildered and uncomfortable and did not want to be placed on the grass or touch it. When the

attendant lay on the grass, the orangutans climbed on top

his chest and went to sleep. After this became a daily

program, the twins began to feel more at ease. They tasted

the grass and the soil and liked to find sticks to wave

about. On several occasions fresh branches of bamboo were

given to them while they were playing outside. Melati 86 experimented by chewing up a leaf and mouthing the branch but Mewar waved her branch and thrashed it everywhere, even while lying on her back. After two weeks we learned that the zoo-grown bamboo was contaminated from traffic pollution and unsafe for the twins to handle, even after a thorough washing. Bamboo was withdrawn from zoo animals as a dietary option while a search was made in suburban areas for a

lead-free source. Those animals requiring bamboo were fed washed bamboo and the small amounts of bamboo grown in the yards of private citizens in less polluted areas.

While outside, the orangutans were too insecure to

travel far from the attendant. They would venture out a

few feet away and examine what they saw underfoot, then come

back to make contact. These periods usually ended with the

orangutans lying on their backs next to the attendant,

sunning their stomachs and falling asleep. When they were

carried about outside, an attendant would put an orangutan

under each arm, allowing the orangutans to cling tightly

enough to support their weight. They preferred to grasp and

cling to hair (Figures 7 and 8) and were difficult to

untangle after the trip was over.

Tantrums became more and more frequent and there

seemed no successful way to handle them. They began to

occur daily at feeding times and hunger seemed to play a

minimum role in the cause of the tantrum. We surmised that

lack of attention was the reason for the ceaseless

screaming. The twin left behind in the playpen would sit. 87

Figure 7. Orangutan clinging to hair. 88

W.V,

Figure 8. Orangutan clutching hair and finger, 89 kneel or stand at the rail, screaming and thrashing continuously until picked up. If she had just been fed and her sister was being fed, she would still scream. Mewar began rocking back and forth on all fours hitting her head against the bars until her head was covered with small lacerations. Twice an attendant was able to stop the tantrum by singing during the feeding time but once the novelty wore off, the tantrums were resumed. At this time the twins began reaching their arms out if it appeared that a passing attendant might pick them up.

There was also an increase in aggressive contact behavior. Some days it would not occur at all and other days it would occur so many times in a row that an attendant would be busy continually separating the twins. This activity appeared to be purposeful, with one animal always reaching out and persistently pulling her sister until she was turned over or lost her balance and fell. The aggressor would then lunge on top and suck. During this month teeth erupted, making the activity one of great discomfort for the victim. The infants were covered with bruises and suction discolorations as well as bleeding lacerations and tooth marks. A chart was kept to determine which animal appeared to be dominant but at the end of each week, both animals had taken approximately the same number of turns pinning each other down. The position assumed was always ventro-ventral.

Sometimes the animal on the bottom would lie still for awhile and remain quiet but eventually would tire and begin 90 to shriek until rescued. These sessions were never spontaneously resolved but always required interference before an animal became severely injured.

Medical Information

Although the infants seemed to be increasing in weight and physical development as well as developing new skills, they spent periods of time without much appetite and appeared to be lethargic. One attendant noted that the twins smelled foul to him during diaper changes and the feces had taken on a different scent. After a culture was taken, it was discovered that the twins were harboring

Staphylococcus in the intestinal tract. Nose, throat and blood cultures were all negative for this organism.

Tetracycline, a broad-spectrum antibiotic, was ordered to be administered at each feeding time. The infants had a very difficult time taking this as they apparently found it distasteful and always gagged and choked while attempting to swallow it. Tetracycline is rarely administered to human infants because it leaves permanent deposits in newly forming teeth causing the teeth to bear a life-long stain.

There are other antibiotics as effective as Tetracycline which can be used in most cases but most people would not consider attractive teeth an asset to an orangutan's appearance. In some instances. Tetracycline, Ampicillin and

some other antibiotics destroy the normal intestinal flora, particularly in infants whose digestive tracts are unstable. 91 causing diarrhea throughout the course of the medication.

A pediatrician will usually take such an infant off all antibiotics, stabilize the diarrhea through a progressive liquid and bland diet such as clear fluids, jello and rice cereal and then attempt to reintroduce the intestinal flora through cultured foods such as yogurt and cottage cheese.

An alternate antibiotic is administered in an attempt to avert the former gastro-intestinal upset. As soon as the orangutan twins started taking Tetracycline, they developed severe diarrhea with excoriation and skin breakdown in the genital and anal regions. For the first time the infants indicated signs of diaper discomfort and would refuse to eat until their diapers were changed. The veterinarian attempted to regulate the bowel problem by stopping the

Tetracycline until the stools seemed to be approaching normal consistency and color and then leave an order to restart the medication. Whenever the Tetracycline was restarted, it always triggered another bout of diarrhea and gastro-intestinal discomfort. Finally, even though the medication was permanently withdrawn and the Staph controlled, the intestines were so sensitive that the diarrhea persisted for over a month, unresponsive to anti- spasmodics and bowel depressants. Severe skin breakdown was made worse by increased heat and moisture from continuous plastic coated diapers. Vaseline was abandoned in favor of

Desitin Anti Bacterial Powder, then Almicorten V, a steroid

creme, was added to the diaper changing routine but healing 92 was very slow. Mewar developed a cystic blister in her

perineal area which grew large and eventually ruptured.

Melati's excoriated skin managed to clear with the creams,

careful washing and frequent diaper changes but Mewar did

not heal until she was allowed to go without diapers for

prolonged periods of time. After approximately two weeks of

air exposure the swelling and redness subsided and there

were no broken areas visible in the diaper region.

One particular incident happened that was of

interest but perhaps of no value. The veterinarian made an

attempt to draw blood from Mewar's jugular vein but could

not get her to be still. He tried to place the animal in

two different positions but was unable to reach the vein

easily. At first Mewar was calm as she lay on her back in

the veterinarian's lap with her head extended backwards,

then she became uneasy and emitted chirpy cries of

discomfort. The veterinarian became exasperated and sat her

up in his lap. He then playfully slammed his fist toward

the side of her face as though he intended to punch her.

Mewar immediately collapsed in a forward position and became

limp. She let go with hands and feet, her eyes became dull

and a large foam of saliva drooled from her mouth. It was

approximately one minute before she made another normal

movement. At this point, the veterinarian drew blood from

the back of her right lower leg. She remained lifeless and

did not react in any manner during the venipuncture but

appeared normal when placed back in her playpen. We did not 93 know whether this reaction was one of fright, startle or shock. We felt she must have been experiencing some sort of shock reaction as her behavior was totally different from the behavior of Melati during the actual venipuncture.

Melati squirmed and chirped during the entire procedure with many expression changes, particularly when the needle was being withdrawn.

Consultation on Development

Barbara Harrisson, a pioneer in orangutan studies and founder of the orangutan rehabilitation programs in

Borneo, visited the National Zoological Park and observed the infants in the nursery. A meeting was held for the directors of zoo programs, the research staff and those actively responsible for the health and welfare of primates.

At this meeting. Dr. Harrisson had many comments and suggestions regarding the management of the orangutan twins.

The nursery staff was advised that during the first year it is important for infant orangutans to have some type of mother substitute. Orangutans are in constant contact with their mothers for the first nine months of life. After

the nine month period, they begin an exploratory period

using the mother-infant bond as the focus point of return.

An infant orangutan reared without a mother or a mother

substitute is much slower in developing because it does not

have the necessary stimulation. Dr. Harrisson felt that the

goals set by the nursery staff to avoid human imprinting 94 were realistic goals and could be met if the staff could make the infants feel secure. The rotation of staff members should also provide for a transition of security from shift

to shift as well as providing adequate stimulation. In her studies of orangutans. Dr. Harrisson had never been in contact with newborn orangutans but had received orangutans whose ages corresponded with the age of the twins. It was her conclusion that a young orangutan needs stimulation 30% of the time and some of that stimulation must come from a mother or mother substitute. An undesirable effect of early

and prolonged peer dependency without maternal guidance is

the tendency toward prolonged clinging. Two orangutans

received in Dr. Harrisson's reserve had been reared together without much stimulation from any area. Although the

youngsters were ages two and three, they resembled Siamese

twins. Their grasping and clinging problem was so severe

that most of the time climbing and walking was impeded by

the need to clutch a partner,

A year after that meeting, results of a study were

published by Chamove, Rosenblum and Harlow (1973) confirming

Barbara Harrisson's observations of orangutans raised only

with peers. This publication stated that rhesus monkeys

raised only with peers engaged in increased ventro-ventral

clinging during the first months of life and later engaged

in dorso-ventral clinging for considerable amounts of time.

Harlow (1969) had already published some studies on age-mate 95 socialization but no one was familiar with the study at the time the twins began to exhibit this manner of clinging.

Everyone was vitally interested in making the introduction into the zoo environment a success for the orangutans. Dr. Harrisson was asked for recommendations on handling the introduction. She felt the twins should be at least nine months old or older before their break with the nursery environment as that period of time would correspond with their natural age of exploration. A cage should contain moving objects rather than static equipment for stimulation. Chains encased in plastic or very large swinging ropes are ideal for the type of grasping and locomotion an orangutan needs. She particularly warned against small ropes that could be easily manipulated. In her experience, she had known apes to hang themselves during play with ropes that became easily knotted and tangled.

The person who would be in charge of the caged infants, the head keeper of The Small Mammal and Great Ape

House, was present at the meeting and heard all the suggestions for the rearing of the orangutans during their introduction to the cage. His attitude was not one of openness and he seemed to assume that the meeting was an attempt to undermine his authority by telling him how to raise his animals. He felt proud of the fact that he had never read a book on apes but had managed to raise several

apes in captivity, that he could face them without fear,

that the public seemed to like his apes and that they seemed 96 healthy enough to him without all the bother over psychological adjustment. His main concern was that programs were going to be suggested that would deplete his manpower and he did not feel that the apes deserved any more time than the other animals under his care. Another of his concerns was the possibility that the suggested play equipment and developmental materials would require special cleaning and create a heavier work load. For instance, straw was suggested as nest building material for the orangutan cages but instantly condemned as it would need to be changed daily when the cages were hosed, taking more time than usual. When such issues as weaning age were brought up, the Head Keeper was not interested in results of weaning studies because the public enjoys watching animals with nursing bottles. A bottle prolongs an animal's appealing cute period and it is less work to give an animal a bottle than to initiate weaning and teach the animal to drink milk from a cup. As examples, the Head Keeper told of two of his previous orangutans shipped to another zoo at the ages of

1 1/2 and 2 years of age. Both animals were bottle dependent on departure and threw tantrums when the bottles were removed for any reason. The zoos receiving the animals were dismayed over having such "spoiled" and "infantile" animals thrust upon them as these animals were to be

incorporated into breeding programs. However, as far as the

Head Ape Keeper was concerned, these babyish animals had

drawn large crowds and were much more appealing to the 97 public than they would have been without the bottle and accompanying tantrums.

The interesting possibility of maternal réintroduction was discussed which also met with opposition from the Great Ape Keeper. Since Jennie, the orangutan mother, was a gentle and reasonble animal all kinds of réintroduction ideas might have become reality. One popular suggestion was to leave the infants with their mother but make provisions for feeding and escape by building a play area adjacent to the large orangutan cage. The infants could retreat into their own play area as long as they were small enough to squeeze between the bars. This type of plan would enable them to get out of the cage during their feeding times and choose how much mother-infant contact would take place. Although this seemed like an experiment worth trying, the Head Keeper felt that the ape area was simply too crowded to plan adjacent quarters for the twins and that the installation of a play area would cut down on available working space for zoo personnel.

NURSERY — TWENTY-ONE THROUGH TWENTY-POUR WEEKS

General Development

During the fifth month another developmental plateau was observed. The orangutan twins spent most of their time practicing the skills they had accumulated during the first

four months and improving in the areas of self confidence 98 and coordination. There were few motions that could be called new and opportunities were not given them to improve in new areas of development or increased independence.

There was better coordination of hands and eyes.

The infants could reach out for objects and grasp them but could not bring the objects to their mouths. Instead, they reached out with their mouths to make contact with food or interesting objects. Both Melati and Mewar were able to hold their bottles without assistance whenever given the chance. Prolonged tantrums became more and more frequent from each orangutan as the other one was fed. As the infants became stronger they would attempt to climb up the vertical crib bars to reach the busy attendant and interrupt the feeding period. If the attendant was feeding an orangutan within reach of the playpen, the remaining orangutan would clutch the attendant or orangutan through the bars and pull insistently while screaming. Some of these tantrums lasted as long as ten minutes with an animal rocking back and forth on elbows and knees, striking the head repeatedly against the bars and screaming. Sometimes an orangutan would become so excited that the tantrum would continue for several minutes after being picked up and carried by the attendant. No solutions were reached on how to stop the tantrum but, on the other hand, no effort was made to reduce the competition between the two at feeding time. The twins were capable of holding their own bottles if the bottles were not too full but were never given a 99 chance to feed themselves in the playpen. They were introduced to fruit cocktail and liked it but were never left alone with a quantity to handle, manipulate and eat unaided. They were still totally dependent on humans at every mealtime. The only times the infants were offered water was when they appeared to be overeating. They were never offered a bottle of water to drink at whim in the playpen nor were they taught to drink water from a spout or licker as they would be forced to do in the cage.

Social Development

More social interaction came about between the attendants and the orangutans during the fifth month. This social play was stimulated by the orangutans who seemed to need to play with the attendants during feeding time. The orangutans began to mouth the faces of the attendants, if permitted, in a gesture resembling a kiss (Figures 9, 10, 11 and 12). Quite often an infant would become distracted at feeding time by the food container, buttons on clothing or the food itself and want to touch and feel the object of interest. This usually stimulated the attendant into talking

to the orangutan and even scolding the orangutan for losing

interest in the meal. The orangutan would, in turn, mimic the facial expression of the attendant. The attendant would

then respond by either playing with the orangutan or becoming more serious. Either way, a chain reaction would 100

u O > ta

S' •H to to •H

XSc nJ atn •Hu 0) Ü 3 A a\ u0) tr> •H 101

m m

Figure 10. Response to attention at feeding time. 102

Figure 11. Puckering and kissing behavior. 103

c o •H +J u •HQJ m •oa ta g’ •H tn 3CP b O -P OJ (0 c o tna o P.

«-H 0) P •H 104 come about which always meant the orangutan would receive some sort of attention at feeding time (Figure 13),

By now the mutual aggressive sucking behavior had become a pronounced problem. Restrictive actions directed toward each other began to occur regularly and frequently.

The infants took turns several times a day pinning each other down and sucking on each other. If one infant was chosen to be fed first, the other infant would grab her and hold her until the attendant disengaged the two. Whenever an orangutan attempted to travel or explore, she was usually held back by her sister and was unable to free herself without assistance. A playing orangutan was nearly always interrupted by the orangutan without interest in toys or exercise and physically halted. This action did not appear to be playful or friendly as the aggressor used whatever means necessary to stop her sister from continuing normal activities. These methods included biting, hair pulling, squeezing and bodily pinning an animal down by lying on top.

When the infants were outside and attempting to crawl or travel on their own, whichever twin was faster (usually

Mewar) would be physically stopped or impeded by her grasping sister who would often attempt to climb on top and ride piggy-back. Twice, when the twins were outside, Mewar turned her aggression on the attendant, lunging at him and biting him repeatedly. The first time this happened, the attendant was very surprised and attempted to suppress the attack by holding Mewar off with his hands. The second time 105

Figure 13. Mimic expressions, 106

Figure 14. Reactions at play time. 107

4-)

>; fd f—( a +j (d (fl c o •H +J O fd

tn

U0) & -H 108

Mewar made such an attack the attendant became annoyed and' returned the bite. The retaliation was apparently effective as Mewar gasped and backed off, then returned to lunge again but not as confidently as before and void of biting behavior.

In Chapter 5 the results of the studies of Harry and

Margaret Harlow, A.S. Chamove, Yyvette Spencer-Booth, R.A.

Hinde and others are recounted. These studies of isolated and maternally deprived rhesus monkeys have revealed some behavior patterns very much like some of the disturbing behavior exhibited by the twin orangutans. Behavioral scientists had found that it was not enough for an infant monkey to be fed and kept warm but that other needs had to be met for the animal to react normally as it grew and developed. Besides the needs for stimulation and exercise along with the teaching a mother imparts to her offspring, there is also a need for rejection and punishment at the appropriate times. It appeared that Melati and Mewar might have been ready for rejection and punishment, particularly during attacks on attendants. However, at this time and later on, most of the attacks and biting were allowed to go unchecked. This was because some of the attendants viewed punishment behavior as a human to orangutan reaction rather than an animal to animal reaction. They felt that their form of punishment would reflect the values a human

(particularly a Western human) places on the behavior of a child and that an orangutan should not be reared to behave 109 in the manner a human child is expected to behave. The attendants could not have been expected to respond in a different manner as all were hired for the sole purpose of caring for and cleaning up after the animals owned by the

National Zoological Park. They were not specialized to care for any particular breed of animal and were not required to do any preparatory reading or research to function satisfactorily in their jobs. None of them could have been expected to be aware of previous primate behavior studies and some of the studies that would have been particularly helpful were published after the nursery rearing period had ended. One very obvious aspect of allowing human-directed aggressive behavior to continue was not even considered and that was the concern for the future safety of attendants and keepers who would be handling Melati and Mewar as adult caged orangutans. The infants were establishing behavior patterns they would probably carry with them into adulthood.

Although they were still young and small enough for human physical control, before the end of the year they could become physically dominant and perhaps dangerous if allowed to continue their aggressive behavior unchecked.

Progress Toward Cage Adjustment

During the twentieth week the infants were placed on the floor of the nursery. This surface was smooth cement covered with paint. It was cold, solid and quite like the surface the twins might expect in the cage. Neither could 110 deal with the new surface and spent the entire period cuddling blankets and crying. After two more tries the experiment was abandoned. At this particular stage, the

infants were not progressing much during play periods. They

spent a lot of time mouthing the equipment in their playpen, hanging from the overhead bars and attacking each other. A

great deal of time was also spent throwing tantrums. The

time seemed ideal to divert the infants into more

stimulating and attention diverting activities. More time was spent in taking the orangutans outside to play on the

lawn. Again, very little imagination or planning was used

in organizing the outings. The attendants usually sat on

the grass and watched the orangutans do whatever they felt

like doing. No guidance was offered in an effort to channel

activities into good developmental experiences. The twins

experimented with the tastes and textures they found outside

but were too insecure and underdeveloped to attempt any type

of exercise or travel. The sessions usually ended very

shortly with the twins climbing atop the attendant and

falling asleep or lying on their backs, sunning their

stomachs and falling asleep.

Both the indoor and outdoor play periods might have

been converted into experience building programs with some

forethought, planning and keeping the goals of cage

introduction in mind. The National Zoological Park had many

tall cages on hand in the hospital section of the Research

Building. These cages were large enough to comfortably Ill house primates as large as the adult lion tailed macaque and would have made adequate play areas as well as helping provide introductory cage experience for the twin orangutans.

Since the twins needed more exposure to the floor surface and had never experienced metal bars, one of these cages

(or two with independent development in mind) could have been placed in the nursery for play periods. The addition of appropriate play and exercise equipment to the cages might have made the occasion stimulating enough for the

infants to decrease the time spent in sucking each other and

throwing tantrums. The same setting could have been

duplicated in the outside environment by hanging some ropes

from the trees and providing stimulating exercise opportunities. The orangutans had demonstrated limited

crawling ability but were cramped for space in their playpen

and had been unable to travel very far. In an outside

setting, their locomotion could have been encouraged by making them travel short distances on their own instead of

being carried everywhere. Introduction to strangers might

also have been helpful at this time as the infants tended

to stop all activities and stare whenever an unfamiliar

person entered the nursery. During feeding periods nothing

could be accomplished in the presence of a stranger because

the twins became absorbed in the new experience of having a

visitor. A segment of the time spent outside might have

included trips to the public zoo areas to acquaint the twins

with the sights, sounds and smells of the visiting public as 112 well as trips to the large orangutan cage to give Melati and

Mewar a good look at their parents. One of the feeding periods might have included some unfamiliar observers or the twins might have spent brief periods of time in a cage simply observing the public.

NURSERY — TWENTY-FIVE THROUGH TWENTY-EIGHT WEEKS

General Development

Only two significant locomotory developments were observed during this last month in the nursery. A hand over hand clinging and grasping pattern became useful for movement along horizontal bars and climbing up vertical bars. The second development was the beginning of a quadrupedal walk which was exhibited only when the twins were outside. Since there was no room in the playpen for this type of locomotion and the orangutans were never placed on the nursery floor to practice moving about, walking experiments were rarely observed. A long rope was hung from the nursery ceiling down into the playpen in hopes that the twins would learn to climb it. However, the area was too crowded and the orangutans could not take hold without swinging into the sides of the playpen. After several such crashes, the rope was removed. Again, had the infants been allowed to approach the rope from the floor area, there would have been no obstacles for them to encounter in their swinging and climbing. By this time the infants had become 113 very confident on their familiar play equipment. Mewar began to hang upside down on the horizontal bar using both hands and feet. Both orangutans began to climb up the vertical bars of the playpen in an attempt to reach the attendant's lap. Although both were capable at this time, neither seemed to consider climbing over the top of the playpen and down the other side to reach the attendant.

Instead, the orangutans would climb up to the top of the playpen using hands and feet, hang on with their feet, turn

loose with their hands and lean precariously out into space, gradually losing their balance and screaming until rescued.

If a mat or soft covering (sawdust or kapok) had been placed

under the playpen to absorb the shock of the fall, the twins might have learned from experience not to hang over the top

edge of the playpen and to climb over instead. As

circumstances were, the attendants were too fearful to allow

the orangutans to fall on the concrete floor and dashed to

the rescue every time, often catching them in mid-air as

they fell.

A tall sawhorse was constructed for play purposes.

At the time the twins went into the cage, they had not

learned to play on it with confidence. On occasion, with a

little coaxing, the orangutans would climb up one side,

slowly swing hand over hand to the opposite side and climb

down. Usually, they climbed up one end and back down again.

Another pattern observed was to climb up one end, swing out

to the middle of the horizontal bar and panic. This would 114 result in the animal hanging only a few inches above the ground and screaming, afraid to let go and afraid to go further. If the orangutan continued to hang and scream for a long period of time, she would be rescued as the attendants thought it unwise to let an animal tire in this manner. This particular action reminded all concerned of the classic example of young kittens stuck in the top of trees, afraid to come down. Usually the orangutans were allowed to work out the problems for themselves. With much whimpering, an orangutan would either turn around and travel back to the side she started from or continue to progress along the bar to the other side, making each movement with hesitation, reluctance and apprehension. At this age, hand-reared infant gorillas are very confident in climbing above the ground and returning again. One observed pattern

is that of letting go with hands and feet and dropping the remaining distance in a free fall. The orangutans were never that confident during their entire nursery period or during the caged period under observations.

Social Development

The problem of the tantrums was carried over until

the 27th week. Tantrums became longer, louder and stronger with the addition of more behavioral elements. Before the

seventh month the orangutans were screaming and beating

their heads against the playpen rails. Now they began to

tear the sheets and bedding with their teeth while screaming 115 as well as flailing arms and legs about and striking their heads and bodies against the rails. Tantrums could last as long as 25 or 30 minutes. At this time, when one infant was being fed and the other infant was having a tantrum, the

infant in tantrum would often attempt to climb out of the playpen onto the attendant's lap to share the feeding with her sister. Some attempts were made to feed the infants

together at the same time in the attendant's lap. This was very difficult and successful only with one attendant and only two or three times out of many attempts. The main problem was that each infant wanted whatever the other

infant was eating or drinking at that very moment. This resulted in the orangutans grabbing each other's bottles back and forth and reaching out for a tongue blade loaded with baby food before it had time to reach an open mouth.

The aggressive-sucking behavior continued as before with one new variation. The infants now began to bite each other during playful wrestle periods as well as during the other type of contact. More instances were recorded of an orangutan persistently biting an attendant in spite of a

light slap across the face or stern admonishment. According

to the record, the frequency and duration of the attacks

appeared to diminish during the seventh month prior to

entering the cage. 116

Cage Preparation

The twins had not been made responsible for their own feedings. Due to the pattern built up, they still depended on being fed by a human and expected a human to hold their bottle and whatever piece of food they were expected to eat. Bottles left in the crib met with little interest as the orangutans simply did not feel the need to drink from them although they were capable of holding their own bottles. Since the orangutans were still on a feeding schedule, regardless of their performance of sucking on a bottle in the crib, they were picked up to be fed at the appropriate time whether hungry or not. With introduction into the cage only two or three weeks away, small food piles were left in the cage for the twins to snack on. These piles consisted of fruit cocktail, banana, cheese and meat sticks. Most of the time, the twins were not hungry enough to eat these and merely played with them and mashed them into the playpen surface. No competition was shown in the playpen area over the food probably because the orangutans were not interested in it.

Plans had been made to introduce the twins to the cage when they reached the age of six months. When that time came, they were still very dependent on the attendants and the cage was still not ready. Quite a period of time was spent waiting for the protective glass to arrive, painting the cage, and installing the play equipment. 117

Figure 16. Orangutan attempting to hold bottle, 118

I will briefly outline a letter Barbara Harrisson wrote to an employee at the Research Building regarding cage introduction. This letter was received when the twins were six months old and initial cage plans were being made.

Dr. Harrisson felt it was important to introduce the infants to the cage at approximately nine months of age and make every effort to incorporate stimulation for development and integration into existing structures at the zoo. For moving about in the cage environment there should be flexible, moving structures providing incentive to climb up.

These should include attractive resting features above floor level to discourage resting at the floor level. Permanent features are needed which allow the animals to hang and brachiate extensively at the ceiling level and to move within provided space so that all features could be visited without an animal ever coming down to ground level.

Conversion of existing structures should be provided for introduction of increasing variety through the gradual extension of a. space, b. occupation and c. contacts.

a. Space: Increasing use of given space through introduction of equipment and through introduction of variety of spaces occupied in routine life.

b. Occupation: Increase use of time by spaced feeding and the introduction of a variety of foods. Maximum trouble should be taken to introduce spot feeding, possibly connected with climbing structures. Avoid feeding orangutans at the ground level. Introduce nesting material considering 119 the possibility of other materials substituting for branches and leaves. Introduce varieties of materials that may be manipulated. Make the observation of visitors interesting to the orangutan by manipulating the visitors' potential.

c. Contact: Depending on existing dependency on human contact, provide gradual réintroduction to the natural orangutan mother. In view of the fact that both the infants

are female and the present adult female is apparently

friendly, a stable compatible female unit could coexist in a

large cage unit beyond adolescence and allow for gradual

accommodation of the natural raising of future infants in

this environment, A controlled vicinity of subadult and

adult male can be maintained since the zoo possesses one of

each at this time. These types of contacts make a promising

beginning for the development of a natural orangutan

breeding colony.

CAGE — TWENTY-EIGHT THROUGH THIRTY-TWO WEEKS

At seven months of age or twenty-eight weeks, the

orangutans were taken to their new cage and left there without any prior introductory period. For the two weeks

before cage introduction the attendants had been turning out

the lights for part of the night and leaving them alone for

a few hours. For six and one-half months the orangutans had

not known night or lack of company because the nursery lights

were on continuously and an attendant was on duty for 120 twenty-four hours. There were no windows in the nursery so it was impossible to tell the difference between day and night. At the time the twins went into the cage, they had never slept on a floor and had never been without the comfort of the soft, padded playpen and someone to cover them with blankets when the temperature was low.

The suggestions made by Barbara Harrisson for cage design were not considered. There were no resting platforms above the ground and all the play equipment was stationary.

No provisions were made that would allow the twins to live at ceiling level or to feed in that area. No nesting material was provided. The twins were allowed to keep their blankets but there was nothing else for them to manipulate or experiment with.

Food was left in the cage for the twins at 4:30 p.m. and when the keepers returned at 7:00 a.m., the food was gone. The natural assumption was that the twins were eating it. Every morning the orangutans were fatigued, lethargic, sleepy and absolutely ravenous. After they gorged on their morning food they fell into a sleep so deep that the cage could be cleaned around them and they would not waken. During the times they were outside they seemed too tired to exercise and attempted to continue their sleep.

When they were awake, they spent the time clinging to each

other and cuddling their blankets.

The camera installed above the cage could not take

clear pictures at night with the available light and was too 121 far away to pick up small details. However, the white blankets photographed well in the semi-darkness. The time lapse pictures revealed the blankets being moved about all night which indicated that the orangutans were restless and not sleeping soundly as they had during their nursery experience. One morning Mewar's right ear was bloody and appeared as though it had been chewed. The Head Keeper blamed it on Melati and said it was dangerous to leave the two orangutans together at night as they were spending the night chewing each other.

The situation of sleeplessness was made clear when a worker passed the cage one night to look after an animal in labor. The cage housing the twins was full of rats and mice. The rodents were eating the food left for the twins and actually sitting atop the orangutans as they attempted to sleep. The worker removed the food and chased the rats away but found them back again when he passed through later on.

The keepers stopped leaving food in the cage overnight and left mouse traps around the outside of the cage. No mice were ever caught, Mewar's ear remained bloody and raw and the infants were still not sleeping at night.

During the thirty-second week, the Head Keeper stated that the twins were psychologically bad for each other. He placed minimum importance on rodent disturbances and major importance on the clinging behavior exhibited by the twins toward each other, calling such actions "perverted" 122 and unnatural. In order to give the twins a "rest from each other" and make them settle down into "normal" cage life, a partition was constructed across the cag^ to separate the two. This partition was approximately six feet tall and had a plexiglass window at the bottom enabling the twins to see and hear each other but not touch each other.

Even though the carpenters were actively building in the cage, no attempt was made to construct sleep areas above the floor to remove the orangutans from the pathway of the rats.

This same week an unplanned attempt was made to introduce the twins to their mother. In actuality, the twins were carried to their mother's cage and placed in it.

The results were that the infants remained lying on the floor of the cage, clinging to each other in fright without making a movement or a sound and the mother orangutan remained in her area of the cage simply staring at the twins. After a few minutes, the twins were removed and the reintroductory attempts were abandoned for several weeks.

CAGE — THIRTY-THREE THROUGH THIRTY-SIX WEEKS

When the twins became separated they began to exhibit frenzied and unstable behavior from the first day of separation. Tantrums occurred every time a worker entered the work space behind the cage. Whichever animal was on the side with the door would climb up the bars and scream the entire time the worker could be observed in the vicinity. 123

The orangutan on the other side of the partition, having no view of the work area, would huddle on all fours over her blanket and whimper. Both infants became afflicted with diarrhea the very day the partition was built and continued to have diarrhea for the three months that followed. The attendants could not get the infants to eat as they had before. At feeding time, each infant would greet the attendant with frantic grasping, clutching and body contact.

The twins could not be pried off easily and would not relax enough to eat in the manner they had been accustomed to eating. When it was time to put the infant into the cage

again, the orangutan would struggle and tighten her hold. I

found it nearly impossible to take measurements at this time

as it was extremely difficult to disengage a screaming,

grasping animal, determined to cling with both hands and

feet. The first night the infants were separated, Melati managed to climb over the wall to be with her sister. This

action was rarely repeated because the twins were not strong

enough and lacked the climbing experience necessary for the

success of the feat. There also seemed to be more to the

problem than lack of climbing skills. This aspect may have

been caused by lack of experience and that is lack of

innovative behavior or lack of rapid increase in learning

skills. From birth, the orangutans were not overly curious

or experimental with what environment they had to work with.

They did not seem to catch on to new routines quickly and

were not good at manipulating new objects introduced to 124

them. It could be that they were never given materials that would stimulate them into building up new and helpful

experiences. This same situation was duplicated in the

cage. The orangutans played, but did nothing new with their

play equipment, spent a great deal of time lying about on

the floor clutching their blankets and never looked at each

other through the plexiglass window in the partition. In

Chapter 5 results of studies by Rumbaugh, Davenport and

Rogers and others interested in learning behavior of apes

will be summarized. Some of these studies have demonstrated

that captive apes restricted from an early age are less

task-oriented than wild-born apes, that orangutans are more

difficult to motivate than chimpanzees and that restricted

apes lack the ability to apply their skills to new

situations.

From the day the partition was built in the cage,

Melati and Mewar began to decline in health. The diarrhea

that had been so difficult to clear in the nursery returned

in its same persistent form and lasted for months. The last

observational notes kept on the twins in November at the

time they went into the large cage near their mother

indicated that diarrhea was still a problem. Aside from the

diarrhea, separation and the rats at night, other factors

made the twins inhappy and irritable. Melati and Mewar had

lived in the nursery with controlled temperature for seven

months. They were introduced to the cage in the middle of

July. The Small Mammal House has no air conditioning and 125 becomes stuffy and hot in the summer. All ventilation comes from fans and the open door. Animals fortunate enough to have access to a cage outside the building are able to find some relief, even though it is also hot and humid outside.

Melati and Mewar perspired profusely in their cage. Fans were installed above the cage when the twins became feverish and began to register internal temperatures of 100“F. This was also an active teething period with the eruption of the premolars occurring in both orangutans. All solid food had been withdrawn from the twins because of the diarrhea, leaving them with nothing to chew during this teething period. After nights in the cage with no food and no solid

food during the day, the keepers began to notice that in the morning the infants had stained teeth from eating fecal material and appeared to be very hungry. During the thirty-fourth week the keepers began to leave monkey chow in the cage because it was obvious that Melati and Mewar could not cope without night feedings or solid food.

During this period of agitation, irritability and

illness the veterinarian took blood samples for various

tests and had the twins X-rayed. The results of one of the blood tests indicated an elevated serum bilirubin. This pigment in the blood serum shows the functional capacity of

the liver in breaking down, re-using and excreting bile

pigments (Widman 1973:130-133; Beeson and McDermott 19 67:

971-973). An elevated bilirubin is a sympton of liver

disorders or malfunction. The main problem with this type 126 of test and other blood and urine tests performed on samples from the orangutan twins is that the veterinarian had no normal orangutan values for comparison. All tests performed were measured by human values. An elevated bilirubin by human standards may have been normal for an orangutan. Other institutions conducting medical research programs on apes and even some zoos (Buchenholz 1974:40;

Conant 19 64:93) would have access to this type of information from running series of blood tests, urine and stool tests and X-rays on apes as part of a routine PE.

The National Zoological Park does not have this type of information for its apes, as it is not involved in routine health care. No tests are done on apes unless it is suspected that they are ill. When an animal is first acquired by the zoo, no preliminary bloodwork or detailed examination is done to evaluate the animal's health status.

When an animal dies, an autopsy may or may not be performed and there is no storage of information which might be of aid in related circumstances. Autopsies are usually done by students who are not expert enough to recognize unusual abnormalities. When an autopsy is performed on a rare animal, even a seasoned veterinarian may not recognize the normal boundaries of the internal organs if he has never performed surgery on that type of animal.

When the attendants observed the course the cage introduction was taking, they decided to make an effort to introduce the twins to their mother as soon as a plan could 127 be agreed upon. This introductory period was not carried out for several weeks and for many reasons. The first problem was how to feed the infants in the presence of their mother. As mentioned before, the Head Keeper was not willing to set an area aside for the twins use during feeding and play periods. It was feared that the mother orangutan would carry the infants about and hinder their intake by never bringing them near the keepers and never sharing her food with them. Another problem was the nature of the mother orangutan. Jennie was a very gentle and reasonable animal but retarded in maturity because of encagement. She had come to the zoo as a young wild-born animal and had learned to spend her time in the cage as a lethargic, unstimulated and unmotivated animal, dependent on humans for her every need. Although she might bring the twins to the keepers during feeding times, past experiences with her other infants had shown that Jennie wanted the nursing bottles and baby food herself and would take whatever was offered away from her offspring and consume it herself.

During the thirty-third week a urine test confirmed another pregnancy for Jennie. This complicated plans for cage introduction of Jennie and her twins. Since Melati and

Mewar were unwell, it was feared they might transmit some sort of contagious illness to Jennie or her unborn infant.

The possibility of the uncomplicated birth of a rare, expensive animal took precedence over the final stages of 128 mother-infant réintroduction and so the program was postponed until the twins began to appear healthy again.

CAGE — THIRTY-SEVEN THROUGH FORTY-SIX WEEKS

The last portion of habitation in the Small Mammals

House was not overly eventful. The attendants continued to keep the twins separated. They were taken outside on the grass for some fresh air and exercise daily while the cage was cleaned. If enough help was available, they were taken separately by different attendants. When one attendant took the two outside together, efforts were made not to let the two come into contact with each other. When tested for abilities in locomotion and climbing, Mewar was still much stronger and faster than Melati, as she had been during the nursery period. Contrast films revealed Melati as deficient in coordination and strength. When placed on the lawn and forced to ambulate 25 feet to reach the attendant, Melati seemed to find it an overwhelming task. She was not as fast as Mewar and seemed to tire after approximately 8 feet, becoming very slow by the time she finally reached the attendant. She always favored her left side which seemed to lack the strength of her right side. Overall, Melati's ambulation pattern was one of attempted quadrupedal placement but failed somewhat in that she seemed to drag her limbs, particularly the left ones, shortly after she began.

She also seemed insecure and lacked confidence, crying and whimpering until she finally reached the attendant. Mewar, 129 on the other hand, had no problem ambulating the entire 25 feet at a brisk pace. On film, if one forgets the grass belongs to the zoo, it is easy to imagine Mewar as a wild-born orangutan in her natural habitat. She moves in a true, coordinated quadrupedal gait, using her knuckles and never faltering until she reaches the attendant. Her movements are rapid and smooth and her long hair flows and catches on the grass as she moves, capturing true orangutan locomotion appearance. Mewar appears confident on film.

During the times she was tested and filmed, she did not accompany her movement with whimpering or any noise at all.

Contrast films of locomotion taken throughout the summer always reveal Melati as faltering, insecure and less coordinated. When her films are viewed alone and in sequence, progress and development are apparent. Her

locomotion does improve in strength, purpose and efficiency and it does not appear that she is a defective animal.

Apparently both orangutans were in different stages of development most of the time.

Around the thirty-eighth week the twins appeared to be resigned to their plight in the cage. They may have been

so fatigued by their persistent illness, lack of sleep and general discomfort from the heat that they found the

screaming and outbursts required too much energy. Time-

lapse film revealed the orangutans were not moving about as

much at night. Either the rat problem was controlled or the

twins began to sleep in spite of it. The film also revealed 130

the animals awake and moving about for the day around 3:30-

4:00 a.m., long before they could have their first meal of

the day. The diarrhea was treated with a variety of medications but was never completely controlled. At times

an infant would go for two days with no bowel movements and

then have diarrhea for the following week. No blood studies were done to determine electrolyte and mineral imbalances

after these losses of body fluid.

The twins were taken to the cage of their mother

during the periods the diarrhea seemed less severe. The

introductory program was not right for them as they were

unable to react in a positive manner. It was decided to

introduce only one orangutan at a time for reasons of

safety. If one orangutan was injured, another would still

be whole and healthy saving the possibility of endangering

two rare animals at one time. Both orangutans reacted in

the same manner when placed in the cage. Jennie appeared to

understand that these were infant orangutans but apparently

they had outgrown her level of mothering. Jennie would walk

about the cage masticating food and leaving it in piles for

the baby but the baby would not know how to respond. Both

Melati and Mewar would huddle on the floor of the cage,

making as little movement as possible and remain there until

a keeper would finally come in and remove them. Jennie

would sometimes walk up and touch an infant but make no

effort to pick it up. It came about that the infants were

never really introduced to Jennie as babies. Everyone was 131 too afraid to leave an infant in the cage with her for fear that some injury might occur and none of the keepers had the time to sit all day and observe how long it might take for one of the twins to begin to respond to Jennie's efforts at mothering.

During this same period of time, the twins occasionally were placed in the same cage area during cage cleaning time. They seemed to be conditioned not to interact with each other as they had when they had spent all their time together. The twins appeared not to notice each other, never came near each other and spent their time at opposite ends of the cage eatir, i or fingering the cage walls. There was never indication of clinging or tantrums, just an attitude of silence, withdrawal and preoccupation on the part of each animal.

CAGE — FORTY-SEVEN THROUGH FIFTY-TWO WEEKS

By necessity, Melati and Mewar were moved to a large cage in the Great Ape House so their own cage could be renovated to accommodate a hand-reared baby gorilla. This large cage had been Jennie's cage and Jennie was relocated in the next cage where the twins could see her through the bars. By now the twins had grown so large that they could not squeeze through the bars as they might have done previously.

The large cage was much better for exercise and

locomotion as there were vertical bars for the twins to 132

climb as well as bars across the ceiling from which they could hang. Again, no play equipment was added and none of

the features suggested by Barbara Harrisson were considered.

The twins still did not interact socially with each other.

When one animal moved to the area of her sister, her sister would move on until a reasonable space existed between the

two.

The twins were finally able to climb above the ground level and seemed to spend the majority of their time

climbing and hanging upside down from the ceiling. At this

cage transition period, the outside excursions were stopped.

The twins were becoming too large to manage and had never

ceased pinching and biting the attendants. The familiar

attendants who had been with the twins since the nursery

period were transferred to other areas of the zoo and the

twins were cared for in the routine manner all other apes were cared for by the regular staff.

This large cage could not accommodate time-lapse

equipment and so there are no records of night activities or

time spent in locomotion and play. Since they were never

taken outside again, there will never be any indication of

how sophisticated Melati's quadrupedal gait finally became.

A camera would have been useful at the end of this study to

record the sequence of a very tragic event. At the end of

this study, when the twins were nearly twelve months old, a

thin, pliable rope was placed in the cage for the twins to

play with. Although the Head Keeper had been present when 133

Barbara Harrisson had advised against ever allowing apes to use thin ropes, he had regardless, ordered one to be placed

in the cage. One morning, shortly after, Mewar was found hanging with the rope around her neck. She had been dead

for several hours.

YEAR TWO — SIGNIFICANT EVENTS

I will mention a few events that occurred after the end of the study during Melati's second year as an update

regarding the status of establishing a breeding colony.

Jennie successfully gave birth to another infant female

during the following spring. It was hoped that Melati in

the next cage could observe infant rearing behavior and become familiar with wild-born motherhood patterns. Jennie was a kind and gentle mother to her new baby but was made

extremely nervous by the observers about her. The zoo staff was so fearful that she would harm the new baby in some way

that someone was always on hand to rescue the baby.

Although the helpers hid and tried to be unobtrusive, Jennie

knew they were there and began to chew areas of skin and

flesh off one of her wrists. She carried the infant about

carefully, patted it on the back and shook it about gently

the way human mothers are observed to do. She was so

restless, however, that the baby could not stay at the

nursing position long enough to receive nourishment.

Finally the baby was taken from her and shipped to another

zoo for hand-rearing. 134

Later the same spring, a young female was added to the zoo's collection as a mate for At]eh, Jennie's juvenile son. This young female had grown up in an orangutan family colony at Yerkes Primate Center and was confident in interacting with other orangutans. She was very lively, playful and motivated and seemed to motivate the orangutans in the adjoining cages. All existing orangutans, including

Melati, seemed stimulated by her presence and began to be more active. Almost at once she began to exhibit courting behavior toward Atjeh, although it was felt that she was still probably too young to conceive and bear young. This seemed a good opportunity for Melati to observe courting behavior and to assimilate this behavior to be used during maturity. This was not to be, however, as Melati was sold to another zoo.

There is still no breeding colony or family colony of orangutans at the National Zoological Park. The orangutans are still on a paired basis with each orangutan having one mate selected by the zoo and not by natural selection. Under these circumstances it does not seem worthwhile to have special hand-rearing programs or family réintroduction programs if there is no plan to maintain the animal for a breeding program. If an animal is reared mainly to be exhibited, then any rearing program will suit

that purpose. The Head Keeper has retired and has been

replaced by a more educated person with regard to ape care. 135

During my most recent trip to the zoo I noticed that the orangutans are now permitted to have straw in their cages for manipulation and to lie upon. Chapter 4

GROWTH AND DEVELOPMENT PATTERNS OF INFANT APES

Trends in growth and development vary among species of primates. Among individuals within a species there is also considerable variation, not only in growth and development patterns but in eating habits and accompanying behavior. Figure 17 demonstrates the difference in intake between Melati and Mewar. When viewing this figure alone, it appears that considerable difference occurred in milk and solid food consumption between the two orangutans. When comparing these patterns with those of two hand-reared gorilla infants (Figure 19) we see marked variation in feeding habits between the pair of gorillas and between the two pairs of apes. Mgeni Mopaya and Tomoko were half-brothers born at the National Zoological Park in

Washington, D.C. and hand-reared by the same person until they were ready for cage introduction. For Tomoko's developmental information see the publication by Carmichael,

Kraus and Reed (1961). Mgeni's developmental information was taken from my own observational study which occurred simultaneously with a portion of the study of the orangutan twins. According to intake information, the orangutans and

Mgeni drank considerably more milk than Tomoko. Unlike the orangutans, Mgeni took more milk as he grew older and the

135 136 introduction of solid foods (not shown) did not seem to affect his liquid intake. The orangutans began to decrease their milk intake with the addition of solid foods so that their intake increased with age and growth but the intake was a combination of milk and solids and the milk intake actually decreased somewhat. Increased intake seemed to be correlated with the size of the animal in each pair. Mgeni was larger and grew faster than Tomoko and the same pattern holds true for Mewar.

Dentition patterns hardly varied at all for the twins because their teeth erupted only days apart from one another. Their dentition pattern was markedly different from the pattern demonstrated in one of Barbara Harrisson's

(1963a) publications of confiscated orangutan infants. The dentition chart in her book shows tooth eruption occurring at a much later date than the recorded eruption for the orangutan twins. This may have been the direct result of malnutrition as the infants had never been given milk to drink but had existed on a rice and rice water diet. When compared with gorilla dentition patterns (Table IV) it is evident that gorillas have many teeth by the end of the first six months compared to the number erupted by orangutans during that period of time.

Species-specific comparison of growth rates between the orangutans at the National Zoological Park and two hand-reared infant orangutans at the San Diego Zoo (Figure

18) probably reveals more information about hand-rearing 137 methods than variability in orangutans. Each pair of

animals is nearly parallel in growth rate. Each pair was probably fed differently so that there is variability between members of a pair but the variability between the

growth trends shown by each pair probably accounts for differences in hand-rearing methods.

Individual growth patterns were researched with

computer aid. Throughout the nursery period measurements were made on a weekly basis. These measurements were

compared with one another to determine specific sites of

growth at any given time by using the Statistical Package

for Social Sciences to make scattergrams of 40 variables.

Examination and comparison of a pair of measurements on the usual bivariate scattergram shows the two obviously

correlated with a long ellipse in almost every case. All

correlations are high, which might be expected.

Figures 20, 23, 24, 25 and 26 demonstrate Mewar

growing faster than Melati and always being larger in terms

of head and chest circumference, upper and lower arm length

and upper leg length (Mewar is always the symbol on the

right). All these comparisons show correlations between .9

and .7 with a significance of 0.00001. According to

Figures 21 and 22 Mewar started at birth with a taller head

and spine than Melati. Mewar then attained a stable

measurement or growth arrest in those areas allowing Melati

to grow until she also reached the same measurement and

stabilized. During the 15th week Melati's spine measurement 138 corresponded to that of Mewar's and at the 19th week

Melati's head to spine measurement stabilized. In both

cases Mewar reached a stable measurement faster than Melati

and Melati followed the same pattern, although it took her

longer to do so. When comparing Figures 21 and 22, it becomes obvious that length pertaining to spine and head growth is more dependent on head growth as the spine retains

the same measurements at 13 weeks for Mewar and 15 weeks for

Melati. Overall length does not cease until 18 weeks for

Mewar and 20 weeks for Melati. This difference accounts for

increase in head length. Reading the meaning of the length measurement from the correlation of its scores with the

original measurements shows that the differentiation lies

strongly in the head measurement (Figure 29: correlation

0.95810; significance 0.00001).

Other body measurements also show positive

correlation along with high significance. At the time the

head length accounted for the major increase in length of

the orangutan, the head circumference was also involved in

active, rapid growth (Figure 28).

Figures 26 and 27 demonstrate limited upper leg

growth and minimal lower leg growth for both animals. This

pattern is also demonstrated in a different manner by

Figure 38 correlating the relative size of the upper and

lower leg. When the upper and lower arm measurements are

added, they appear as important patterns in the greatest

distinction to be found among this set of growth trends. 139

Orangutans are accustomed to a vertical position. Their

legs are much shorter than their arms and cannot be fully extended at the hip or knees in adult life (for anatomical descriptions see Napier and Napier 1967). When orangutans knuckle-walk on the ground, a portion of their weight is

supported by their long arms and hands. Tuttle (1967; 1968;

1969) and his associates (Tuttle and Beck 1972; Oxnard and

Tuttle 1969) have actively studied hand and knuckle function in orangutans for many years. According to Figures 35, 36,

37, and 38 it would appear that this growth pattern of

longer arms begins in infancy. Figure 3 4 demonstrates

faster upper arm growth than forearm growth but the combined growth of the upper arm and forearm is faster than the combined growth of the upper and lower leg. When compared

to spine and head length, however, the rate of growth of the

arms and legs was not as rapid as that of body length

(Figures 30, 31, 32 and 33) .

Since Melati and Mewar were not exercised as vigorously as a wild-born orangutan would have been, it is

difficult to assess the normalcy of the growth patterns of

the arms and legs. Figure 26 of the upper leg shows growth

increase at the time the infants began to try to crawl

although upper and lower arm growth trends (Figures 24 and

25) do not reflect growth accelleration corresponding with

increased cling and swinging activities.

Although many other measurements were subjected to

computer analysis, the scattergrams shown in this chapter 140 demonstrated the most striking trends of growth for the orangutan twins. It is clear that patterns of difference between rates of growth are compounds of certain specific patterns of variation among individual rates of growth and of a limited number of such patterns. These statistics are most successful when they tell us what we already know but also teel us more by arranging material as we cannot do by intuition. 141

ro VD u m 1—( CN s X X X X X X X X O X X X o X X >1 >1 > i 0) 0 0 0 S T) •O XI

-H CN Tf +J 1—1 r—1 nj X! x x x x x O X X XXX XXX I—I >1 >i (U 0 0 s "O "O

O 1—i (N m 'ij' G (U 0 g •H 44 •H ta to o G a 44 a 0 0 44 •H G M G 0 m G 'O 0 E 0 O 0 0 Oi W G a G 0 > G m Oi U) 0 a 0 E O a G g 0 0 •H 43 43 M 0 G G « 44 44 -H rH G o Xi •H a G 43 G O G 0 -H Oi O m O 0 0 G X) u G m 44 0 g G 43 Ol g G 1 .. CJ rH O ^ O 0 44 G G 0 44 0 44 rn w ü 43 -H -H 0 G, 0 0 G 43 Ol 0 44 > rH G jG 0 1—l 0 -H G 0 0 to 0 0) •H 44 3 t o M G W > >1 ■O 44 'O 0 -H 0 0 s 43 O 0 -Ol G 01 43 ü G Oi a 43 O G 0 G 44 0 0 44 0) 'Ü G 44 O •iH "H 4h iH H ■H Oi tSl X W W G 0 G G a 0 TJ 0 G G 44 0 0 G O > G 0 o. 43 0 M G ■r4 G H 44 0 4H 0 0 43 "H 43 -P 44 T) T3 0 0 G G > G G ü 44 44 G iH 43 G 0 4< 0 G 0 g 0 0 0 0 *o O O 01 O G E O iH G m 0 Æ g D. 43 G -H 43 G -H G ‘ O *H *H 0 > O 0 44 O 44 44 10 X) 44 43 LH 0 44 C Oi » •H G G 0 ü E 43 •H S G O 44 M 0 G H W -H 43 Z •H G 0 W 44 4^ 0 Æ •H O *0 O 44 a 0 O 0 LH 43 0 O > > 44 0 a 4 4 0 0 G a t 3 o G ü U4 44 0 43 G Ü 43 O G O •H 0 h G S m ü 0 0 •H 44 44 O 0 0 44 43 0 0 T3 43 O 0 G G *0 rH MH G G 0 44 0 G G ü *r4 0 > 0 •G G 43 44 0 0 •H O 0 tfl O 0 0 44 H 44 a 0 G O to Ol a a 4 4 43 G P g ü s 0 G 44 a G G >. G ü 0 X c a m 0 0 o n 0 W 44 to O *H 0 0 0 43 0) ■H H 44 0 rH G 0 0 T) a to H X) X) 44 w 1—1 G P (0 G ■H Di 0 0 43 G M G a O -H G 0 c «w Oi 0 0 O G 44 44 44 0 0 44 0 0 G o (U « 43 •‘ 0 144 -H ra tQ •H G *H n •H •H s >1 G r-4 iH "O 0 -H O G S V, 0 g X3 44 4-> 4< _ 43 0 44 o >H -H G ra 44 a o 0 iH G 0 0 0 ü ai o P 43 G 44 G iH 0 m g G O G 0 0 < G O G m 44 0 CL 0 G 0 0 - U to G 44 43 44 •H w 0 0 44 •O >1 CL G 0 m a a iQ > Di W 0 1 0 O G ü , o o X) 44 43 c U 'O 0 iH O G g 44 tO G to 44 G Ë 0 44 44 nj 0 13 0 0 44 0 0 G 0 O 0 0 U O 0 -H -H u 0 43 W 'O 0 G 0 G *0 a G •H TJ 0 G 43 G •H ■H t4 Oi 0 0 B 44 O 0 -H -H (d p +J iQ i43 «H G 44 ■H 44 G G G 43 G m W « tu (l4 O S M 2 pq E4 < à < a Eh ÈH

Ol o Ol Ol o u CN in in in to vn X X X XXXOXXXX < o o X X X >1 i 0 0 0 0 0 s X3 XI XI XI XI 0

•H m 4-1 m 0 X o XXOXOOXX X X X H >. >1 0 0 0 S XI XJ

0 m VD 00 01 2

43i rH XI 0 0 0 0 g 0 0 G E •H g 44 0 •H P •H PP 44 01 >. XJ o G rH P G XJ ■H rH 0 O G 44 0 G O •H 'S 0 U •H 0 G 0 0 •H P 0 P G p 4-) G 0 0 0 0 0 G G G > P P P a •H 0 XJ G G G-H rH ü G O O O 0 0 (fl HH 14H 1»4 XJ XJ u 44 0 0 G >1 G G 0 G XI H O O GX ê 0 G H "H "H 'H *H o 0 0 P P p p _ G P P 0 44 43 P -H 'H •H -H G P G 0 G 44 G 0 0 0 0 0 •H Ol 0 G o 43 Ol O O O O O a S -H a G o XJ 44 G N a aa a >1 G 3 0 0 0 •H ■H 0 •H 0 0 43 O' 0 0 rH 0 G 0 0 0 0 H P 0 G 0 H G 44 X O G G G G a G P 0 XJ G ri ■g ü 0 0 43 H "iH -ri -H 0 0 G 0 ü 43 44 G 5 ■H a a a a G P g P 5 •H m O •H 44 •H G 3 o 0 OH O 0 P G G G 44 44 P 0 0 0 0 0 > 0 G 0 0 ax3 o •H O G 0 •n 0 rH 0 a G § il 44 G o o o o G G g G >1 0 44 44 G p p p p % O O - P Oip  *H -r| G 0 0 43 P ■H P 0 G G G 44 X3 ü O 0 «44 U o (1) Q) (U (U G P G G >1 0 •H O 0 0 0 0 G G 44 P G G 0 Ü 0 0 0 a •H G rH 0 a 0 0 o P 0 a < p s > 0 a 0 43 •H G 0 E g il S S 0 0 0 G 0 ar-t O 44 Ol 0 a a a a G XJ XJ 0 -ri XJ 0 G 0 H a 44 44 -H G 0 OiP p 0 0 G >fXJ -H P U P a44 ü G -H g g g g mh o 0 0 0 0 H H T3 0 •H iH H o o o o a Ol o> 0 G Ol G H 0 a G M G G G G 01 G Ol C Ol G y 0 G O H U XJ XJ > XJ XJ XJ XJ G p > 0 0 H ü I P 'H t) -H O •H y. 0 0 o 0 0 0 0 0 0 0 0 3 H S G G G 0 g 0 G XJ u rH H H C G G G G 0 G O rH nj 0 0 G 0 TH S rH 44 rH •H H arH rH G G G G 0 n 0 o 0 G 0 G 0 +4 0 G 43 G O 44 g •H O 0 3 3 3 3 0 0 CQ a a U to u U 01 P3 Ü < H w O) to h3 a a EH E4 Eh Eh to a 143

u Ol X % X X X X X x x x x x x x x x x x x x I 0 g

■H p 0 o X X X X XX xxxxx xxxxxxxx «H g

0 CN n

2

ü p 0 E •H P

G P G I 3 01 O G P •iH 0

•S’S X P 0 u •rH i P rq P 0 G 13 0 0 - G -H 0 E p 0 ■H G 13 o u 0 P P ■H O 0 a 0 G • n O G G G G O O 3 O P P 13 a ; G 13 0 G G ü 0 0 P O O 0 •H G ü ü p 0 0 0 P P 0 G P n •H -H P G G 0 0 0 I o O G "S'S O O o H *rH a a 5 G P P G Ol u jQ "iH •H 0 G O G t H 0 0 G 0 0 P G G G 0 0 0 8^S iH 0 0 G O *H Ol 1 a G P >1*0 a ^ «H G a G 13 0 ^ G t—I G •H 0 a 3 13 •H 0 01 01 O P P iH 0 P rH G 0 0 P P 13 G 0 G 0 G •H o 3 3 G 3 G 0 o P 0 0 G ■H G •H P O P O 0 0 0 0 p o 0 Ol 13 -H 0 iH 3 13 •H O iG 0 - G G •H •H G H iH G 0 o 0 G P 0 0 P O t> P G 0 P P H 0 G 0 P O •H •H ■H •H 0 O 0 G 0 •H ü G 0 H G a a > ⧠S P G G -H G G 0 g 3 p 0 X H 0 0 Ü 0 0 •H G m ü rH a 0 0 Si G < g §-2 0 0 •H 0 0 0 0 G 0 0 a O O G 0 a 0 p 0 Ol 0 •H •a 0 0 G p G G rH O P G u I 13 0 P S ü 0 o •H 0 ■H G 0 g 1 •H > G >1 O 0 iH 3 0 G Ü 8 Ol 0 a 0 o 0 G O o G L G P P p Ol Ol 3 3 0 X oip a O 0 Ol 5 G ■H > G ^ u G . 0 Ol G 0 3 G u 13 Ol H G H u u i3 0 0 G •H G 0 > G T) H 0 0 Ol U 0 a 0 0 0 Ë P O 1 H G O G 0 P 0 H G G G •S’S p 0 0 rH G iH3GG0iüiH-H C p rH G G •rH 3 o 0 rH0OTHG0aa -S 0 0 3 3 3 f—I ■b '3 G 3 3 0 arH 0 0X 3 m Eh Z a EH Eh U EH PQ u u ü a a acMumawto 144

O 00 u rH X O X XXXXX X X X o X X X X X 0 0 I 0 0 S ?

•H P 0 X X X X X o X X X o X X X X o X X X X H 0 g

in œ Ol o (N G 0 •H P -H tn 0 a 01 G W -H H p •H p P 0 •H 0 G 0 G G ■H 0 13 E p •H G 0 P 0 G G •H P 13 0 0 0 G 0 G 0 O 0 13 G G 0 0 a G G 0 0 0 G 0 13 P -H ü Ol G & iH 0 ü G 0 G •H •H G P •iH 0 a 3 0 -H 0 P P P 3 0 CP 0 G 13 rH 0 0 •H 0 0 H 3 P G 0 a P G 0 P G 0 <• G 0 "H -H G -H O G •H y 0 0 P ÿ 13 iH 0 0 0 13 U H 0 E i G 0 0 0 0 •H 0 0 G rH -H •H G o p E 13 •H 13 ü H P 0 0 a P 0 P 0 o 0 G ü G p G E 13 G 0 G -H •H G O 0 0 P •H 0 0 0 G •H G *iH a 0 u > iG 0 > ü P S 3 0 fH a 0 G G G G 0 U O a rH a 0 rH 3 0 0 0 ■H 0 ’H 0 1—1 0 r i 0 0 G G G P P P 13 G G •H 01 13 H G X 0 o 0 -H P P 13 G 0 13 3 P •H 0 0 0 13 G 13 G -H 0 -H E 0 13 O P g p G •H 0 Ol S E 13 g G G G G P 0 a G -H 0 G 0 0 0 0 0 O 0 P 0 0 G 0 G 0 0 G 0 0 •H ÜG 3 -H -H G 0 P a 0 o 0 ■H a G P G 0 0 13 > 13 0 a a a P 13 P p U 0 rH 13 P 0 G Ol a 01 3 a G •H 0 -H < ■H 0 0 G P G 0 G 3 G 3 G 0 > G > > 13 13 0 •H 0 0 0 •H P 0 G •ri O 13 0 0 •H 13 G P G P G G P •H P G P G G a 0 *rl 0 0 P P P 3 O iP P G ü a 3 0 0 G 0 H G 0 0 0 0 13 •H 0 •H 0 0 o G 13 3 P G 0 > rH rH G rH 0 0 U 0 3 0 -H 'H Ol 0 0 Ol G Ol O g 0 Ol 0 P P 0 G E a . G 0 0 G •H 3 0 G G 0 0 •• ‘H •• 3 ■H P 0 'H G 0 •H G o ü 0 G p G G G G 0 rH 0 0 g G % P G P 0 p H G P 0 P P P P G > G G 3 Ü G G ü P A i E 13 Ol 0 0 0 G 0 0 0 0 0 0 0 0 0 0 G•H 0 0 G Ol 0 G 0 0 0 0 G G 0 G 0 0 m EH H W Eh a H Eh O ÈH EH Eh Eh a U EH EH C a 145

TABLE II. DIET OF HAND-REARED ORANGUTANS 0-7 MONTHS OF AGE. NATIONAL ZOOLOGICAL PARK, WASHINGTON, D.C.

Type of Food (Gerbers Strained) Medication Day

Prosobee Hypoltye: 5% Dextrose 4 Rice cereal (flakes) 18 Vitamins 21 Applesauce 23 Mixed cereal (jar) 43 Vegetables and beef 43 Sweet potatoes 44 Carrots 52 Water 57 Beef 68 Cereal, egg yolks and bacon 72 Chicken with vegetables 73 Peaches 74 Oatmeal 78 Cereal with apple and banana 78 Probana 99 Apple juice 99 Orange juice Corilan (Mewar) 100 Tetracycline 130 Banana 136 Kaopectate 137 Cottage cheese with pineapple 153 Orange pudding 158 Fruit cocktail 160 Kanana banana 165 Meat sticks 168 Tinned pears 174 Blueberries 175 Fruit 176 Egg yolks in milk 176 146

TABLE III. DIETARY ADDITIONS FOR HAND-REARED, CAGED ORANGUTANS AGE 8-12 MONTHS. NATIONAL ZOOLOGICAL PARK, WASHINGTON, D.C.

Type of Food Medication Day

Custard Kao-Con 221 Paregoric 221 Fruit (orange slices, bananas. Biosol 221 apple slices, grapes, plums) Sparine, \ tablet 221 Fruit mounds left in cage 227 overnight Butter Sandwiches 227 Banana Peel 227 Aspirin 282 Liquiprin 286 147

oooinooœ^rHr'œinœo intop-t^œmmHCNmr'Oo M 0 IS'(r Q H 0 g < •H u 0 o y I o m P in rH fH VO (Tl o o (N (N m m ^ r f VO IT) o o 1a rH rH I Eh I Q " a ^ G p i « 0 >1 r~ 00 H» m <4> rH D ' 0 ) 0 rH iH (N m m in O B G 0 Q rH 1—! rH rH iH f—1 k O 0 g Eh p Z O 3 H S en H G •H en z 0 p z tn G 0 > i o r~ in CN CNO S < w O I—i 0 CM rH m en in eo O 0 Û rH rH rH rH rH rH EH EH g g eu en § K sa EH eu o D H Pi O I M O vo HÎ I m rH Eh O O Eh I ë z o G en O •H P G G ■H G G G O G o II 0 GOG O 0 0 0 0 OO 0 o 0 0 •H 0 •H eu 0 •H 0 “H •H ü •rH G G •H t4 •H U ü G O G 0 0 t ü G U G G •H G •H H rH G G •H G •H "r| •fH 0 •H•H rH rH rH 1—1 0 rH i i G rH 0 rH 0 0 G 0 p p P 0 •H 0 •H G 0 G 0 P P 0 O r l rq •H TJ 0 P 0 G 0 0 G O T3 0 T l 0 P 0 P ■iHG G •iH g Eh 0 E 0 Ë 0 rH 0 P ■H "H P e E rH rp P P g P G G G G G G O G 0 G 0 G 0 G 0 G G 0 > 0 eu 0 Çh 0 CL 0 0 0 & O eu eu eu Qc â i I eu 0 rH eu 3 eu 3 0 Mg'&g >i rH 3 3 t—f EH p p P P G P G P G P G G P P P t n p tn P tn p en u ip p 0 •rt 0 •H 0 ■H 0 •H -H 0 0 Pi Pi n; Pi ^4 Pi P i G G 148

TABLE V. INTRODUCTION OF FOODS TO TWO HAND-REARED GORILLAS AGE 0-14 WEEKS. NATIONAL ZOOLOGICAL PARK, WASHINGTON, D.C.

Foods Introduced Tomoko Mgeni

Day Day

*Applejuice 21 Applesauce 27 18 Banana 76 Bremil 1 17 Cereal, mixed 23 Cereal, mixed with fruit 24 Cereal, rice 6 Custard 17 11 Dessert, fruit 75 Dessert, pineapple 88 Dessert, plum 88 Eggs, cereal, bacon 27 67 Green beans 28 43 Hi Pro 1 Oatmeal 61 21 Orange juice 16 Pablum 14 Peaches 34 68 Pears 33 45 Peas 70 Plums 75 Squash 27 59 Sweet potatoes 62 44 Vegetables and beef 46 61 Vegetables and chicken 67 85 Vegetables and lamb 71 Vegetables, mixed 65 Vitamins 5 8 Water 4

* All foods above are strained commercial preparations for human infants. At this age no fresh produce was introduced. 149

\\T \W W x W W W W

\ \ \ \ \ V \ ^ s s s s

w W x v ^

\ \ v \ \ \ \ w ^ CN G \V \\\V V \V ÿ^ 0 0 s:\x\v^xvÿ^ Ai eu

*q en

:cO 1 g. g

^ c* 5238 arials 2 3 a % f! $ 2 a (3 25 saONûo 150

o

V) o

o

co m u3

sO

UN

C O O • m p

o o <:

SOMOcî -d- f- ■ >o u\ H H 151

+J ni w

rH

GO

H Q

O M in I—1 ni •H !S

w H

iH

O m •H pH

0) 5 152

+j x: W CP C •H nJ 4J G CnE O d

O W-l > O EH «1 VK> Ciwm 10 • OJ o m < '^C3 rg > UJCtC^ tt:c\ • m VD M CM 1 1 1 o 1 4 E ' u. 1 t7> VO \. CJ r KÏ •H -a r :.•« o C5 ti­ S' O cjC

0£ Hf rj ro 3 W CV rv IV rv> Ü C *- \».t- J - t (T Cl ll 153

0) d •H A M

lU U ü t) 3 (tJ Ul 0) f: 0 p m r u' o m J. * E x: tP ■p CJ tp U c A (U r-t E O P • ■ «H W c CJ nj en P 3 3 &>M-l C o (t U 10 0 CJ p CJ c > d p vo c CM •H 1 u> O s E « EH O J —J P p Un x3 c l.JKl « tp I— 1 (0 •H P P C 0) CJ C U E o 3 O tP p p ■ri 3 ta u pLi (0 > ï ■» > rtj CJ CJ S A o x • s (T ij) rï OJ i' L ‘H.

rS 154

E O u p to p c

►^U Ü.W 155

CO 4 r- 4J 1 4 G I I o IM I '0 3 I 4 CO I td I QJ B :: I 4 I

Il oO t • ♦I 4CM H 4I # * 3 *- t_'4 I I o *I o* I w4 I * 1 12 ♦I u.• I ro *I I I* o * « t 'X. I rO 4-I 4 I I ou ♦I 4 # • ro I ♦ I I u9 ♦I CM • Ir $t OUJXl I L $ c> I Cl O tI a# I K) u/r.'o ncO • I W'f (T^ w CM I I Ao u ♦ 1 U 'f : 4X r % o o CJ o OK o O O o 4 ^ e • #- cr VD 4 N CM vD a Ui N CM CM cv c y 156

ta P C 0) E 0} P 3 m (d 0) E f : ptP d 0) 1— 1

Ë P td

P O 0) er’o C ‘C CL CL 3 •

P •* £ 01 tP d 3 P p 3 d tPo d (d p P as o > 0) p S d id p û) d tp •H (d

O P S 0 Eh X01 • (U 'a* eu (M S: 4^0 U 0 0 (U VO fto « P (M 3tpvo1 * •H • * ¥ E O p p 157

t-H »

P «• A V) tP C •H nJ P P 3 d tP 0 d (d p M fd O 0) P S d id p d) d tP •H td

0 p s o EH co C<: îeOJ M • d) in (U (N > < lo L O o OJ vo «Ci • P (N 3 1 1 1 1 1 # 1 & «3 L ♦ 1 1 •H U O * >4» «1 1 l-m * g 41 3. 4 g. g O — CJ.lï CJ p i" O p >- K \a

L 4-

*->LJ Ü CO 158

§ P p U) P C

pi 3 to 3 e tp 0)

iO ûrcjC

to c • (d P P 3 Æ tP tP d •H (d P p 0 d 0 p d p (d td p S d dJ •H S 0 > d) Eh tp td c. W*-4 • p Ur vo O CN (0 4 Tve (U KO * p d) U"*# 3 d)

1 ( 1 1 1 + • •î* k vo 4 > CM : 4 c> OK I 4 Z'C VD K r c ►- U h- Vi K r-U C3 U LO 159

< Ê i O < p p co t p d t tu i c e l 'î tu p 1 3 1 to 1 nJ 1 tu e en tu 1 1—1 1 P (U s 1 o 1 p 1 1

î l! 10 1 <•.' d 1 (d P 1 3 1 O en d td 1 P 1 o d 1 O 1 P d td 1 rj p 1 d •H I 1 0 (U g 1 g p r - o CM to tu M p 1 1 •P 1 1 u . ♦ 1 tP VO L w O (M X I O o C I vo O n e a e

►- (£ vn 4 CM U r CM rvj CM c** 1" L # - ? c - t U C’ l l M 160

I n I 4 I I I I m u: O I r- I xT I I ♦ tI I o ü « » o + # U 0) ■H tr> 1 xD U (d

I T) p I (d O I c: I LJ QJ * # (0 I fC f : I M- I p (U • I l/l • 0 QJ S d I: o VD • *4 to CN I xf •H 1 M VD (d CL 6 E O # 0 O P I U ü P I

• • to G to (d o •t uf- p p t 3 u tn (d ■—' • I d I (d I o I o p Xî *I m• O p I U' en I p d d 0) M ün (d p p * o d 0) I m H d •I u» •H I A I- fc • 1 to C.L^UY # I 00 I: CN jd * # p I #4 I W) tu p I P S I 3 *4 in en 1 1 1 C3 ■H d 1 # 1 U u. * 1 ? U.O 0 £ 4 4 r S r 4 O ï: One O O O ;-Lî 1- (K (p xA tn CM Ui lO fO K" M Kl 11 k- L k— _J4 ne #4L) c- Ü.W 161

C P vT 0

CJ d *H CL V) rt T3 CJ I f CÎ O' v£J nj d

m nJ o c :

** CO d cn CJ d o r - p p U'' 3 u cn d d '— " d PX: o p m O' u i p d CJ • 1 d d p a P d 0) K3 IT CL • to *t 4 fV 4-) OJ -H L.uicaCIO KO • CJwO

u ♦ « I , / C l • ^ i 4 Td e CP OK CJ I» K1 f u xA K> U*3 1Ü 4 4 m K1 L M _J4 *-*CJ 162

Xi p cn c 0) 1—i

(U (3 • •H U Cl * • o a. **' 4ÏV

4 1 i 1 î» t X: 1 I P p # p P 1 tn 1 1 1 P c 1 1 1 1 « 1 f 0) 1 1 1 1 1 1 — 1 1 (U 1 1 P t 1 1 c « -H QJ • 1 1 * 1 1 CL tn # r f 1 (/] d • « 1 ir 1 TI p 1 • 1 C O 1 1 I 1 d 1 1 1 1 1 1 Ui 1 1 1 # d Q) ^ £ CM 1 1 i d QJ I P K 1 1 x: S 3: C=r 1 « • 1 (L p vo r 1 P ! * p < 0 (N 1 [ P P p c VO 1 p 1 1 o CQ Ë 1 C-f • 4 < •H O 1 1 P P P 1 1 t î 1 1 d P 1 CL 1 1 1 1 E 1 p 1 1 Ci 1 * O W 1 1 * P U Ui 1 1 o 1 • 1 1 p 1 1 1 «• • 1 ü r C d P ♦ r- p P d • I I 1 P t I P * 3 X: tn P 1 1 P i 1 • t i o C tn * d « G 1 t 1 U'. p QJ 1 i CM o f—1 1 1 É 1 1 1 # 1 1 p g 1 1 1 1 p 1 I 1 1 G 1 1 1 d d 1 1 p 1 P p 1 I CM G ! t 1 P H QJ 1 1 1 P 1 S « I M O i 1 • 1 i O 1 1 • •1—1 c « 1 ! -'I 1 P o 1 1 1 1 n XI I « p 1 1 1 1 •H twCG t • QJ iro « 1 1 4 1 P > t î • 3 1 tn 1 1 o 1 » ♦ * •H d u c a. k S % * O i ’ 4 T( «ty OK h- rr 3 Ll Ü) »- y L:r- 4 _j4 or M U e« iptn 164

+j Di C (U «—I (U c • ■H (D Û4 Ol (0 re ft3 V-l C o HJ w •d nj o (U (Ü & m VD O tN t c U) o 0:0 w E I'C, •H o M HJ IN a. e o cn Ü w o N • • Ü G (0 '—' jj d C71 +J c tr« G u o 1—) 4J tji G Q) (0 1—1 •4-i G H (U a a • 3 (N ro rC +J flJ •N b O o h > (to * G Cn 1 1 1 1 •H G b 4 # ♦ « > b o O < v r < y O i r O O 2 nr KÏ CM f" m 3 Lf ♦ t' #- U - J ^ t - U n Ü

o J +j f; I * ♦ (n fC.'f I G I (ü i 1—1 ♦ I c I (U r : I G « • ♦ •H d K. It a en to (tJ #I T3 M-l C i I G 0 es I * 4 c I ► * 4 m u> VC I 0 04 t I 1 V ♦ G t£> tr I c t 0 Cr-O I tn E (-.'C-= * ♦I •H o Wtl I M p Kï I (ti Ip a I e I o to C, I CJ I u to • 4 a j 0 Py 1 p I u # G d ttJ O I -P I 3 Æ C I , tn +j rj I G tn I I d G 4 M (U I • O H CJ I o I • 4 -P tn < t W I G tu I 3 rH I tH I G p II • O I H O) u. o • K CJ I ) « «CM I 0 C (/3CM I • H C • n i m Æ I- I #I -P «t 0 * ^ 0 • ■*-’ CM» a 3 1 a 1 o tn 1 a U 4 • 4 # •H G l* C' > *L 0 y « o TJ r' CJOC o O -•c*» 1— K CM (T lO rt 3 UJ •e 1“ *- i' L 4- -J«K l— O c b V> 166

x: +j en G • (U m 1—1 tn m o in ^ 4-) M td 0

p en 0) M a 0) fO a oj Ki 3 s m VD 0 (N 1 C- G VD Kï O m e *H 0 P P td M-i a • 6 0 w ü tn 0 ' P ; p " ü G 3 4- td ' CM -P 3 Æ tn 4-1 G tn td G P (U O < - \

4-1 Ë p; G p %»4 td td C, v p G P II M <ü S O • 1—1 g H* m Xi rH fM 4-1 bJC'CO«t'C O Q) -H o:u # P S 3 O c a •H G k S 0 Otj' t ) i*iî

MlJ_r«i u to 167

1 x: 1 f-4 -p 1 tn c • 1 (U 1 3 Ü ♦ • tn -—- L-O ■H G X k S : -1 g o o a o •d U) KJ Ui*h“ #—U U.C/1 168

X! -P t* t n fl- G « d ) <ü H t n (d e p 4 4 GO

P tn <ü X 0 ) O 0 ) r H >

4 4 v o O 0 4 1 G v o 0 tn E •H O PP a(d 4 4 Ë 0 en o tn O p «* o G (d (d + 1 3 X ! t n 4-1 G t n 3 G P w O r 4

4-1 t n G 0 ) (d 1—t 4 4 G p H 0a ) a • 3 v o m X! 4 J (U •H tPOO P < r o • 3 t n 1 1 1 1 ■H G U- 1 p t( Lk>0 > k O ?5 t ) CJtx o O a i'tD 4* O' N *0 rH %n tn p Z2t UJ H) K) tn (V IM CM Cî* U'$- « or K - U o k w 169

*

Æ 4-1 tn G • 0) 0) rH tn id

q 44 (d o

u tn (U M S (U o Q] iH 26 44 vo O

G U3 0 01 e •H o P p id 44 ea 0 (0 u to o p *» u G (d G 4-1 3 X i tn 4-1 G tn (d G p d) o rH 44 tn G m (d rH S 44 GP n H m o> < iH 0- m X: 4-1 < t o 1 1 1 (U •H U>C- o 1 1 1 < r C l • ♦ p > 1 K i 3 t : • tn 1 1 •H Il ♦ 1 ♦ • G a > O i*« O •a o m CJ 1 " C • 1 - n : ( T U’ tn o \ 4 - M { 4 p w r- K ï K ï «M cm CM CM fM c U'M r t •“ • C l r * u co 170

x: • 4J t n C • m

fO

« ; * o U l C O 0f*O •

V CJ

1 1 Ü. ♦ ( UIC> A 4 3 « 4 O o r a ; : c »- m K> O' in 3 UJ CM OJ N C* / U < ^ < c r P-U o U

BEHAVIORAL PLASTICITY AND ADAPTABILITY IN HAND-REARED NONHUMAN PRIMATES

There is a vast difference between the behavioral patterns of nonhuman primates that are raised in captivity and those that grow up in the wild. Primates must, necessarily, mold and adapt their behavior to conform with the environment in which they find themselves.

Consequently, there are several factors that influence the behavior of hand-reared primates. Isolation, maternal deprivation and disease are the chief determinants in abnormal captive behavior.

EFFECTS OF ISOLATION ON PRIMATES

It is an accepted fact that society plays a significant role in the survival and propagation of several animal species. While it has been possible to survive by adopting the solitary life— except for brief mating periods— it has also proved something of a dead end (Tiger and Fox 1971:25). Gregariousness is the keynote of primate society and true social systems emerge only when animals can develop contrasting and complementary roles within the group. It is not surprising then that the isolated animals

171 172 of any gregarious species, even if well fed and healthy, become morose and miserable if deprived of contact with those of his kind for very long (Tiger and Fox 1971:197).

Yerkes (1929:565) has pertinently pointed out that

from lemur to man it seems to be increasingly difficult to keep primates healthy and content in captivity. Yerkes goes further to suggest the generalization that the higher

the psychological organization of the primate, the more difficult it becomes to provide satisfactory conditions for

confinement. It is difficult to emphasize adequately the

richness and diversity of inter-animal contact during the

early years of growth and development of all free-ranging primates. The stark, barren poverty of most laboratory

situations in comparison to field environments is very

difficult to convey in words. When we put the social

isolation experiments in juxtaposition to field observations

of social behavior, it makes a very sharp and vivid contrast

(Hamburg 1969:5).

It is a well-documented fact that in primate

evolution, social organization has functioned as biological

adaptation and has helped in heightening the ability of

primates to discriminate and to be selective (Hamburg 1969:5)

David Hamburg points out that this selective advantage of

primates manifests itself primarily in activities related

to; 1) protection against predation; 2) meeting nutritional

requirements; 3) protection against climatic variation;

4) coping with injuries; facilitating reproduction and 173 perhaps above all; 6) preparing the young to meet the requirements and exploit the opportunities of a given environment, whatever its characteristics may be (Hamburg

1968:5). It is beyond doubt that captivity and isolation impair or negate the behavioral patterns that result from social organization, but research and experimentation in this field have only recently been undertaken.

While it is common to assume that captivity and isolation have similar effects (under similar circumstances) on all primates, it must be pointed out that actual experimentation has largely been limited to rhesus monkeys and chimpanzees, because the cost of these primates is less prohibitive than that of larger primates like the gorilla.

The National Institutes of Health to the University of

Wisconsin Primate Laboratory and the Regional Primate

Research Center furnished grants to support the research undertaken to assess the effects of isolation on rhesus monkeys. The research was conducted by Harlow who has outlined the conditions under which the studies were conducted:

Our extreme condition of affectionless upbringing was rearing monkeys in social isolation from birth until various predetermined ages. In isolation there was no opportunity to experience maternal or peer affection or to develop affection for other monkeys. We have employed two conditions of social isolation: monkeys in subtotal isolation were raised in individual wire cages which permitted visual and auditory access to other infants but denied any opportunity for physical interaction. 174

Monkeys in total isolation were raised in individual enclosed sheet-metal chambers which prevented viewing of other monkeys or of humans (Harlow and Harlow 1969:15).

The results of the experiments indicate that total isolates fail to develop species-appropriate social, sexual, aggressive, and maternal behaviors, and instead engage in self-directed disturbance activity; partial isolates develop few appropriate social responses and many abnormal disturbance behaviors during the first year of life (Suomi, Harlow and

Kimball 1971:1171). In order to analyze the results more closely, we shall discuss the impact of isolation on:

(1) individual behavior and (2) social behavior.

(1) It has been established that the individual behavior pattern of primates in isolation is drastically, and sometimes permanently, impaired. There is a marked increase in "non-nutritional orality" (Harlow and Harlow

1969:16) which is mostly directed toward the physical environment or thé animal's own body. Usually the animal has a fixation with a certain part of the body— thumb, fingers, toes, nipple or penis— and while the frequency of this orality is high during the first two years, it gradually tapers off and drops to a normal level by the fifth year of life. Another individual behavior pattern that emerges as a result of isolation is that of "self-clutching" in which monkeys, particularly infants, clasp their bodies and/or heads with their feet and hands. This pattern is highly evident in the first year but diminishes thereafter (Harlow 175

and Harlow 1969:16). Yet another pattern is that of "social

indifference" which often manifests itself in vacant

staring. Not only is the primate unmotivated, but it is

also unresponsive to ordinary stimulation. Sometimes this

social apathy becomes so acute that limbs move around in

such an uncoordinated manner as to suggest that they are not

an integral part of the body; this extreme state is referred

to as "catatonic contracture." One behavior pattern, one with which most zoo-goers are familiar, is that of

repetitive, stereotyped movements such as endlessly pacing

up and down their cages. Systematic aggression is another

behavior pattern that results from isolation, and this may

manifest itself in two directions— against the object (or

person) posing a threat or against the animal's own body.

While external aggression is common among primates, the

self-aggression is distinctly a result of isolation and

manifests itself in compulsive habits such as pinching

precisely the same patch of skin on the chest between the

same fingers hundreds of times a day. Occasionally, such

behavior may become punitive and the animal may chew and tear

at its body until it bleeds. Harlow points out that this

behavior constitutes a complete breakdown and reversal of the

normal defensive response; a monkey normally directs such

threats and aggression at the approaching person, not at

itself (Harlow and Harlow 1962:139).

(2) Isolation also has a tremendous impact on the

social behavior of animals, but this behavior varies in 176 proportion to the period for which the monkeys are isolated.

Monkeys that were socially deprived for the first three months were terrified on release but rapidly adjusted to age-mates (Griffin and Harlow 1966). The study indicated that there were no differences in social threat and no significant differences in play behavior. By contrast, six-month isolates, when introduced to a control group, exhibited no play or social threat during the first two testing months. Thereafter, the frequency of play was low, and was mostly limited to contacts with each other, never with the controls (Harlow and Harlow 1969:18). Twelve months of isolation had an even more devastating impact which was manifested not only in the absence of social behavior, but also in the elimination of individual play, a frequent preliminary to social play. Monkeys that have been

isolated for six months or more show no normal sex behavior, and their attempts at play are mostly inept. There is, however, a marked increase in aggression, particularly in its frequency, and in the abnormality of its direction.

The fallacy persists that primates are naturally aggressive animals, but Pfeiffer has pertinently pointed out that for

free-ranging primates "survival is too serious a business

for the luxury of violent dissention within the ranks. If primates behaved as aggressively in the wild as they do in

cages, they would have been extinct long ago." (Pfeiffer

1969:250). He goes further to emphasize that the striking

point about primates is not the existence of aggression, but 177 the uses and control of aggression. This is precisely what is absent in total isolates who often engage in near suicidal acts of threat against the huge adult males.

Harlow's study indicates that even when the isolates were fearful of juveniles, they attacked and bit them, a response that is seldom seen in socially raised animals. Twelve­ month isolates exhibit fear of all social contacts and show no play or sex behavior (Harlow and Harlow 1969:18).

Before concluding the analysis on the effects of total isolation on monkeys, it must be emphasized that the results are directly related to the duration of the imposed deprivation and the degree of isolation. Three months of isolation, followed by extensive opportunity to interact with peers results in rapid adjustment and leaves no obvious deficits (Harlow and Harlow 1969:35). Six months of isolation results in a marked degree of social debilitation, and a twelve-month isolation period has devastating effects with no hope for reversal. Harlow has briefly summed up the effects of isolation as: (a, inadequate social and even nonsocial play, (b. avoidance of physical contact, (c. absence of normal heterosexual behavior, and (d. inability to inhibit antisocial aggression when the animal is not too terrified to aggress (Harlow and Harlow 1969:35).

It was pointed out earlier that monkeys raised in subtotal isolation were permitted visual and auditory access to other infants but were denied maternal and age-mate affection. While this form of isolation produces little or 178 no apparent intellectual deficit (Suomi, Harlow and Kimball

1971:1171) the social debilitation, particularly during the first year of life, is very evident. Harlow conducted a study of subtotal isolates by using forty-eight rhesus monkeys— half male and half female, ranging in age from two months to thirteen and one-half years. He included twelve feral controls— six male and six female--in the survey.

The results indicated that numerous behavioral differences were associated with age and sex variables, and also that most of the isolates ' behavioral levels declined with increasing age, males consistently exhibiting more disturbance activity, more threats and less grooming than females (Suomi, Kimball and Harlow 1971:1174). Partial isolates 10 to 13ig years of age exhibited few behavior patterns in their home cages other than passive staring, in marked contrast to the wide range and high incidence of bizzare disturbance activity previously reported for younger partial isolates (Harlow, Schiltz and Harlow 1968:185).

The severity of the affliction that grips monkeys raised in the partial isolation of individual wire cages becomes more apparent as they grow older. They pay little or no attention to animals in neighboring cages,* those caged with companions usually sit in opposite corners with only rare interaction. No heterosexual behavior has ever been observed between male and female cage-mates, not even between those that have lived together for as long as seven 179 years (Harlow and Harlow 1962:139), Trying to mate these isolates has proved even more futile— when animals were paired during the female's estrus, they often fought so viciously that they had to be parted. In rhesus monkeys copulation is possible only with the male standing on the

female’s ankles, so that coordination is necessary in both partners. Even experienced animals were for the most part unable to induce uncoordinated sexual behavior in the inexperienced partner. On the other hand, monkeys that had had the experience of playing with other young monkeys for a few weeks were able to function normally as adults (Scott

1972:157).

Scott goes further to point out that when mating was

finally achieved with some of the isolated females, they manifested gross shortcomings in maternal behavior when

their offspring were born. "Instead of constantly holding an infant in her arms, a mother reared as an isolate would neglect it, step on it, or even strike it when it called."

(Scott 1972:157). Often the maternal behavior pattern

improved considerably after the second pregnancy. This

study indicates that the organization of sexual and maternal behavior is dependent upon experience gained after birth,

and also that coordination and efficiency of these behaviors

improves with adult experience (Scott 1972:157).

Having discussed the effects of isolation (both

total and subtotal) on rhesus monkeys, we might take a brief moment to compare the behavior of these laboratory-born 180

animals with a group of rhesus monkeys that had been

captured in the wild during their first year of life and housed in captivity for a while before being individually housed in the laboratory. The most noticeable difference between the two were in their sex and social behavior. All

the animals born in the wild— and not one laboratory-born

animal— displayed normal sex behavior (Harlow and Harlow

1962:139). The normal sex drive was not absent from the

laboratory-born animals who often displayed patterns of

sexual presentation, but they did not offer themselves

correctly and were unable to mate successfully. Don G. Davis

(1962:73) has pointed out that under conditions of captivity

certain animals develop a psychosis which hinders mating and

reproduction. When females are in estrus, males appear

physically incapable of mating. He attributes this

situation to a "lack of knowledge" of the mating technique,

a very real problem characteristic of most primates, great

apes in particular. His observation of orangutans and

gorillas indicated that the breeding procedure is not an

inherent characteristic and that young animals learn partly

through observation or from the participation in the sexual

play which takes place within their social group (Davis

1962:73).

Primates that have been in captivity since birth show

a marked absence of normal social behavior by fighting and

not engaging in social grooming. On the contrary, captive

monkeys born in the wild had learned to live with each other 181 in a stable hierarchy of dominance or "pecking order"

(Harlow and Harlow 1962:139), rarely fought and engaged often in social grooming. In social testing, they would also release a companion from a locked cage more frequently than did the laboratory-born animals, who usually ignored a caged partner's plight (Harlow and Harlow 1962:139).

While isolation of any degree or duration impairs the behavior pattern of a primate, research indicates that six months of isolation will render an animal permanently inadequate (Harlow and Harlow 1962:141). On the other hand,

Harlow feels there is reason to believe that the effects of shorter periods of early isolation (perhaps 60-90 days or even more) are clearly reversible. Therefore, it is clear that denial of both maternal and age-mate affection during the first six months to one year of life produces a syndrome of persisting social and sexual ineptitude and abnormal aggression in monkeys, even though in some animals the appearance of aggression is much delayed (Harlow and Harlow

19 69:19). This then is the critical period in which social deprivation may result in effects which are irreversible.

As mentioned earlier, the effects of isolation have been clinically tested only on rhesus monkeys and, to a very limited extent, chimpanzees. While both availability and cost have prohibited experimentation with orangutans and gorillas, there is evidence indicating that isolation would have much the same effect on them. 182

Although most primates are characterized as very social animals, wild orangutans appear to be individualistic and solitary. When observed in their natural habitat, one generally encounters independent animals either solitary or accompanied by their dependent young (Galdikas-Brindamour

1975:446). It is, undoubtedly, the least gregarious of the apes, and in maturity, tends to seek isolation. The family, a female and her offspring, make up the social unit of orangutan life. MacKinnon (1974:13) uses the term "sub­ group" to describe those animals moving about as one unit.

Although males occasionally consorted a female, 80% of the sub-groups were made up of one animal. Most of the remaining sub-groups were made up of two animals. No sub­ group had more than five animals- Except during the mating season, male orangutans live alone and are not very sociable creatures (Yerkes and Yerkes 1929:136). Despite the fact that the orangutan is, by nature, a solitary primate, isolation in captivity may have devastating effects. As

Dr. Yerkes points out, "to keep an orangutan in complete isolation from others of its kind, and other organisms, and without even occasional human companionship for play and exercise, is likely to prove unfavorable to adaptation in

captivity (Yerkes and Yerkes 1929:134).

While it was originally believed that the gorilla was not a very gregarious animal (Du Chaillu 1861:349),

later studies indicated that apart from "solitary hypocondriacs" (von Koppen 1887:418) the gregariousness of 183 the gorilla implied a measure of sociability, but the habits and habitat of the animal render prolonged observation of social relations extremely difficult (Yerkes and Yerkes 1929:435). It is also difficult to assess the attitude of the wild gorilla toward man, and even more difficult to determine this attitude in captivity for it often varies in accordance with sex, age and previous experience. Yerkes points out that the younger the specimen the more likely it is to adapt easily and to become attached to and dependent upon its human caretaker. If brought into captivity as late as five years of age, there may be persistent resentment of human approach and constant hostility. This seems much more likely to occur in the male

than in the female. Although the descriptive terms

"hostile," "morose," "sullen" and "unsociable" are

contradicted by the behavior of certain individuals, they

seem applicable enough when an attempt is made to contrast

captive gorillas with chimpanzees or man (Yerkes and Yerkes

1929:440). Groves (1970:56) has emphasized that

companionship is a very important aspect of ape care as

gorillas are social animals and, like man, become

introverted if forced to live alone. He suggests that a

very young animal should be given a foster mother, when it

is a little older it needs a playmate. If there is no young

gorilla of comparable age, then a chimpanzee should be given

as a companion. The author goes on to suggest that a young 184 gorilla without adequate playmates with whom he can learn to cooperate and who will "give as good as they get," becomes like the spoiled "only child" in a human situation

(Groves 1970:64). George B. Schaller (1964:231) has referred to the isolation of gorillas in zoos as

"scandalous," and has categorically stated that young apes need the same kind and amount of attention given human infants.

With assurance it may be stated that the chimpanzee is a sociable creature which lives in family groups or small bands and which only exceptionally, aside from senility and ostracism, lives in solitude. Recent studies have revealed that chimpanzees not only enjoy a social relationship and share food with each other but actually cooperate in hunting activities which involves joint participation in the chase and sharing of the prey (Teleki 1973a). In fact, the chimpanzee appears to be adverse to solitude (Garner

1896:54-60). Jane Van Lawick Goodall has compared the chimpanzee in a zoo to a human being who has been in prison for several years and has no hope of release. She indicates that the isolated zoo chimpanzee "has none of the calm dignity, the serenity of gaze or the purposeful

individuality of his wild counterpart" (Goodall 1971:258).

Yerkes disputes this (1929:250) and claims instead that

although removal from the normal social environment profoundly modifies the life of the organism, this does not

necessarily interfere with the animal's psychophysical 185 growth or development. However, social stimuli play a significant role in the development of the chimpanzee and isolation can significantly alter the behavior patterns.

In isolated and lonesome individuals the self image (mirror image) commands attention and arouses interest — any novel object is treated as if it were a fellow being.

Retrospectively, Melati and Mewar exhibited some of these same classical behavior patterns of isolated primates.

The twins actually went through two separate stages of isolation. The first stage was the planned stage in the nursery when it was decided to withdraw as much human emotional support and only supply physical aid. The second stage was when the infants were separated from each other in the House of Small Mammals. Melati then went through a third stage of isolation when Mewar died and undoubtedly a fourth when she was shipped out of her familiar surroundings to another zoo.

During the nursery period, aside from the developmental plateaus that stemmed from lack of stimulation, several behavioral characteristics paralleling

Harlow's rhesus behavior patterns became apparent. Non nutritional orality in the form of the persistent sucking each infant inflicted on the other was coupled with systematic aggressive behavior. This type of behavior is characteristic of 6 month isolates rather than 3 month isolates. According to the studies previously mentioned, these behavior patterns and other aberrant behavior patterns 186 are reversible if, after 6 months, a primate can be placed with normal peers and other normal animals of its species.

In the cage situation, after Melati and Mewar were separated and later reunited, social indifference was exhibited. This was a characteristic exhibited by isolated monkeys and chimpanzees. The twins did sit in opposite corners, just as Harlow's isolated monkeys did, with little or no interaction. Since this period of time was marked by the twins showing little interest in each other and no attention to animals in neighboring cages, it is possible that Melati would have learned little from her mother in the adjacent cage or from observing the courtship play between Atj eh and his intended mate.

Absence of social grooming was noted but it is unknown how much orangutans groom. Grooming has never been reported of orangutans in the wild. Chimpanzees rarely groom but have been known to groom their infants somewhat.

Absence of this type of behavior would not indicate anything significant at this time.

One of the isolated behavior patterns was exhibited by Jennie when she was nervous over her new infant and that was compulsive self mutilation. Jennie repeatedly gnawed at one spot on her wrist until much of the flesh was exposed and the area bled continuously. 187

MATERNAL DEPRIVATION

The effects of maternal deprivation manifest themselves in three broad categories of abnormal behavior-- social, sexual and maternal. Outlasting any other social bond, the nonhuman primate mother-infant relationship is very intense in terms of time, energy and effect (Hamburg

1969:8). Emphasizing this attachment behavior, John Bowlby points out that at birth, or soon after, all primate infants cling to their mothers. During early childhood, mother and infant remain in close physical contact which gradually diminishes over the years (Bowlby 1969:184). It has been observed that an infant primate may be profoundly disturbed by a period of separation from its mother, and several researchers have conducted detailed experiments to determine the effects of maternal deprivation during infancy. In recent years there have been numerous studies of the effects of a wide variety of mother-infant rearing relationships on the social development of rhesus monkeys.

When a monkey mother and her infant are separated, it becomes an extremely stressful event for both mother and infant as well as for all other monkeys related to that experience. In order to study the effects more closely, researchers have varied the nature and duration of the separation ranging from six days to as long as four weeks

(Bowlby 1973:62). 188

Kaufman and Rosenblum (1967) studied the behavioral effects on infants separated from their mothers for four weeks and learned that all infants reacted initially with agitation followed by severe depression lasting approximately one week. This behavior resembled the

"anaclitic depression" of human infants who had lost their mothers. During the month of separation all animals studied showed a significant decrease in play, both social and nonsocial, and a marked increase in self-directed behavior.

When the mother was reintroduced, there was a tremendous reassertion of the dyadic relationship with marked increase in clinging and nipple contact (Kaufman and Rosenblum

1967:1030-1031) . The infants showed intense tantrums when rejected and often flung themselves violently on their mothers, or sometimes, when mothers had rejected them, on to aunts. Another striking feature found during the early weeks of reunion was a change in which relaxed infants became upset and clinging without apparent cause.

Subsequently, they were less willing to approach an experimenter offering food, stayed closer to their mothers when moved to a strange cage, made shorter visits to a cage containing strange objects and were less active after having been frightened by a minor happening (Spencer-Booth and

Hinde (1968:68).

Spencer-Booth and Hinde (1971:174) conducted experiments to determine the effects of six days of maternal deprivation on rhesus monkeys eighteen to thirty-two weeks 189 of age. Assessing the mother-infant relationship quantitatively, they found that during separation activity

and play decreased. When the mother returned, the infant was more clinging than before the separation. Moreover,

some of the effects of separation were still apparent four weeks later. Infants separated for the second time

responded similarly to infants separated for the first time

at the same age. While allowing for a considerable degree

of individual variation, the impact of a second separation

can be generally assessed in terms of its short-term and

long-term effects. When the behavior of infants separated

for the second time was compared to that of infants of the

same age separated for the first time, no differences were

apparent during the separation itself or during the month

that followed. However, it would be incorrect to imply that

the effects of two separations are no different from the

effects of one. The long-term effects of two separations

indicate that separated infants continue to show some

persistence of those symptoms of depression and of disturbed mother-infant relations which had been conspicuous in the

month immediately following the mothers' return. Separated

infants also demonstrated very strained behavior while in a

strange environment. The differences between the separated

monkeys and the controls were much less marked at thirty

months than at twelve months, but there was a noticeable

pattern. The most significant differences were between the

controls and the twice-separated infants, with the 190

once-separated infants occupying an intermediate position

(Bowlby 1973:70). The findings further indicated that the

effects of a separation are proportionate to its length— two

six-day separations are worse than a single six-day

separation.

At this point it might be feasible to emphasize some of the individual variations of response to separation. Age

difference has little effect in determining the nature of

the response, but sex difference does seem to account for

some variation. Males appear to be more affected than

females, both during separation and after it. Spencer-Booth

and Hinde (19 71) indicate that male infants tend to cling to

their mothers more than female infants in the early weeks

and less after the first thirty weeks. Male infants also

receive a higher proportion of rejections and play a bigger

role in maintaining proximity than females (Spencer-Booth

and Hinde 1971:183). The most remarkable observation,

however, was the correlation between degree of distress

shown by an infant and certain features of the mother-infant

relationship (Hinde and Spencer-Booth 1967). Those infants

most frequently rejected by their mothers are the ones most

distressed during the first month after separation. While

the degree of distress is correlated to the degree of

rejection before and after separation, it has been noted

that maternal rejection before separation has a deleterious

effect. These correlations do not indicate that the quality

of the mother-infant relationship inevitably determines the 191 difference in an infant's responses to separation but it is likely that it often does. It was also noted that infants permitted to live in familiar surroundings after separation from their mothers are less disturbed than those who endure the period of separation in an alien environment. It would be pertinent to point out that, just like the infants, mothers who remain in familiar surroundings are less distressed by the absence of their infants than those mothers who are removed. As a direct consequence of this, they behave more maternally and reject less after the reunion, fostering a more harmonious reaction between the infant and the mother. This substantiates the theory that a mother's reaction influences the effect that separation has on the infant (Bowlby 1973:73-74) .

In order to accurately estimate the effects of maternal deprivation, several researchers have compared and contrasted the behavior of rhesus monkeys raised by their normal mothers with those raised on cloth mother surrogates.

When a wire and a cloth surrogate was provided, infants developed a strong attachment to the cloth mothers and little or none to the wire mothers, regardless of which one provided the milk. In fight-inducing situations, the infants showed that they derived a strong sense of security from their cloth mothers, and even after two years of separation, they showed persistent attachment to the effigies (Harlow and

Harlow 1962:140). 192

In their study of monkeys raised only with peers,

Chamove, Rosenblum and Harlow (1969:28) state that the normal mother adequately provides the stimuli for the first affectional system and an inanimate mother surrogate could not. Therefore, animals raised on cloth surrogates accept this object as a source of maternal comfort and security but they cannot receive any form of maternal social interaction, including early maternal restraint or later maternal rejection. Cloth surrogates are substandard in that they are devoid of facial, vocal and gestural language. They cannot protect or punish their infants and cannot respond reciprocally to their infants' behavior.

Infants raised by these mothers become socially and sexually aberrant. However, when compared to a monkey raised in a cage with only a cloth diaper pad for comfort, the surrogate-raised animals seem to be less aggressive toward themselves and other monkeys (Harlow and Harlow 19 62:140).

An interesting experiment conducted by Rosenblum in

1961 indicated that monkeys raised on cloth surrogates, but not deprived of peers developed exploratory behavior followed by social play and exhibited highly complex interactions as well as appropriate sexual behavior. By appropriate, he meant that meaningful sexual advances were made to the right sex and mounting was attempted.

Satisfactory patterns of rough and tumble and approach- withdrawal play also developed early in life. Ernst W.

Hansen (1966) conducted a similar experiment in a playpen 193 environment with rhesus monkeys but used a set of controls for comparison. The results indicated that with reference to rough and tumble and approach-withdrawal play, mother-raised babies with access to peers were in advance of surrogate-raised babies with peers, but the differences lessened with time, and by the end of the first year the two groups were similar (Harlow and Harlow 1969:30). While the social behavior of the two groups was the same, the sexual behavior of the surrogate-raised monkeys was not normal although appropriate. All in all the results suggested that live mothers impart a social advantage to their offspring in the first six months of life but this is in part negated in the second six months when the mother-raised infants are subjected to maternal ambivalence.

Surrogate mothers, on the other hand, are constant in their stimulus values (Harlow and Harlow 1969:31).

Another aspect of maternal deprivation can be assessed by studying the behavior of rhesus monkeys removed from their mothers soon after birth but raised in the company of peers. A high frequency and persistence of social clinging response is manifested, indicating that the primary variable binding the infant to its mother is physical contact. Allowing two newborn infants to continuously interact with only each other produces socially abnormal monkeys that develop what has been called the "together- together syndrome" (Chamove 1974:48). This syndrome is characterized by an excessive amount of socially directed 194

clinging behavior and greatly reduced social play during

the first fifteen months of life. Basic cling patterns are

dor so-ventral and ventro-ventral. While the latter form of

clinging is more prevalent in the early months, the

dorso-ventral form becomes more noticeable in the later

months. Research indicates that together-together infants

remain significantly below mother-raised groups in contact play and sexual initiation {Chamove, Rosenblum and Harlow

1973:323). The clinging response inevitably inhibits the

development of normal peer social interaction. The

frequency and intensity of the clinging is thought to be

attributed to the absence of the tendency of a mother to

begin to reject the clinging attention of the infant

starting at about three months of age (Chamove 1973:48).

The negative responses of the mother assist the infant in

gradually breaking its dependency relationship to her, a

necessary step in the socialization process (Harlow 1966).

The results seem to indicate that developing in the presence

of peers cannot substitute for maternal rearing. Despite

the companionship provided, the socialization process is

inhibited, leading to further social and sexual

abnormalities.

Maternal deprivation of infant monkeys also has some

long-range effects. Females suffer from an abberation of

maternal behavior ranging from indifference to abuse (Harlow

and Harlow 1962:142). When the neonate monkeys are too

young to make contact, the "unmothered mothers" ignore them 195 but when the infants grow large enough to actually struggle

to make contact, there is a high increase in the number of punishment responses. Sometimes the mothers beat the

infants for no apparent reason (Harlow 1963:26). This

abusive behavior, in turn, fosters maladjustment and

aggressiveness in the infants, thus continuing the vicious

circle. Observations indicate that from an early stage an

infant shows a tendency to imitate its mother. This

response to another monkey's behavior carries over into peer

interaction. It is apparent, also, that sexual activity is

stimulated by the mother's grooming of the infant. Finally,

as the mother begins occasionally to reject her offspring in

the third or fourth month, the infant is propelled into

closer relations with his peers. These observations underlie

the fact that the mother-infant relationship plays a positive

role in the normal development of the infant-infant and

heterosexual relations of the young monkey (Harlow and

Harlow 1962:142).

That stress occurs during maternal deprivation has

not been studied merely on a social behavior plane. There

are laboratory tests of chemicals in the blood and urine that

verify some of the social behavior findings. Yerkes Primate

Center has had experience in hand-rearing apes in captivity

for over half a century. To assure a 100% certainty of

keeping infant apes alive, all infants are taken from their

mothers shortly after birth and hand-reared (Yerkes and

Yerkes 1929; Bourne 1974). Secretions of chemical compounds. 196 hydroxysteroids, are found in the bloodstream and urine of both mother and infant after such a separation. In the mother, the hydroxysteroid level falls to normal within a few days but persists much longer in the baby. At Yerkes, these tests are widely used to test all possible indications of stress under different circumstances as well as the amount and duration of stress.

Although it would seem that the literature is rich in studies involving social adjustment of primates, it must be remembered that there are several hundred species of living primates but reliable field studies of approximately twenty. Laboratory studies have not used many species either and only great ape members have been subject to systematic long-term observation under natural conditions.

Studies of primates in the wild take years to develop a reliable picture of social stability and how certain species cope with activities of daily living. At the end of four years Jane Goodall had spent approximately four thousand hours in the field and only in the fourth year was able to report on the critical issues that have given us striking insight into chimpanzee life. She has been able to observe some cases that qualify as maternal rejection and maternal deprivation as it occurs under natural circumstances. As yet, we have no such information on gorillas, gibbons or orangutans in their natural habitat over a long-term period of time. 197

Goodall (1971) writes of a case in which an infant chimpanzee had been adopted by an older, though still immature, sibling after the loss of its mother. The orphan was one year old and still dependent on maternal care for milk, transportation and food. A six-year old male sibling attempted the total care of the infant, cuddling her, grooming her, transporting her and feeding her bananas. In spite of his devotion and good intentions, the infant died two weeks later. It is not known if the cause of death was related to physical or social circumstances. Solid foods do not play an important role in the diet of an infant chimpanzee until it is over two years of age although hand-reared infants in captivity are eating solids considerably before then. An earlier study (1967a) of an observed sibling adoption had similar results indicating that, even with persistent effort, immature siblings cannot provide adequate care even though they are somewhat experienced.

Goodall reports a case of an aged chimpanzee mother no longer strong enough to cope with her active son (1971) .

She rejected him at an early age in life, thus creating a prolonged childhood and making him a disturbed juvenile.

The mother, F lor, no longer had the strength to discipline her five-year old son, Flint. When she refused suckling

him, Flint would hit and bite her until she eventually gave

in and allowed him to nurse. Though aging, she became

pregnant again and her milk supply diminished through the 198

natural hormonal changes of pregnancy. Deprived of his

comfort, Flint began to constantly cling to Flo, whimpering when she went a few yards, interfering when she groomed

another of her offspring and crying for attention. When

Goodall lost sight of Flint, he was six years old and

competing with Flo's new infant for nursing time, food

sharing and insisted on ventral and dorsal riding as well as

sharing her night time nest. He had grown listless,

lethargic, declined invitations to play and spent longer

periods of time grooming.

When Melati and Mewar were separated from their

mother, no separation anxiety was noted. Infant apes and

infant humans are very much alike in the neonate period in

that they are much more maternal-dependent and physically

unresponsive than infant monkeys. An infant monkey is

developed enough to show facial, physical and vocal

reactions to new stimuli as soon as it is introduced to

environmental or emotional fluctuations during the neonate

period. The ape or human infant sleeps for long periods of

time and wakes for feeding purposes. It is difficult to

know what data is registered in the psyche when the

environment is unstable. Some human infants develop feeding

problems or failure to thrive shortly after birth. These

problems are usually attributed to anxieties suffered by the

neonate in relation to the emotional state of his mother or

physiological problems in the infant's digestive tract.

Most human infants in our own culture are separated from 199 their mothers immediately after birth if they are born in a hospital. After approximately 24 hours or longer they are given to the mother for feeding purposes only if it appears that the infant is strong and healthy enough and the mother does not have a cold, fever, or some condition that might be harmful to the neonate. The average length of stay for a human infant in a newborn nursery is 3 days (CPHA 197 5:118) although some healthy infants may remain there for a week or

10 days if the mother has had a difficult delivery, an elevated body temperature or has had a caesarean section.

Even if the infant is allowed to room in with the mother in the hospital, she is not allowed to keep it in her bed at all times and only if she is breast feeding is there ever skin to skin contact between mother and infant. Blood steroid levels are not drawn on human infants to ascertain any anxiety present in newborns separated from their mothers at birth. When comparing the reactions of Melati and Mewar to the reactions of newborn human infants, there seemed to be no difference except that human infants are given pacifiers or offered bottles of water when they need sucking satisfaction. As with human separations, no blood was drawn to determine the amount of stress involved in the separation.

Although no early patterns developed to show the twins were suffering from maternal deprivation anxieties, patterns did become apparent which duplicated some of the deprivation patterns noted in the classical studies conducted by the Harlows and their co-workers. As 200 previously mentioned, mother-raised babies were noted to be in advance of laboratory raised babies. This observation became a reality for the twins during the second and third month when it was discovered that the twins were not progressing at all due to lack of maternal stimulation and lack of physical opportunities. This pattern persisted in many aspects because the proper exercise equipment was not substituted for exercise advantages the infants would have had from normal maternal clinging and swinging opportunities. The high frequency of social clinging exhibited by the twins resembles Chamove's "together together" syndrome exhibited by monkeys removed from their mother after birth and raised in the company of peers.

After the second period of separation in the cage, although the twins were separated from each other rather than a mother, their behavior resembled that of maternally deprived monkeys after brief separations. Kaufman and Rosenblum

(1967) described marked increase in clinging and intense tantrums upon réintroduction of mothers after a four week separation. This is exactly how Melati and Mewar behaved around their keepers and attendants during feeding periods after the partition was built in the cage. 201

DISEASE IN CAPTIVITY AND ITS EFFECTS ON BEHAVIOR

Malnutrition is perhaps the most widespread affliction endured by captive animals since a nutritious and balanced diet is an aid to disease control. It usually appears soon after introduction to captivity when young animals have difficulty adjusting to a new diet. The dietary changes often cause diarrhea, further aggravating the condition related to malnutrition. Despite efforts to provide adequate food, captive animals often receive an unbalanced and nutritionally poor diet which inhibits resistance to common parasites and other agents of disease.

Nutritional deficiencies have an immense impact on the behavior of animals often inducing lethargy, gastrointestinal problems and general apathy. More important, malnutrition lowers the resistance level of animals who are exposed to such communicable diseases as tuberculosis, pneumonia and internal parasites. In order to avert the problems caused by deficient diets, zoo biologists have gone to the extreme of providing scientific balance in the form of ration cakes.

Herbert L. Ratcliffe, a pioneer in the field of scientific food formulas for captive animals, has presented valuable statistics indicating the decrease in deaths per year following the change in diets at the Philadelphia Zoo.

For instance, effective levels of resistance to dysentery bacilli developed within about eight weeks after improving 202 the quality and quantity of dietary protein for primates

(Ratcliffe 1966:6). A similar change to scientifically planned diets was made by the Basle Zoo in Switzerland.

Hans Wackernagel, the scientific assistant at the zoo, claims that it resulted in better health as well as repeated success in breeding animals (1966:34). Both follow the

"retort theory (Retorten-Auffassung)," maintaining that the digestive system of a wild animal is such that one has only to feed it carefully balanced amounts of protein, carbohydrate, fat, vitamins, mineral and trace elements for the progress of nutrition to keep the animal healthy

(Hediger 1966:37). H. Hediger violently disagrees with this approach to feeding captive animals. He insists that every care must be taken to preserve zoo animals from the effects of domestication and provide them with living conditions as close to nature as possible (Hediger 1966:38). Hediger emphasizes that the food of animals must be natural and points out that presenting captive animals with scientifically prepared cakes, biscuits and pellets can have ill effects.

The rapid increase of arteriosclerosis among captive animals is often attributed to controlled diets.

Even Ratcliffe and Cronin (both advocates of scientifically controlled diets) concede that arteriosclerosis was remarkably rare before the diet reforms. Since 1935 when

traditional but often inadequate zoo diets were replaced by

controlled diets, arteriosclerosis has developed much more 203 frequently (Ratcliffe and Cronin 1958:41-52). The complete-ration diet often eliminates the proper use of the jaw muscle, teeth and claws, causing their atrophy.

Repetitive daily diets do not cater to the fluctuating appetities of most free-living animals, who, in captivity, are deprived of selecting temporarily favored food and the lack of variety can induce monotony and often results in erratic or repetitive behavioral patterns of a pathological nature. Yet another adverse effect of the scientific diet

(but one that manifests itself psychologically rather than biologically) is the elimination of the animal-man relationship. The introduction of the daily ration reduces the number of feeds which, in turn, minimizes the contact between man and animals. This has a particularly devastating effect on anthropoid apes who need intensive contact with man (Ratcliffe 1966:49). Hediger (1966:49) states that the major focus of a wild animal's activity is to procure food and when captive animals suddenly find themselves divested of this driving force, they are left with a considerable amount of unreleased energy. This is one of the ill effects inherent in a system of presenting food to an animal on a daily basis and eliminating the natural search and procurement of food which forms an essential part of an animal's life in the wild. If this energy is not rechanneled, it affects natural behavior and results in a number of stereotyped movements commonly observed in zoo animals. 204

Captive animals suffer from diseases that are a direct result of some vital dietary deficiencies. Ascorbic acid deficiency can lead to a form of scurvy, causing bleeding gums, loss of teeth and weakness of extremities.

The animals often end up pulling out much of their hair.

Cousins (1972:212) indicates that this behavior results from skin irritation which accompanies the other symptons and may actually be caused by bacteria.

Vitamin A deficiency hinders the normal development of animals and prevents the rapid healing of wounds; it also has an adverse effect on teeth and gums. Often the pathological condition of the animal obstructs the proper absorption and storage of Vitamin A, precipitating these symptoms and leading to the formation of lesions in a more advanced stage. Potassium deficiencies can be caused by chronic gastrointestinal disturbances so common in captive animals. This causes general weakness and often exposes the animals to conditions of tension and stress.

Dental problems are also associated with dietary deficiency. While zoo cakes provide all the required nutrients, the absence of tough fibrous plants often has an adverse effect, permitting the teeth of captive animals to grow too long. In some cases the diet also hastens the development of dental caries, particularly in older animals.

Rickets and Osteomalacia, often inaccurately called

"cage paralysis" are two diseases common to captive animals.

Factors which lower the concentration or availability of 205

serum calcium and/or phosphorus may effectively oppose

deposition of bone salts in the organic matrices of

cartilage and bone and thus result in rickets or osteomalacia. Rickets is essentially a disease of early

life and the external symptoms are a large head, a squatty

station, heavy extremities and a prominent belly. Recovery

is occasional and the animal usually retains the distortion of its skeleton. Osteomalacia, on the other hand, appears

in mature animals, and the first symptoms are noticeable

lethargy and inactivity followed by alterations in the shape

of the chest and legs; this disease is usually fatal.

Another problem that often afflicts captive animals

is the retardation in the onset of ossification. Research

conducted on chimpanzees indicated that various

environmental and physiological factors are responsible for

this (Nissen and Riesen 1949b:665). This retardation in the

onset of ossification of epiphyses and short bones of the

extremities was found to be associated with several deviant

conditions such as— rearing of the infant by its own mother

in captivity, general constitutional inferiority, early

castration in the male, light deprivation for a long period

during infancy, restriction of tactual experience and

opportunity to grasp and nutritional deficiency (Nissen and

Riesen 1949b:674).

In recent years there has been an effort toward

developing diets at reasonable costs. These efforts aim for

diets that are readily acceptable, prevent nutritional 206 disease and allow animals to develop and maintain high levels of resistance to many of the common agents of disease. The current trend in nutrition is to effect a balance between a scientific diet and natural foods and to adjust this diet to the needs and vagaries of individual animals.

Environmental factors play a large role in determining responses to medical, social and reproductive problems. The most obvious forces of a captive environment are climate, food and intraspecific or social relationships (Ratcliffe 1966b;207). Often the social environment can work toward impairing the behavior patterns of a captive animal. While security may exist in a zoo, most animals there have been captured as infants, precluding satisfactory parental and peer relationships during the periods crucial for normal psychological development. Often the drastic nature of the environmental upheaval has an important effect on future behavior and possibly on morbidity and mortality (Stout, Ogilvie and Lemmon 1969:197).

Well documented evidence indicates that an unsatisfactory social environment may result in activation of latent infections, susceptibility to mould diseases, decreased fertility, reduced growth potential of young and increased frequency of at least two forms of organic disease

(Ratcliffe 1966b : 208).

One of the most difficult problems to deal with in a zoo is Coprophagy, the eating of excrement, in the ape 207 collection. It creates feelings of disgust and embarrassment in the public, and is very difficult to cure

(Hill 1966:251). It must be pointed out that coprophagy is typically a behavior pattern of captivity and is often thought to result from monotony and boredom. Some zoos have reported that when apes were deprived of their outdoor activities in the winter they resorted to coprophagy— first by drinking their urine and then by eating their feces.

Other zoos attributed the disease to abnormal body processes and deficiencies in diet. Punishment sometimes helps but play therapy seems to be most helpful in reducing the habit.

A change of cage mates and increased intake of sodium chloride seem to help. If the practice is detected in its early stages it is much easier to handle.

Another habit that is common to captive animals and absent in their wild counterparts is regurgitation. It is felt that extreme boredom coupled with restricted living space, where the animal can find little else to do but eat, is responsible for this unattractive behavior (Cousins

1972:215).

The correlation of behavior and pathology in zoo animals has received intensive investigative study in recent years. The Institute for Comparative Pathology performs post-mortem examinations on most of the nonhuman primates that die in Dr. W. B. Lemmon's colony (Stout, Ogilvie and

Lemmons 1969:198). Here the animals are kept in stable groups and are mainly used in studies of psychosocial 208 development. Pathological studies in this situation have been particularly valuable because of the precise records kept on each animal during life. This makes it possible to conduct a study in which an attempt will be made to correlate evidence of abnormal behavior with mortality and with pathologic findings at autopsy.

It is difficult to analyze the health problems suffered by the orangutan twins. The psychological trials, unfamiliar surroundings, changing feeding patterns, changing food content, presence of cockroaches and rodents or some undiscovered internal disease may all have played a part in the persistent diarrhea and abnormal liver studies or it may have stemmed from just one cause. Not enough tests were done as the twins were developing to note changes in cell patterns or enzymes. No liver function tests were done until the infants were truly ill and it may have been that the liver function tests were abnormal from birth. When

Mewar died, no autopsy was performed because she did not die from an illness but from an accident. Since twins are so much alike, however, an autopsy might have been helpful in determining the health status of the remaining twin. There will always be a gap in the medical history of Melati and

Mewar because their health status was a secondary factor, not under study and not considered until out of control.

They lacked both preventive and maintenance assistance in terms of both dietary planning and medical management and received attention only after establishment of a problem. 209

LEARNING SKILLS OF GREAT APES

Among humans innate behavior patterns are more prominent in infants while learned behavior governs adults.

Riopelle states that theoretically, the more complex the nervous system, the less a creature tends to depend on inborn actions and the more dependent it becomes on learning

(Riopelle 1972:362). This theory has led researchers to conduct extensive studies on primates to determine the degree of their problem-solving intelligence.

There has been a general tendency to establish a positive relationship between cranial capacity and intelligence. While the learning skills of the primates are not to be accounted for solely in terms of volume of the neocortex relative to total brain volume, it is of significance that in the primate the neocortex is proportionately greater and accommodates greater fissuration than it does in carnivores and rodents. The highly developed primate capacity to synthesize "complex systems of external stimuli" has been attributed to their highly developed neural capacities (Voronin 1962:187).

Some of the most significant experiments on learning skill analysis of great apes were those performed by

Wolfgang Kohler to determine the existence of insightful behavior in primates. He was interested in determining the kind of problem-solving skills that might be provided for by the chimpanzee's advanced brain structure. Moreover, he was 210 convinced that it was totally reasonable to call certain highly-adaptive plastic type behaviors insightful and intelligent, while others devoid of these characteristics and more of the association type be labelled as unintelligent. By this, Kohler demonstrated the shortcomings of the Thorndikian theory which does not account for "intelligent" behavior (Rumbaugh 1970:11), He emphasized that animals should be tested in tasks of graded difficulty so as to avoid unnecessary stress and agitation.

However, he failed to emphasize that experience is an important factor in primate ability to solve problems but this should not be taken to mean that he did not realize this crucial fact, Kohler also advocated that in order to assess the true measure of insightful learning, the subject must have perceptual access to all the important elements of the situation. He further emphasized that the incentive should be attractive enough to sustain the subjects attention. He did not rule out the effect that chance happenings might have on an animal's attempted solutions and also conceded that habits formed during the experiments might facilitate or interfere with the appearances of insightful, intelligent behavior. Kohler evaluated several examples of insight (chimpanzees joining two tubes to get one of the required length or stacking boxes on each other in order to reach an overhead incentive) and came up with an exciting idea. There seems to be in apes a high positive correlation between intelligence and dexterity (Kohler 211

1925:176). This insightful or ideational theory has been challenged by several authorities (primarily Spence) but the dispute remains one largely of semantics in which empirical results have failed to convert either side. One aspect of the insightful theory was that the transposition phenomenon constituted strong evidence for the operation of relational processes. The experiments conducted indicated that the subject did not simply learn a specific response to a specific stimulus, but that it learned a relation. This

supported the operation of a relational process in the chimpanzee as opposed to just the operation of excitatory and inhibitory behavior among an aggregation of stimulus

components (Rumbaugh 1970:16). Kohler's theory of

insightful learning was further substantiated by Harlow's

formulation of Learning Sets (LS) which clearly indicated

that experience was critical for the appearance of so-called

insightful behaviors (Harlow 1949:51-65).

Experiments indicate that great apes are not

necessarily efficient learners but, as Jarvis (1966) points

out, spatial and temporal proximity of cue to reward often

plays a critical role in determining the speed with which

visual discrimination can be made. It has also been

observed that reward contributes more to learning of

discrimination problems than does nonreward (Thompson

1954:134). By the same token, a positive stimulus serves as

a more effective cue than a negative one for the

determination of the discrimination response. 212

Some of the measures by which the learning skills of great apes are determined are by the use of multiple cues, picture memory and object identification. While Nissen,

Blum and Blum (1949) suggested that primates were capable of considering a large number of cues before determining a correct choice, Farrer (1967) disputed this theory and pointed out that the chimpanzee had learned each of the stimulus configurations independently during several experiments. However, Farrer's theory does not necessarily suggest that chimpanzees cannot make choices contingent upon the processing of several independent cues. The two studies suggest that some chimpanzees do have the capacity of recognizing considerable numbers of stimulus configurations even though they share many elements or stimulus characteristics (Rumbaugh 1970:24).

In a set of experiments designed to test the picture memory of chimpanzees Farrer found that a match-to-sample task (without the presence of the sample) was performed successfully, but if part of the stimulus was eliminated there was a decrease in performance which was further disrupted by the loss of rewarded stimuli. The mirror image of the original pictures were, however, treated as new pictures to be memorized (Farrer 1967:305). The performance decrease that followed stimulus reversal clearly indicated that the picture memory concept did not hold for the

stimulus reversal pictures, and was valid for the original pictures alone. 213

It might be pertinent to point out at this stage that while insight and experience account for some of the learning skills of great apes, observation of the responses of other primates also plays a significant role.

Observational learning can, in fact, be traced back to the period of mother dependence and forms part of the broader framework of social learning. Significantly, the affinity between the demonstrator and the observer is likely to be a determining factor in whether or not the observer learns from and imitates the behaviors of the demonstrator.

Crawford conducted studies which proved that observation could be used to effect cooperative behavior in the performance of a particular task, but this cooperation was not necessarily transferred to new tasks.

Just as primates are capable of imitating the responses of one another, so they are also capable of selecting stimuli that are identical to others and they have the ability to match samples (Nissen, Blum and Blum 1948:68).

The results of studies have indicated that primates are capable of learning more than specific responses to specific objects presented to them. Robinson (1955) provided additional evidence of chimpanzees' abilities to differentiate two pairs of stimuli according to whether the pairs were comprised of identical or different stimulus elements— homogeneous or heterogeneous (Rumbaugh 1970:28).

Nissen and his associates also tried to study the matching behavior of chimpanzees in a conditional context— one in 214 which the cues to be matched were contingent upon still other cues and events (Nissen, Blum and Blum 1949:349). The study was aimed at determining the degree to which the chimpanzees could process several units of information in combination for the determination of correct responses. Due to the complexity of the problem, the progress of the chimpanzees was slow and the researchers concluded that the conditional responses itself was probably a relatively minor

factor contributing to the difficulty. Sources of confusion and frustration for the subject seem to lie in the shift of cue values in progressive stages of training and the changes of effective cues during the study (Nissen, Blum and Blum

1949:355).

The delayed response problem has been widely used by researchers because it is sensitive to a wide spectrum of variables as well as a host of situational and response modes of behavior in which the subject might engage during

the delay interval. The experiment most commonly used is to place some incentive (such as food) which the subject is

expected to obtain after the elapse of a predetermined period of time. Successful performance in these experiments

depended on such variables as spatial and visual cues and

size and color of the food incentive. Davenport and Rogers

(1968:674) compared the delayed response of differentially

raised chimpanzees. In the early stages the restricted

chimpanzees were less task-oriented than were the wild-born

chimps, but with experience they quickly approached the 215 wild-born performance level. This indicates that in the chimpanzee, restricted early rearing produces behavior characteristics which hinder learning at a later age.

Later, however, a course of prolonged training can compensate the effects left by a restricted environment. It might be pertinent to point out here that Johnson’s studies of identical twin rats indicated that early environmental enrichment or deprivation influenced later problem-solving ability (1963:748). Other studies have shown that chimpanzees with experience perform better in different tests than those without prior training. Experiments conducted to evaluate the effects of delayed reward on the learning process indicated that chimpanzees without prior benefit of experience specific to color discrimination tasks were handicapped when reward for correct choices were delayed while chimpanzees with prior training were not

(Rumbaugh 1970:33).

The results obtained from patterned string problems are regarded as an accurate test of perceptual and insightful learning ability. Moreover, they are even more advantageous because in this type of problem comparative data is available on chimpanzees and young gorillas as well as monkeys (Fischer and Kitchner 1965:337). Chimpanzees and gorillas indicated almost equal ability in these problems as did orangutans. Similar, though somewhat simpler,

experiments indicated that gibbons were superior to 216 chimpanzees (Rumbaugh 1970:34) although there are no results for experiments involving complex problems which would be a more accurate index of their ability.

Tool use by nonhuman animals was originally thought to be the product of an artificial environment, a type of behavior that was essentially forced upon an animal (Scott

1972:166). However, it has been found that chimpanzees living under natural conditions use tools (Goodall 1971:241).

They have been observed to use sticks and modify stems to be used in termiting. While most chimpanzees do not venture more than a few yards to acquire a satisfactory "tool" for termiting, one male was observed twice to carry a tool for a distance of over one-half mile, inspecting and rejecting a number of termite heaps until one was chosen (Rumbaugh 1970:

35). Chimpanzees and orangutans have often been known to pick up sticks and branches to throw them at threatening predators and there have been observations of chimpanzees using probes and levers to pry at lids of banana boxes.

Behavioral scientists at the Delta Regional Primate Center observed chimpanzees using twigs and sticks as rudimentary toothpicks with which they clean their own and their fellow chimpanzee's teeth (Newsweek 1973:73). The chimpanzees modified the twigs by stripping off the leaves and chewing the ends. On one occasion a loose tooth was extracted and exmained.

Goodall has emphasized that learning and imitation are precursors of successful tool-using behavior. How this 217 behavior was first learned is difficult to understand and it has been assumed that opportunity, experience and certain unlearned behavior propensities, such as investigating and manipulating, combined to produce them. Much of the tool using that occurs in captivity appears to be a direct result of insight and manipulation rather than of imitation. Due to the monotony of captive environment, apes use tools more in captivity than in the field, if given the opportunity.

Studies of tool use have indicated that animals are capable of a considerable degree of organization of behavior, apart from that set up during the process of development and therefore largely governed by heredity (Scott 1972:165).

Schiller's study of complex responses (19 52) led him to believe that the innate constituents that provide for successful performance in problems, such as box stacking, are not perceptual organizations. Menzel has argued that

Schiller's "motor patterns" are not to be accounted for as innate since a comparison of the development of tool-using behaviors in wild-born and restriction reared chimpanzees revealed that the restricted chimpanzees were deficient in their performances even though they seemed to have the same repertoire of hand movements as did the wild-born ones.

Restriction reared chimpanzees lack the predisposition or are unable to expand upon basic elements of responsiveness to refinements of perceptual motor patterns. These motor patterns are the requisites for skillful tool use (Rumbaugh

1970:45). 218

One way of determining the learning skills of great apes is to demonstrate whether or not nonhuman primates have the capacity to utilize abstractions, a feature on which man's language system depends. Ferster and Hammer (1966) conducted an automated experiment designed to test arithmetic skills. In this test the chimpanzees were able to write by selectively pressing or not pressing each of three keys to provide a binary number. In the first experiment they were required to duplicate the binary numbers provided in a sample row, and though they did this successfully, it became evident that what the animals had learned was the likeness between specific physical stimuli rather than the abstract concept of identity itself (Ferster

1964:101). Rumbaugh (1970:47) has indicated that while monkeys and chimpanzees are able to acquire the concept of

"threeness" and the concept of "middleness" in separate experiments, there was no success in an experiment in which a chimpanzee was required to associate a number of cue shapes to a corresponding number of shapes on a box.

Ferster and Hammer (1966) seem to have had some success along these lines, however. In subsequent experiments on numérosity the chimpanzees were required to match a binary number to a number of objects, such as triangles. At first it appeared that the chimpanzees were memorizing the sequences or relating the number to the formation of the objects. When these extraneous cues were eliminated, it was found that two chimpanzees had actually succeeded in 219 learning the abstract concept of numbers and had acquired the rudiments of numeric skills.

Researchers have also been studying language-type skills in non-human primates with a view to determining their ability to form concepts. The Hayses taught their chimpanzee Viki, to say words like "papa", "momma" and

"cup" but it was extremely difficult for the animal to master the sounds required by these words. The next experiment involved the development of sign language much like the American sign language of the deaf with a chimpanzee subject (Gardner and Gardner 1969:664). The chimpanzee, Washoe, acquired a relatively good command of the sign language. This was not attributed to imitation but to the abstraction of regularities and relations from the language which the chimpanzee used for building up language for herself. In other experiments done by the

Premacks (Premack 1971; Premack and Premack 1972) a chimpanzee, Sarah, was taught to use plastic symbols for words and her performance indicated that her understanding went beyond the meaning of words and included the concepts of word class and sentence structure. The latest experiments in this area involve the use of a computer through which researchers at the Yerkes Regional Primate

Research Center in Atlanta are attempting to teach a chimpanzee, Lana, to read and write. A special language,

Yerkish, has been designed for this purpose and it comprises nine simple geometric figures that can be superimposed on 220 each other to form lexigrams that stand for various concepts. The lexigrams are displayed on a typewriter-like computer keyboard that Lana has learned to use to type out grammatically correct requests for food and entertainment

(Trotter 1973:360; Fleming 1972:7). A significant question still remains. Is Lana learning a language or is she being conditioned? Dr. Rumbaugh admits that Lana seems to be in an advanced stage of conditioning at the moment but adds that the project is designed to go beyond word learning.

There is a grammar and a syntax and researchers hope Lana can use words in a novel way to be linguistically productive

(Trotter 1973:361).

Considerable research has been done on the learning skills of great apes but chimpanzees have been the subject of most of this research. Relatively little is known about the learning skills of other apes. As Rumbaugh and

McCormack (1967) point out, there is much overlap in the distribution of learning capacities for the great apes. In studies where two or more genera of apes have been tested, after allowances have been made for age and experience, all great apes do equally well, though individual differences do exist in each case. It has also been established that chimpanzees are sensitive to human approval or disapproval and are, therefore, very easy to condition while gorillas and orangutans are much more difficult to motivate.

Generally speaking, great apes possess a plasticity, a problem-oriented adaptability far beyond that of monkeys. 221 and this adaptability is presumed to reflect increased reliance on the process of learning and experience as opposed to instinctive or unlearned behavior patterns

(Rumbaugh 1970:64). Suffice it to say that research to date is consistent with the conclusion that great apes are behaviorally as well as neurologically more similar to man than either gibbons or monkeys. They excel in situations that demand the use of multiple cues or the relational process, and also in tasks that involve delayed response, tool manipulation and numeric skills. Another indicator of learning skills which places great apes over other nonhuman primate forms is their ability to demonstrate innovative behavior patterns— a characteristic that needs to be discussed more exhaustively.

INNOVATIVE BEHAVIOR

One of the main features that differentiates great apes from other primates is their innovative behavior patterns and their ability and willingness to "devise" new behavioral responses. For the most part, the innovative behavior stems from some kind of experience that the primates have previously been exposed to, but the true criterion for innovative behavior is the complete absence of any form of conditioning. The behavior is self-sustaining and not contingent upon any extrinsic incentive that may be

ingested. Furthermore, such behavior is to be distinguished 222 from other responses that reflect only curiosity and manipulation per se (Rumbaugh 1970:57).

While a theoretical definition of innovative behavior is essential, it fails to capture the true nature of the behavior itself. Therefore it would be pertinent to outline some behaviors that are considered essentially innovative. Usually it is insight and experience that produce the invention. Imitation often spreads the behavior pattern throughout the group (Riopelle 1972:368). The experience that forms the basis for the creative activity may come either from the formal testing situation or from incidents in everyday life. The innovative behavior of

Washoe can be traced back to physical care. Washoe (the

Gardners' pet chimp) received regular baths and one day was observed to bathe one of her dolls in exactly the same way that she was bathed. She filled a small tub with water, immersed and soaked the doll and finally dried it. Thus

Washoe became the giver and not the recipient of the bath

(Rumbaugh 1970:56). In this case it was easy to associate the innovative behavior with its original source, but in other cases the behavior seems to be based on greater

insight.

One of the classic cases is that in which E.W.

Menzel outlines the spontaneous invention of ladders in a group of young chimpanzees (Menzel 1972a;87). Eight wild- born chimpanzees between 6 and 7 years of age were provided with several climbing objects. In the first several months 223 of their captive existence they were not known to deliberately stand a pole or stick vertically and then climb

it. They would, however, climb any object that was positioned in a way which permitted climbing. One day a chimpanzee was seen to position a large food tray vertically and to jump from its top. Thereafter they were provided with a broom. Within a couple days they were observed to

stand the broom upright on its bristles, scramble up the pole and then jump from the top to the ceiling rafters

before the pole lost its balance. There were two features

that characterized this early activity— it was repeated time

and time again without any goal or objective, or any

external motivation; another remarkable feature was that while the chimpanzees stood the broom at a 90 degree angle,

they were never observed to prop the pole against another

structure in order to climb it.

While the stages that led to the "invention" of

ladders were not clearly demarcated, we may say that a

second stage was reached when the chimpanzees used a pole to

enable them to reach an observation house that was otherwise

out of reach. The fact that the pole was repeatedly used

for the same purpose convinced the observers that it was not

simply a chance response, but when the pole was confiscated,

the chimpanzee made no attempt to replace it with another

pole though there were several in the vicinity.

The third stage was reached about a week later when

the chimpanzees transported a pole to the observation house. 224 positioned its base against the ground and propped its top directly against the wall. Subsequently, when all the poles in the vicinity were removed, the chimpanzees were seen to break off the ends of old dead tree trunks. As

Menzel reports:

On three occasions we observed Rock leave off trying to peer in the window with a short pole, walk 15 ra or more to a fallen tree, break off the tip end of the trees (which weighed more than 15 Kg.), drag it over to the observation house and set it up as a ladder (Menzel 1972a:98).

This clearly indicated that he had not only constructed the ladder but had also constructed and transported the raw materials for his construction.

The final stage comprised the transfer of the ladder-making performance from the observation house and its use to circumvent the shock wire that had been placed around trees to prevent the chimpanzees from climbing them. At around the same time, another behavior pattern was developed. Instead of physically carrying the pole up on to the runway, the chimpanzees set it up as a ladder from the ground to the runway, ascended it and then hauled the ladder up after them; then again set the ladder up from the runway to the tree. While this behavior pattern was initiated by one chimpanzee, Rock, his skill soon passed into the general repertoire of the group as a whole, and was subsequently used for new purposes (Menzel 1972a:101). The other chimpanzees did, however, have some difficulty in mastering the technique, for though they did not lack the necessary 225 motor responses for constructing the tree-ladder, their failure lay in not visually attending to the base-ground connection. It is interesting to note that not only did the chimpanzees try to observe, manipulate and control their environment, but the findings of each of their subexperiments were cumulative and became shared knowledge and tradition of the whole group.

Thus we may point out that several behavior patterns that are now generally accepted as characteristic of chimpanzees were, at one time or another, innovations which were subsequently passed on to a group and became permanently associated chimpanzee behavior. One significant aspect of this experiment is that it appears that ladder- using was influenced by social experience. Socially deprived chimpanzees were inferior to wild-born chimpanzees in performance and cross-cultural comparisons indicated differences in performance among even wild-born chimpanzees.

The interest of individual chimpanzees and the spirit of cooperation and collaboration also affected individual performances in the ladder-using process.

This observation seems to negate the theories of

Schiller (1957:264-287) and Hall (1963:479-494) which claimed that primate tool using can be reduced to certain ■

"innate movement patterns" and that seemingly intelligent performance is the chance occurrence of one of these movement patterns in a situation in which it is likely to be reinforced. This observation, however, indicates that in 226 ladder using the most significant "behavioral elements" involve attention to and perceptual differentiation of specific consequences of the stick's contacts with other objects (Menzel 1972a:101). In other words, the process demands that the primate take into consideration the relation between the animal himself, the stick, the ground and the tree. The chimpanzee comes to treat the stick as a functional extension of the arm (Birch 1945:375) as well as a portable extension of the environment. We can, therefore, safely claim that ladder using does not result from the reinforcement of chance movement patterns, but that it is indeed an innovative behavior pattern.

Menzel, Davenport and Rogers have conducted some experiments to prove that wild-born captive chimpanzees often show immediate and apparently intelligent solutions of laboratory tests of tool-using, whereas chimpanzees that have been separated from the mother at birth and raised under controlled conditions acquire the same performances slowly or not at all (Menzel, Davenport and Rogers 1970:273).

The results of the experiments go far beyond the theories of

Schiller who claims that if restricted animals are given the opportunity to use their innate manipulatory drive, and are also provided with reinforcements, they usually become skilled tool users (Schiller 1957:286). He maintains that these are instinctive activities simply in need of reinforcement. 227

But the studies of Menzel, Davenport and Rogers

indicated that wild-born chimpanzees solved tests more quickly and more intelligently than their restricted counterparts. In fact, what the restricted chimpanzees really lacked was adaptability or the ability to apply whatever skills and propensities they had to new situations

(Menzel, Daveport and Rogers 1970:280). They also showed restricted ability in dealing with objects that were temporally or spatially remote. The authors concluded that intelligent and innovative behavior manifested by wild-born

chimpanzees was less dependent upon the available repertoire of hand movements or even hand-stick correlations, and

infinitely more dependent upon the repertoire of potentially

available instrumental aspects of manipulation or eye-hand-

stick correlations (Menzel, Davenport and Rogers 1970:281).

These authors also point out that tool using ability does

not lie in the hands alone, in the central nervous system

alone, or in the environment alone, as earlier accounts tend

to imply, but in some luck interaction and isomorphic fit

between them (Mason, Davenport and Menzel 1968:78-85).

While manipulatory drive, matured motor patterns and

operant conditioning are necessary for certain performances,

they cannot be considered adequate to account for

"intelligent and innovative" behavior. It appears that the

most significant factor determining innovative behavior in

primates is a predisposition to continuously expand upon and

refine whatever spatial skills and object skills are 228 available in their repertoire {Menzel, Davenport and Rogers

1970:282).

It is this very ability to adapt themselves to their surroundings and to expand upon their available repertoire that distinguishes primates from other creatures and places them in a category not far removed from man. Jane Goddall who has studied chimpanzees at the Gombe Stream claims that the chimpanzee with his capacity for primitive reasoning, exhibits a type of intelligence more like that of man than does any other mammal living today. She speculates that the brain of the modern chimpanzee is probably not too dissimilar to the brain that so many million years ago directed the behavior of the first ape men (Goddall 1971:

241). The author goes further to point out that the innovative behavior that leads to tool using in chimpanzees can be compared with the innovative behavior of prehistoric man that led to the use of tools and was the major criteria in distinguishing him from other creatures.

Goodall writes in detail about several innovative behaviors among wild chimpanzees and she points out that the criterion that distinguishes these as innovative behaviors is the adaptability that characterizes them. While termiting is commonly observed among wild chimpanzees the most remarkable feature of this behavior is the ability of the chimpanzees to modify stems in such a way as to make them more effective as tools. In one particular case the innovative pattern was even more marked. While most of the 229 chimpanzees obtain their tools from the vicinity in which they are termiting, one male was observed to go distances over a half mile in order to secure appropriate tools.

Another innovative behavior pattern that indicated the ability of chimpanzees to modify tools for a required purpose was their use of leaves to sop up water which they

could not reach with their lips. They were even observed

to chew on the leaves in order to increase their absorbency.

Goodall also observed that leaves were used to wipe dirt

from the bodies of chimpanzees as well as to dab at wounds.

With reference to these innovative behavior patterns Jane

Goodall aptly remarks :

The point at which tool-using and tool- making, as such, acquire evolutionary significance is surely when an animal can adapt its ability to manipulate objects to a wide variety of purposes, and when it can use an object spontaneously to solve a brand-new problem that without the use of a tool would prove insoluble (Goodall 1971:244).

Aside from adaptability and modification which have

been found to be essential characteristics of innovative

behavior, another major characteristic requiring emphasis is

the redefinition of materials (Rumbaugh 1970:58). This

characteristic can best be illustrated by the use of a few

examples: stems are redefined as implements that can be

used to obtain termites; sticks and stones are seen as

missiles to be hurled at possible predators; a doll is no

longer simply something to be played with, but comes to

represent the chimpanzee himself; the bathtub is used as a 230 receptacle to hold something other than himself; a pole is no longer considered a plaything to be aimlessly climbed and jumped off, but comes to represent a means to an end— be it a ladder to circumvent the electrical wire or to reach the observation house. In short, it may be said that in order for a primate to innovate behavior, a form of relational or ideational behavior is essential. The primate has to be able to see and to learn about the functional roles of select elements involved in certain experiences.

Thereafter, he must also have the ability to reassign elements with regard to functioning roles (Rumbaugh 1970:58).

In the final analysis, contrary to the basic tenet of Thorndikian associationism which emphasizes the development of associations between stimuli and responses, primates do manifest innovative behaviors which are self­ indulged and self-sustained. Here the great apes acquire stimulus response associations and learn about those associations and about experiences they have had. The innovative behaviors observed in apes are characterized by the ability of the animals to modify, adapt and redefine the materials used and, to the best of our knowledge, such highly innovative behaviors have not been reported in any form of monkey (Rumbaugh 1970:57). Chapter 6

REINTRODUCTION AND REHABILITATION OP CAPTIVE AND DISPLACED ORANGUTANS

It has been documented that primates, particularly the great apes like the orangutan, are being threatened with extinction. There are no accurate statistics indicating the number of orangutans existing in the wild but the populations are known to be dwindling. In certain areas it can be seen that the infant proportion of the population has steadily decreased and that reproduction has virtually ceased since 1968 (MacKinnon 1974:19). For some time now, considerable emphasis has been placed on breeding orangutans in captivity to help avert extinction and in recent years programs have been initiated to reintroduce captive and displaced wild-born orangutans to their natural environment in an effort to rehabilitate them and study their behavior in that environment. Orangutan rehabilitation centers have been opened in the Sepilok Forest located in the Malaysian state of Sabah, the Tanjung Puting Reserve in the

Indonesian sector of Borneo and the Leuseur and Langkat

Reserves in Sumatra. These reserves are inhabited by wild orangutans as well as by those in the process of rehabilitation and are now the few remaining natural living areas of the orangutan.

231 232

Perhaps the most well known of these rehabilitation centers is the Leuseur Reserve which is 10 kilometers away from the nearest human habitation. The rehabilitation station consists of a large mesh cage divided into four compartments (Rijksen 1974:22). When the animals first arrive at the center they are placed within a compartment.

Here they are observed for two to five weeks after which they are free to go anywhere they want. The aim of this program is to give the animals maximum freedom but a minimum of human contact and is oriented toward returning them to the wild. The main hurdles faced by the orangutans are the ability to search for food and to acquire social adaptability. One interesting aspect of this project remains to be observed: when a large number of rehabilitated orangutans with developed patterns of social behavior are introduced to an area already populated by wild orangutans, they may have a noticeable impact on the behavior of all orangutans present (Rijksen 1974:23).

The rehabilitation of orangutans is an infinitely more difficult task than it may appear to be. As Birute

Galdikas-Brindamour points out (1975:451), "At first Rod and

I had the idea that ex-captives, if only old enough, would

eagerly return to life in the forest..." but five years of

experience in the field proved how naive her early

assumption had been. 233

However, it is now believed that rehabilitation can be effected with success if emphasis is placed on relating réintroduction to dominant behavior patterns and ecology.

RELATION OF REINTRODUCTION TO BEHAVIOR AND ECOLOGY

Extensive studies of wild orangutans in their natural habitat have been conducted by several researchers and information regarding social behavior and ecology gained through these studies prove to be of great value to the rehabilitation programs. Laboratory studies conducted on other species of primates have also been of considerable importance in enabling primatologists to formulate effective réintroduction programs. Since early experience is a formative factor in the life of a primate, it has great implications with regard to rehabilitation. Experiments conducted on isolate-reared monkeys by Suomi and Harlow indicated that the damage inflicted on monkeys by isolation can be remedied if réintroduction follows a logical pattern.

The unequivocal findings that emerged from the data analysis were that isolate subjects developed significant behavioral abnormalities during the period of social isolation, the isolate subjects exhibited virtually no trace of emergency

trauma upon removal from isolation and most important, the

isolates showed significant recovery. This recovery was shown in terms of both nonsocial and social behavior in all

testing situations during the course of the therapy period

(Suomi and Harlow 1972:490). The net result of this finding 234 was that monkeys reared in total social isolation for the

first six months of life exhibited significant recovery of

virtually all behavioral deficits across all testing

situations after appropriate therapeutic treatment (Suomi

and Harlow 1972:493). The crucial factor determining this

recovery was the nature of social agents applied as

therapeutic measures— young, socially normal monkeys. The

isolate-reared monkeys did not respond spontaneously. The

first social interactions were initiated by the young

therapists who approached the isolates and clung to them.

At first the isolates seemed to be immobile, but after a

brief period of time they began to reciprocate. Once these

interaction patterns were established, the isolates

themselves initiated play bouts with progressively

increasing frequency (Suomi and Harlow 1972:493).

The rehabilitation period may be divided into two

stages. The first is breaking down previously established

patterns of abnormal, self directed behavior achieved by the

clinging of the therapists. The second is the development

of simple social behavior that later developed into a more

complex, socially acceptable behavior repertoire which

appeared to develop along with the behavior repertoire of

the therapist monkeys. Two stages appear to be both

important and relevant to the study of rehabilitating

orangutans. First, behavior that is not congenial and

appropriate to the natural habitat must be gradually

eliminated, then socially acceptable behavior must be 235

induced. If this finding generalizes not only to other

forms of early experience but also to other species, then

the implications of the present experimentation for reversal

of psychopathological behavior attributed to inadequate

early experience become enormous (Suomi and Harlow 1972:

495). A case in point is that of an orangutan, Winnie, who had been kept as a personal pet. In captivity she acquired

a taste for beer, cigarettes and an occasional whiskey. At

the Sandilok rehabilitation center these commodities were

not supplied but the craving for tobacco continued over a

long period and the animal would not hesitate to snatch

cigarettes from the staff (Kann 1972:2). Here, as in other

rehabilitation centers, the rehabilitation process consists

of two phases. The new arrivals are kept caged and offered

a good diet. After a period of time they are released and

encouraged to follow other orangutans out into the jungle.

After a brief period, it is not uncommon for them to wander

off, seldom returning to the rehabilitation center. Rijksen

details the early rehabilitation process (1974:23). After

their arrival at the center, orangutans are kept inside a

compartment and observed for two to five consecutive weeks

and sick or injured animals are treated. During these

initial weeks the orangutans meet other members of the group

and then are allowed to go freely wherever they want to go.

The principle of this type of program is to give the

orangutans maximum freedom but a minimum of human contact. 236

While discussing the role of early experience and the effect it may have on rehabilitation, it may be pertinent to discuss one significant point that has been

analyzed at length by Menzel, the effect of early experience on group behavior. He claims that a most important aspect of the primate's effective environment and critical

reference points for any activity is social in character.

That is, a majority of the variance in an individual's behavior is attributable to his reactions to other animals

(Menzel 1968:176). He goes on to explain that:

Even casual observation of primates is sufficient to reveal that the animals are practically never alone, and often exchange signals with neighbours; but only in the past decade have we become aware of the stability, internal complexity, and diversity of primate groups as a whole. As the term group implies, aggregates of individuals tend to compact themselves together in space, to remain together across time, and to avoid mixing with other aggregates (Menzel 1968:178) .

It must be pointed out that not all primates form

highly coordinated groups and as such it is difficult to

comment on the integrity of groups as wholes. There is also

no uniformity of opinion as to the dominant bonds that hold

a group together. All major social roles and classes of

bonds appear to develop as a result of initial socialization

by the mother. Possibly, as researchers have thought for

years, the relationships between older animals are simply

elaborations upon and redirections of the initial attachment

to the mother (Menzel 1974:178). Another significant fact 237 is that species-specific groups develop, evolve and adapt themselves to certain ecologies and thus group life may be said to be dependent upon environmental factors. In the case of the orangutan this appears to be especially true.

The male orangutan is generally a solitary animal and the orangutan population as a whole is usually split into small foraging units. The sighting of single males is most frequent, next females with a dependent infant and females with an infant and accompanied by a dependent juvenile, particularly an adolescent female (Harrisson 1972). A new infant is born every 3-4 years or more frequent if an infant is lost through disease or accident. Consort pairs are observed but the stability of the relationship is unknown and the peer bond is not well established, owing to a wide spacing of infants. Marginal contacts between adult females and their dependents are observed rotating in their individual ranges and none are agonistic. Similarly, marginal contacts are observed with rotating individual males whose larger ranges overlap. Males maintain spacing by long calls (previously identified as a mating call). The frequency of calls is approximately three times daily. Male to male encounters are rarely recorded. Calling males avoid encounters and are unsociable. Female orangutans do not react to calls. Adult males may respond by agonistic display, counter calls or quietly moving away from the calling male encountered. A call can also be triggered by a disturbance such as a crashing tree, animal noises or 238 rustling branches. It is still unknown how small units of consort pairs, females and dependents and circulating males and juveniles (male juveniles) fit into the cohesion of the larger group. There are indicators of regional differences but the difficulty is mainly in judging bonds given wide spacing and a majority of casual encounters where no recognizable interaction is involved. Another difficulty is that of recognizing individuals under different conditions of light and obstructions in high stories of forest where the animals tend to move. These findings of

Harrisson in 197 2 are substantiated by MacKinnon's 1974 publication.

The fact that groups are small does, in fact, reflect the effect of ecology and environment. The orangutans are largely fruit eaters and since the supply of seasonal fruit is of a limited nature, groups are necessarily small and search for food over relatively large areas. The diet is varied in accordance with availability and moisture take-up comes largely from the trees. Since the groups are not of a highly coordinated nature, orangutan rehabilitation becomes advantageous. DeSilva (1971) reports that solitary wild orangutans are often attracted to the rehabilitation center and are sometimes seen to leave with former inmates of the center. One reported case, Joan the insomniac, was raised by humans who kept a chain around her neck. When she arrived at Sandilok for rehabilitation and was freed from her chain, she found it difficult to sleep. 239

When her initial introductory period was over she left in the company of a wild orangutan and returned pregnant. It is unlikely that Joan had had much previous exposure to the wild or contact with orangutans successfully rearing their young. DeSilva's account (1972) indicates that Joan had a normal delivery and behaved in much the same way as a wild orangutan although she returned to the center to have her baby. Joan seemed to be able to coordinate two diverse cultures in order to effect a harmonious life of her own.

For more than six months after the birth of the infant, Joan permitted no interference from humans or orangutans but

gradually became more relaxed. If her confidence was gained, she would allow the infant to be stroked by members of the staff (DeSilva 1972:105).

Since early experience is so important for

successful adaptation, the rehabilitation centers in Borneo

aim to emulate the early experience of orangutans by keeping

in mind the fact that very young orangutans seldom encounter

strange things alone and unaccompanied. At the orangutan

rehabilitation centers it is hoped that other inmates will

assume what would have been the maternal role in wild life,

for it is known that from birth an orangutan travels with

its mother. Inmates at the center, just like infant

orangutans, must learn to navigate to remote points,

establish limits on "free space" with respect to geography

and predators, cope with animals and objects on his own and

eventually lead others and serve as a focal point and home 240 base for them (Hall 1968:181). Locomotion is a steady and continuous progression from the familiar to the unfamiliar, exploring both social possibilities and environmental features from an established base.

While group members are of great value to new inmates under rehabilitation, it must be remembered that studies of monkeys have shown that primates reared without a mother are handicapped when they later try to relate to an adult environment. Several experiments have indicated the effects of maternal deprivation and in recent years considerable emphasis has been placed on the provision of a foster mother rather than a surrogate mother. Foster mothers are capable of providing a constant source of stimulation and motivation conducive to behaviorally normal growth. Bernstein (1971:73) illustrates a successful case of introducing a foster mother to laboratory born infant monkeys. A pigtail macaque female who was unable to conceive was chosen to care for two infant monkeys, only one of which was a pigtail macaque. She carried the younger infant in the normal ventral-ventral position with the older one on her back or to the side of the younger. Although she was nulliparous, after two months passed she began lactating in response to the suckling of her adopted infant. At

Yerkes Field Station other adult females have been used as foster mothers to prevent the development of bizarre stereotypes characteristic of infants raised in deprivation environments. The foster mothers permit technicians to 241 handle the infants, give supplemental feedings and medical care and the infants appear to be psychologically and sexually normal when adulthood is attained. Moreover, the laboratory has found this a less costly method of hand rearing infant monkeys.

Aside from the impact early experience has on the degree of success of rehabilitation, the age of the primate being introduced is also an important factor. Research has indicated that in the case of adaptation to captivity, younger gorillas usually fare better than gorillas over four years of age {Sabater Pi 1967:156). By extension it may be inferred that, in reverse, orangutans being introduced to freedom will adapt better if they are young adolescents.

Rehabilitation centers cannot choose the age of the orangutans they try to help. It is so important to build up a free orangutan population that every individual confiscated or orphaned is accepted regardless of his potential for successful rehabilitation.

Although individual behavior traits can affect successful réintroduction, ecology is a most important factor in the rehabilitation process. The changing nature of the environment appears to have an adverse impact on the natural existence of the orangutan. Orangutans are becoming scarce because of habitat destruction and encroachment perpetrated by the logging industry (Mydans 1973:27). While the concept of reintroducing captive orangutans to the wild appears to be a move in the right direction, the species 242 would do much better if the emphasis were placed on preserving the environment and ecology native to the animals. Lindsey (1968:421) has outlined the effectiveness of the individual ecologist in the preservation of natural areas and has indicated that local preservation work has proved congenial to biologists since it avoids militancy, controversy and politics by remaining largely in the private secot. In order to save the orangutan environment from destruction, however, it was necessary to have individual help along with government legislation since environmental alteration persists and is inadequate to support the local species. Herman categorizes environmental destruction as a form of disease causing the depletion of a specific species:

It is life outside of a zone of normalcy taking into consideration age, sex, race, geographical distribution and any other attribute that is disadvantageous to the species (Herman 1969:321).

Disease, in this context, comes to connote the product of an adverse habitat. Ironically, even when all factors in the habitat are favorable to a species, disease still can become a controlling factor. Favorable habitat may develop an overpopulation out of proportion and again result in a situation disadvantageous to the species.

This is particularly significant with regard to the orangutan which seems to thrive best in a population density of one orangutan per 1.5 sq. miles (Toshiba 1964:24). The density of population is usually estimated by counting orangutan nests on the assumption that an orangutan makes 243 one nest per day and that the nest remains visible for almost six months. Higher densities of orangutan population have been reported in some areas but this has been attributed to human disturbance causing orangutans to move from a disturbed area and gather into a small patch of undisturbed area.

Food availability is one of the most important factors that regulates the pattern of social organization as well as the density of population in a particular area.

Although fruit availability seems to be unpredictable, orangutans seem to have an uncanny ability of arriving at the right time at the right place. MacKinnin observed:

I rarely discovered a new food source before they (orangutans) did. They often proceeded to new fruit trees by very direct routes although I believed they had not fed there previously that year. ... Whatever their methods they are certainly very efficient at finding small, rare dispersed sources of food. Of all the arboreal species, orangutans seemed to crop by far the largest portion of edible fruits in the Borneo forest. In view of this, the relatively solitary way of the orangutan seems to be well adapted (MacKinnon 1974:31).

When overpopulation beyond the food capacity occurs, starvation and fatality is often the end result. Often these losses come to be associated with disease causing organisms such as parasites, bacterial and viral agents.

Disease is often an expression of lowered resistance and results from malnutrition. This indicates the importance of maintaining an ecological balance of all factors if a 244 population is to be controlled. While changes in habitat can increase or decrease the potential of population density, healthy populations must keep within the

limitations of their habitat or adverse factors such as disease will come into play to establish the balance

(Herman 1969:322). While there is limited documentation

that disease as an individual factor can drastically affect population fluctuations, it is evident that, acting with other ecological phenomena, disease can have an extensive

impact. Herman (1969:325) states that it is difficult to overemphasize the dependency of the occurrence of disease

in wildlife on habitat conditions, and ecological relationships.

In the concern of orangutan rehabilitation, considerable attention should be given to the environment in which orangutans are raised in captivity as well as the most

congenial environment in the wild. The more natural the

captive environment, the more readily the orangutans adapt

themselves to a new life. In an incisive analysis, Reynolds and Reynolds (1965) have outlined ways a captive

environment for chimpanzees can be made more physically,

socially and motivationally stimulating. By extension, the

same or similar ideas can be used for adaptation of captive

orangutans.

In aspect of physical environment, trees form an

essential part of orangutan life providing food, defensive

weapons as well as a nesting place. Although the 245 traditional concept of orangutan behavior indicates that these primates are arboreal and spend the major part of their lives in trees, more recent observations suggest they

spend more time on the ground than had been previously believed (Galdikas-Brindamour 1975:444). Long periods of

captivity can cause atrophy of limbs when exercise

facilities are not provided as the orangutan in the wild uses a tree for climbing, hanging and swinging. One case

study, Moses, reports captivity in a small cage over a long enough period of time to cause atrophy of the legs (Kann

1972:1). Rehabilitation will never be totally successful

for this animal has had greatly difficulty in learning to

climb trees and may never be able to do it well. With some

effort, the proper exercise equipment can be provided to

replace trees but other needs are also satisfied by the

presence of trees. Galdikas-Brindamour reports an incident

in which a hostile female, Cara, dropped a log upon her

during an observation period (1975:452). Branches of trees

are often used as display props during threatening

situations, being swung underarm, thrown to the ground or

pulled down with violent overarm movement. The trees

provide both the site and the materials for the construction

of sleeping nests. Nest building in orangutans is a species

characteristic behavior pattern. The construction

mechanisms resemble those of chimpanzees, holding the

branches down with the feet and twisting them to form a

concave platform. Occasionally orangutans have been known 246 to build nests on the ground in the day which are built on fallen logs. Galdikas-Brindamour (1975:449) reports the actual observation of a wild subadult male who slept for 45 minutes on the ground during the day. Occasional ground nests had been discovered up to this time but field workers had attributed them to practical jokes of co-workers or to confusion of heights in the orangutan as one was found on the edge of a cliff. Galdikas-Brindamour was the first person to actually observe an orangutan sleeping in a ground nest. Frequently orangutans being introduced to the wild do built nests on the ground (Harrisson 1969) . Juveniles learn the technique of nest building long before they need to be self sufficient and have frequently been observed to build play nests. Orangutans further use branches to make overhead shelters for their nests when it rains or when the sun disturbs their afternoon naps (MacKinnin 1974:51). No doubt, if trees were provided in a captive environment or manipulative material as suggested by Barbara Harrisson

(1972) orangutans would adapt better to a more natural environment. While nest building can be stimulated and improved by copying or learning from more experienced animals, there is a strong indication that these skills can be developed independently. Jacob, an orangutan that escaped from the Regents Park Zoo, made a satisfactory nest in a nearby tree although he had had no opportunity to observe other animals make nests and had not had experience with natural branches in the zoo (Bernstein 1962) . 247

This indicates that all the vital needs supplied by trees in wild life can be met in a variety of ways in captivity. Food can be provided as can objects to exercise with and to use for purposes of display. However, trees do form an inextricable part of an orangutan's natural environment and if rehabilitation of a particular primate is intended, it is always advantageous to introduce the orangutan to phenomena that it will encounter when it is reintroduced into the wild or into a semi natural habitat.

Some records of the rehabilitation centers indicate that captive orangutans refuse to go anywhere near trees when they are placed in a wild situation and wardens must chase them up trees in order to force the necessary association.

This becomes a stressful situation that might be avoided if orangutans could be introduced to natural phenomena even in their captive environment.

The social needs of the orangutan must also be met

in captivity if rehabilitation is to be successfully effected. While the orangutan does not appear to be as

social and gregarious as some other primates, social

interactions do occur. Although the lone, solitary adult male and the adult female with offspring are the most

commonly observed, MacKinnon (1974:51) has observed a

consort relationship temporarily linking a mature male to a

mature female and an immature, independent animal

occasionally joining another subgroup. From these types of

patterns, it is not difficult to provide the orangutan with 248 the kind of social companionship he might know in the wild but particular attention should be paid to the great stability of the mother-infant bond. Juveniles should not be separated from their mothers for the first two years of life. Reynolds (1965:143) states that to separate the two at a very early stage may have harmful effects on the subsequent sexual and parental behavior of the offspring.

If possible, when a motherless youngster is received or if

it is necessary to separate an infant from its mother, the youngster should be kept with another of its own age. Even

a youngster of a closely related species will help provide peer socialization for research has shown that in the absence of a mother, the company of age-mates goes a long way towards normalizing the development of behavior. In the wild, juvenile orangutans seldom have an animal of their own

size with whom to match their strength and agility. Often when a more suitable play peer is present in a nearby

subgroup, juveniles cross over to play although the

respective adult females show no inclination to link up. As

juveniles become older the bonds with their mothers become weaker and during adolescence they gradually develop their

own home range (MacKinnon 1974:60). Generally, all

orangutans seem to enjoy company but it is important to match their ages as much as possible. Harrisson (1961:68)

feels that two together adjust themselves better than three.

Moreover, these attachments grow so strong that it must be

kept in mind that babies who have been brought up together 249 should not suddenly be deprived of companionship to which they have become accustomed.

Finally, great emphasis should be placed on motivating captive orangutans. In the wild, an orangutan's chief motivation is the constant quest for food which occupies an average of 6.3 hours a day (MacKinnon 1974:21).

Barbara Harrisson (197 2) compiled the reports of MacKinnon and another observer, Peter Rodman, during their studies in the reserve. She learned that the daily activities of the orangutans varied according to whether or not the animals were habituated. Non habituated animals spent 6 8% of their time resting, 17% feeding and 15% moving. Habituated orangutans rested 4 2% of the time, fed 45% and spent the remaining 13% moving. Captive orangutans who are dependent on being fed spend more time feeding than animals who must forage for themselves. A captive orangutan supplied with the requisite quota of daily food is reluctant and even unwilling to learn to forage in the wild. In most orangutan rehabilitation centers, the inmates continue to be fed twice daily by wardens who call out their names and summon them to meals. During the fruit season, however, the daily meals at the clearing are reduced to encourage the orangutans to forage for their own fruit (Kann 1972:2). Mydans (1973:28) tells of the difficulties inherent in this aspect of rehabilitation. Some of the animals present a problem which is largely derived from orangutan memory since they have not forgotten that humans provided for them in the past. 250

Although most of them become capable of living in the wild, they keep returning irregularly to the rehabilitation center for the fruit they were once accustomed to receiving.

There are other types of motivation that are basic to orangutan life but which cannot be adequately provided for in a captive atmosphere such as motivation to maintain social boundaries or home ranges and the unique call that threatens any male violator. Stanley DeSilva, who conceived the idea of the halfway house for orangutans, points out that the absence of motivation can really hinder the cause of rehabilitation. Many unmotivated orangutans continue to return and finally the wardens must force them to take the final step. The link with humans is so hard for them to break that even though they have indicated readiness and a capability to care for themselves, to deal with this problem the wardens take all the suitable animals remaining and carry them to distant areas of the forest, far away from human habitation, where they are released (Mydans 1973:29).

One of the major problems in setting aside reserves and fully rehabilitating orangutans has to do with the expense involved as orangutans are wasteful and destructive

in their natural habitat. For a zoo or laboratory to attempt to construct a totally natural reserve would be both

impractical and financially overwhelming. The cost of maintaining the environment, lack of space and lack of manpower time are all understandable difficulties. Barbara

Harrisson's account of orangutan behavior in a semi-wild 251

State shows us that orangutans are inclined to destroy their environment through compulsive "fiddling" with whatever they find:

At least part of this 'fiddling' is closely related to the movements (mainly of hands) made during the nest building, when branches and leaves are turned and twisted and often tried out in various positions before a final one is settled on, and the branch put and patted neatly into place. Creepers are often woven into it, and ropes, chains, wire, string, etc. seem to appeal as substitute nest building material thus to be used in play. The urge to destroy and to take to pieces is closely related to the orangutan's attitude during feeding when only a fraction (usually the best part) is eaten, and the rest is left to waste. But when observing the orangutan intimately one gets the distinct impression that, quite apart from the urge to feed and to build nests, it is the tremendous, ceaseless curiosity that also governs these activities and that lets the orangutan be content to be at rest, watching and observing (Harrisson 1961:68).

This first hand knowledge cannot help but make one wary of paying such a high price for the rehabilitation of orangutans. When expense and space play such important roles, imagination must be used in creating artificial substitutes and making the best use possible of cramped quarters to give an orangutan sensations of height, variety and independence. Emotional well being is as important as physical health if an orangutan is to be effectively introduced to the wild, to a semi-natural habitat or even to another orangutan in captivity. 252

FUNCTIONAL AND ADAPTIVE ADVANTAGES

The chief aim of rehabilitating orangutans is to make them independent of human guardianship and to get them back into the wild for breeding purposes. We have already discussed the behavioral and ecological factors that must be taken into consideration in order to effect successful rehabilitation. Judging from the projects that are already underway, the two most feared prospective hazards for captive orangutans— the ability to search for food and the ability of social adaptability— have not proved so formidable after all. With regard to the search for food, the orangutans simply try everything on their way that looks edible: fruit, flowers, leaves, shoots, bark, pith, herbs, and insects. Every unfamiliar object is sniffed and tested and if it proves to be edible, soon the other group members will detect it as well. The orangutans very readily learn from their group members. Presumably, the same manner of food searching is practiced by the wild animals as it seems unlikely that they know all the different food plants and fruits of the rain forest (Rijksen 1974:24). Social adaptability has not proved too traumatic because the only relatively stable subgroup is that of infant and mother and therefore, social behavior does not seem to be dependent upon a highly organized behavioral repertoire although field studies are so young that we may not know for sure for several years. The reasons orangutans seem to move in small 253 groups or individually is probably due to the dispersal of food in the habitat as well as the fact that they live in a relatively small substratum— the branches of the canopy.

Consequently, social behavior in the orangutan is less obvious and less differentiated than in the more social primates. However, under the unnatural conditions prevailing in the rehabilitation group, the animals show a more conspicuous social behavior. This, like their communication system, seems to be more closely related to the behavior in other sociable living apes (Rijksen 1974:24).

Another aspect in which project animals differ from wild orangutans is in their manipulative ability, throwing skill and use of objects. Sticks were often used as tools during locomotion or to get hold of a branch that was out of reach. Stanley DeSilva (1971) indicates that semi-wild orangutans in the rehabilitation center often display

"un-orangutan-like" behavior which has obviously been influenced by what they watched humans do while the primates were in captivity. Mydans (1973:30) recalls how Joan once used a dead branch as a club to pound a hole in the ground much as a man might pound in a fence post. Stanley DeSilva stated:

If an anthropologist saw this display and knew this animal was wild, he would be beside himself with excitement. 'A wild animal using tools!' It would be of major significance. But this animal is semi-wild, and what you are seeing is not an ape that has discovered the use of tools, but one that is simply remembering things that she has seen humans do (Mydans 1973:30). 254

Wild orangutans, on the other hand, appear to have relatively few manipulative skills, and these are generally limited to building nests. During displays, wild orangutans often break off branches which they drop on the ground and although they sometimes manipulate these branches before letting them go, the drop is nearly always vertical (Rijksen

1974:24). Unlike chimpanzees, they are incapable of guiding their missiles in any particular direction.

In a very real sense, these semi-wild orangutans have totally different behavior patterns that, incredibly enough, often reflect the personalities of the humans they had lived with just as the personalities of children are fundamentally influenced by their parents. There are some particularly interesting cases like that of Winnie who had been taught to smoke and to consume alcohol, and often took cigarettes away from members of the staff at the rehabilitation center. There are other cases, too, that indicate the adaptation of behavior patterns that are totally alien to wild-born orangutans. Arthur who had a violent background and destroyed everything in the halfway house and Henry who had come from a timber camp where he had been taught to go through obscene pantomimes to amuse the woodcutters are prime examples. Even more surprising is a record of Joan's irrational attack on a favorite ranger, which was thought to be a reflection of life among human beings rather than of the orangutan's natural character.

Most wild orangutans would have made frightening threat 255 displays by snatching up branches, bellowing, or stamping the ground but they would not have attacked {Mydans 1973:

32) .

Another interesting aspect of the rehabilitation project is the contact between the project animals and their wild companions. Some of the encounters lead to physical contacts, usually with the largest male in the area and unless the male indulges in an impressive display, the encounters are generally very smooth. As Rijksen points out, many of the orangutans being rehabilitated, when they enter the station, have never before in their lives climbed trees or seen other orangutans, apart from their mothers, from whom they had been taken in infancy. It is very rewarding to see mentally depressed and nasty, biting animals change after a few days of freedom and become playful and friendly (Rijksen 1974:24).

Reviewing the entire program from a less optimistic angle, one must admit that while some orangutans run away

from the rehabilitation center and never return (which means that they have been re-orangutanized) others are not nearly

so successful. In fact, some orangutans die, perhaps from the trauma of having to live between two cultures "ours and

their own" . Others simply want to keep hanging around the

center waiting for mealtimes and playing with the wardens, which indicates that it is easier to create dependents than

to make dependents independent once again (Kann 1972:2).

But, in the ultimate analysis, we must point out that many 256 orangutans are reintroduced successfully to the wild and this is an eloquent tribute to the splendid work done at the rehabilitation centers. To end on a note of mild scepticism, however, one cannot help but conjecture what effect the introduction of a large number of rehabilitated orangutans with a rather developed pattern of social behavior will have on the behavior of the wild orangutans in the vicinity of the rehabilitation center (Rijksen 1974;

24). It is hoped that this experiment will not inadvertently lead to the gradual "de-orangutanizing" of the entire species. Chapter 7

DISCUSSION AND FUTURE CONSIDERATIONS

CONCLUSION

Through lack of planning, lack of knowledge and inconsistency of methods, no remarkable breakthrough in cage adjustment can be attributed to the hand-rearing experiment of the orangutan twins. In fact, after all the problems, conflicts and work it took to carry out such a project, the twins adjusted much in the same manner as they would have had they been hand-reared in a human family as humans and then placed in the cage. It would appear that the prime key to successful cage adjustment as well as successful mating, breeding and child rearing lies in réintroduction to the mother and an early cage experience filled with variety, natural foods, exercise equipment and objects designed to stimulate orangutan behavior qualities. Since the orangutan mother was friendly, efforts should have been made toward early réintroduction rather than rearing in isolation to acquaint the twins with isolation in the cage.

Retrospectively, however, when looking back over the progress of the orangutans and the manner in which the program progressed, there are many areas that could have been improved upon which might have made some impact on general health, attitude and adjustment of the twins. After

257 258 studying the literature of primate studies and care, many of which were published after the orangutan project had ended, it is easier to look back and find loopholes in medical care, socialization and general management that marred the project.

The attitude of the zoo was a major problem. Had results of good studies been available, it is doubtful that they would have been considered. This is evidenced by the visit of Barbara Harrisson, an authority on orangutan behavior and founder of the successful rehabilitation centers in Borneo and Sumatra. This person was on a frequent speaking basis with everyone involved in wild-born orangutan observation and rehabilitation as the studies were taking place in her reserves. She was kind enough to advise the zoo on the management of the twins for successful zoo life and breeding programs. The advice came personally in a verbal exchange at a large meeting and, later, in written form in a detailed letter regarding cage introduction.

None of her suggestions were even considered. They all stopped when they reached the level of the Head Ape Keeper.

This self-pride cost Mewar her life by providing her with the very type of rope Dr. Harrisson had cautioned against.

In an analysis of the hand-rearing project, many areas of improvement might be noted for future projects of this type. 259

Isolation

We have seen that partial isolates develop few appropriate social responses and many aspects of abnormal disturbance behavior during the first year of life (Suomi,

Harlow and Kimball 1971:1171). Although rearing animals in partial isolation to acquaint them with cage isolation seems a reasonable thought, it must be remembered that cage isolation was not the ultimate goal. Part of the project was planned to make the twins good breeding and parent candidates as well as good inmates. Therefore, rearing in partial isolation becomes incompatible with the combined goals of the experiment. Since there is an expected increase in non-nutritive orality, the twins should have had pacifiers and bottles of water immediately after birth instead of being allowed to exhibit such long periods of distress and restlessness. Isolated primates are also unmotivated and the twins exhibited this trait throughout the observation period. Regardless of this method of rearing, Harlow and Harlow (1969) found that their rhesus monkeys could overcome this early experience if rehabilitated within a timely period. Three months of isolation left no deficit and six months left residues but twelve months was irreversible. Although the time scale must surely vary for the slower developing orangutan, it appears that if the twins could have gone into a working réintroduction program with their mother at seven months 260 when they left the nursery, they might have been expected to develop a social repertoire compatible with other orangutans.

More of an effort should have been made toward

introducing the twins to the zoo atmosphere rather than just

the isolation aspects. At an early age they might have made

trips to the Small Mammal House and Great Ape House to associate them with scents and noises. Feeding periods

should have been conducted around distractions, perhaps in a cage near the general public. Although children's zoos are

in disfavor with some zoo managers, this is one way to habituate a young animal to the daily crowds and noises that might be expected in adult life.

Maternal Deprivation and Rehabilitation

The plan for hand-rearing Melati and Mewar was to

eliminate any one person as a mother substitute, allowing

the twins to become independent of human relationships.

Barbara Harrisson felt that a plan of this type could be

successful if an effort was made to make the infants feel

secure. In 1941 a study was made of a pair of human

fraternal twins from 36 days of age to age 15 months (Dennis

1941) under conditions of restricted practice and minimum

social stimulation. The aim of the study was to determine

what behavioral development would occur when the care of the

infants was reduced to the minimum attention which would 261 insure their comfort and well-being. No one person acted as a mother substitute but the infants were fed, changed, exercised and given fresh air and sunshine. They were never spoken to, smiled at or played with. At the end of the study, in the opinion of many, the twins were model babies, healthy, happy, active and unspoiled. No behavior could be found to distinguish them from other children of the same age. This contrasts with studies of institutionalized infants (Gray 1951) which show orphaned babies as victims of apathy and emotional disturbances. Unlike the test twins who had comfort and attention but no "mothering", the institutionalized infants did not have attention or comfort.

Melati and Mewar apparently required more attention and stimulation than planned for them because they appeared to be insecure animals. The tantrums appeared to be a request for attention and a direct result of attention directed elsewhere. The fact that the infants insisted on clutching their blankets and having their heads covered indicates the need for some type of satisfaction or comfort not offered. Again, an ideal approach would have allowed the infants to be held and carried often to accustom them to clinging, then reintroduce them to their mother as soon as they could be expected to come to the edge of their cage for feeding.

Since the twins were not reintroduced to their mother as soon as they entered the cage environment but were further deprived by separation from each other, their cage 262 introduction was premature. Barbara Harrisson had advised

cage placement no earlier than nine months of age. Actual plans had been made for cage placement at six months but was delayed somewhat by construction delays. In actuality, cage placement was not done according to the maturity and

adjustment of the twins but for convenience of zoo

schedules. The zoo nursery planned to discontinue its

functions when the orangutans were placed in the cage and

did not want to be responsible for a baby gorilla born when

the twins were five months old. Regardless of the age of

Melati and Mewar, they were placed in the cage at the

earliest time possible. Again, their placement in the cage

of their mother was not planned. Their own cage was needed

for the baby gorilla and there was no other place for the

twins to go. There was no consideration of introducing the

six month old gorilla to the twins as a playmate and

stabilizing factor. Since gorillas develop and mature

faster than orangutans, the young apes would have been

nearly equal at the time of cage introduction for the

gorilla and the gorilla would have had an easier cage

adjustment.

Throughout their first year of life, the twins were

never really prepared for their environment. They were

unstimulated and unaccomplished in problem-solving because

they were not given materials to manipulate or alter. Their

food was always prepared for them and they were never given

the experience of searching for it or peeling it. Their 263 cage environment was totally different from their nursery environment but neither was geared toward building orangutan-like character or even geared toward zoo adjustment.

The goals of the hand-rearing program were independence from humans, cage adjustment, orangutan imprinting, success in breeding programs and daily records of growth and development. Of all these goals, only the last one was positively reached. It is too early to know if any orangutan imprinting was possible or how successful breeding will be. At the end of the study the orangutans, without human socialization or ape socialization, had become withdrawn and cage adjustment had been filled with psychological and physical trauma. However, the fifth goal was reached. The zoo now has records of growth, development, socialization and nutrition if it wishes to hand-rear another infant orangutan in the future. Although the zoo has owned and hand-reared many infant apes, it has never had a record of infancy of any ape before this time.

Perhaps in a future study, the zoo could begin to include a thorough medical profile to make the records complete.

SUGGESTIONS FOR ORANGUTAN REHABILITATION AT NZP AND CURRENT PRIMATE PROGRAMS IN U.S. ZOOS

Due to captive rearing and breeding practices, many mature great apes presently owned by zoos are not psychologically sound. Cage adjustments and improved diet 264 might alter their behavior somewhat but deep rooted social problems still would remain untouched. In order to incorporate these animals into effective breeding programs the artificial methods under which they were reared must be altered to work in the animal's favor. Journals dealing with zoo management and animal behavior are filled with reports of successes and failures of recent experiments in animal maintenance. Besides advice from expert and famous visitors, there are many types of programs which might aid the National Zoological Park in promoting a more liberal attitude toward the care and propagation of its animals.

Programs in Research, Education and Medicine

An experiment that has been announced on television, radio and has been published in some newspapers is being conducted by the Fresno Zoo and, to some extent, the San

Diego Zoo. Since the imitative qualities of apes is well known and since it has been documented that observing social interractions is important in sexual and social development, this experiment plays upon visual assimilation of behavioral factors. Films have been made of courting behavior, copulation, natural birth and handling of infants for ape viewing. These films have only been shown to gorillas and, of course, only gorillas were filmed for this experiment.

Selected pairs of inexperienced gorillas have viewed the films many times and have listened to the appropriate sound effects. The results are still undocumented but it is hoped 265 that this area of communication can open new channels in socialization education.

Advances in sedatives and tranquilizers for veterinary use open another area for successful breeding possibilities. With appropriate drug dosage, the Toledo Zoo was able to breed two incompatible gorillas through reducing aggressiveness and the urge to fight (Hardin, Danford and

Skeldon 1969). Many attempts were made before a suitable means of administering the drug was found but after mixing tranquilizers with honey, matings became much calmer, less violent and after some time, natural enough to be

successful. Some hope is also in store for inexperienced

and nervous zoo mothers. Gandal (1961) was able to

tranquilize a giraffe and a camel who did not permit their

infants to nurse. These "reluctant" mothers were uncomfortable with engorged and edematous udders and

appeared to be too nervous to care for their young. After

administration of a tranquilizer combined with a diuretic to

decrease mammary edema, both mothers allowed brief periods

of nursing. Their udders began to shrink to normal size and

they appeared more relaxed and confident. Both were able to

care for their infants, requiring no further medication.

This type of program might have been ideal for Jennie,

particularly during her last postpartum period when she

mutilated her wrists through nervousness. One problem with

this approach is that an infant often receives residues of a

drug through the breast milk when a mother is under 266 tranquil!zation or sedation but if administration is not prolonged and a mother can begin to act normally enough to act without the drug, then the infant would remain unharmed.

When animals are totally unmanageable in breeding programs, artificial insemination could be considered. The

Zoological Society of London has become concerned enough over the breeding of rare species to plan the establishment of a semen bank (Rowlands 1974). Professor J. Mortelmans and W. Van Den Bergh of Belgium (1969) think artificial insemination would have been the answer to a serious breeding problem they encountered with a rare male bongo.

Since the only chance of breeding the animal was to send it to a female bongo in Cleveland, Ohio, the mating never took place for fear of killing the animal during shipment with anesthesia. That experience initiated the beginning of a program in which sperm can be collected, stored for several years if necessary and then shipped to a zoo in need of breeding a rare animal. When a zoo has only a single representative of a rare animal, there is no other way to breed it. Kai Curry-Lindahl has proposed that research centers in association with zoos and universities should be set up in national parks and game reserves in order to set up central semen banks. This could become a means of simplifying the interchange of breeding lines and make maximum use of breeding potential of new blood obtained from the wild (Jarvis 1965:98). The National Institutes of

Health could be of help to the National Zoological Park in a 267 program of this sort. Some of the zoo's animals are presently under study by NIH and semen samples could be obtained at the time the animals are sedated for their blood tests and medication. Along the same lines, a hormonal imbalance in captivity may render an animal incapable of breeding as well as cause abnormal mating behavior.

Hormones are being used increasingly today by zoos to induce estrus and stimulate the male (Davis 1962:75).

Throughout the United States there has been little formal zookeeper training. Those with experience in laboratories, animal hospitals, farms and pets are among the most knowledgeable employees hired to work as zookeepers.

Most zookeepers have no animal experience and learn about their wards as they care for them on their jobs. A few may take zoology, primatology or courses related to animal husbandry but this is done on their own time and not sponsored by their employers (Giron and Vandiver 1973:265).

Zookeepers with this type of background, unfamiliar with the needs of species under their care, would be misguided when beneficial changes are suggested that might require more attention or more work. If the scheduled physical maintenance of an animal and the cleaning of its cage is the sole job, then a keeper could not be expected to recognize inadequacies in care or environment without studying how specific animals relate to each other and their natural habitat. The Santa Fe Community College in Gainesville,

Florida has initiated a formal training curriculum known as 268 the "Biological Parks Technician Program." This curriculum offers academic credit in areas of animal care as well as park construction and management (Giron and Vandiver 1973:

265-267).

Although all zoos could not be expected to link up with a local university or college for course credits, an effort should be made to conduct mandatory formal classes at the zoo using the animal specialists employed by the zoo as instructors. Surely this type of program would cut down on animal mortality, cage psychosis, malnutrition and a better understanding would evolve concerning breeding and natural rearing. The park in Gainesville, Florida has seen some good results from their program. Students have begun to use imagination in cage expansion, selective feeding, park layout and an awareness of behavior complexity has prompted application of theory to the management of animals.

The National Zoological Park in Washington, D.C. could especially benefit from employee education. Since the zoo is not dependent on public support, but is financed by the government, all employees are under Civil Service.

Many employees tend to remain in their employment for many years because they perform their duties satisfactorily according to their job descriptions and are assured of keeping their jobs. Public suggestions for change have no bearing on employee turnover or job competition. This zoo has no requirements for upgraded education and leave a head zookeeper in each area to carry on the tradition of animal 269 care and teach his employees from his long years of experience. No one at the zoo screens new publications for pertinent information that the zookeepers should know and no mandatory articles are passed along for reading. Although a record of experience is good in animal care, there must also be a combination of theory and recent results of field studies and animal experiments because, in spite of the handling experience, animals are still dying and are still failing to breed and rear their young.

Education of the zoo-going public deserves much thought. Most zoos boast their existence in terms of public education but really seem to miss the point by thinking that merely showing an animal to the public is the ultimate in public education. Phillip Wayre (1969:48) stresses the importance of labelling exhibits with accurate, clear information and Caroline Jarvis (1966:99) carries this thought further by suggesting that labelling always relate to conservation whenever possible. Cleveland Amory, in a book introduction, gives examples of appalling labels he read at the Racine Zoo in Wisconsin:

Under 'Siberian Tiger' the sign reads: 'Usefulness: Pelts for Decorative Purposes.' Under 'African Lion' the sign reads : 'Usefulness : Pelts & Rugs.' Under 'Syrian Brown Bear' the sign was: 'Usefulness: Hide for Rugs, Meat for Food.' Finally, under 'Chimpanzee,' the sign was simply: 'Usefulness: Pets When Young - Zoo and Circus' (Buchenholz 1974:5).

The National Zoological Gardens of South Africa, Pretoria

has allocated special exhibit rooms to teach the importance 270 of conservation to visitors (Smith 1967:184). These exhibits are of the panel type with photographs and printed material. Kai Curry-Lindahl (1966:102) of Sweden finds that some zoos feel conservation and ecology education falls beyond their scope. To this a suggestion is made that a zoo stress the importance of a habitat instead of focusing only on the rare animal. Even though a zoo might not be able to finance breeding research programs, education in the form of lectures, films, classes and exhibits of habitat and animal destruction can help more than simply exhibiting the animals and feeling the job is done. Some zoos even make an effort to invite public participation in handling the animals and assisting in their care. By working with the public, zoos hope that concerned citizens and zoo visitors might be more inclined to finance education programs, more natural facilities for habitation and breeding research programs.

Some zoos have an area set aside for young visitors which is usually called the "Children's Zoo." These small zoos usually exhibit baby animals because they are cute and appealing. The theme of exhibition is often that of fantasy or nursery rhyme or sometimes planned to look like a miniature adult zoo (R.A. Brown 1973:258). Children's zoos have been under attack recently as falling below any pretense of conservation and doing very little toward education of the young. Animals are taken from their natural mothers and bottle-fed daily for public amusement and entertainment. This is one more area left open for 271 future breeding and rearing problems as these animals grow up with a total absence of natural parental care and socialization among their own species. These zoos could be a prime source of education to children by promoting exhibitions aimed at the pre-school and younger school-age children that allow proximity to the animals combined with natural habitat and conservation teaching. Some examples are walk-through aviaries with tame doves that feed from hands and tame wild species handled by a keeper who can answer questions and inform the public. Beehives, egg incubators with hatching chicks and wooded islands with many compatible species living together are successful ventures by some zoos. The Bronx Zoo allows local children to come in to the zoo to feed, clean cages and work with sturdier animals as well as teach the children while they work.

There is also an on-the-job program for high school students who receive wages, school credit and instruction in animal husbandry at the zoo (Smith 1973: 261). With imagination a

zoo can escape a museum-oriented approach, become a working part of the community, provide valuable educational opportunities and maintain a psychologically stable existence for its animals through application of education- related efforts.

Alteration of Zoo Environment

The most successful man-made habitats for primates

are easier to plan in milder climates where controlled 272

temperature is not an engineering consideration. In

Florida, for instance, apes and monkeys are able to be

outdoors for the entire year and forest vegetation grows

readily. Small reserve-like ranches appear to make a good

breeding habitat for rare and endangered species when they

can be located near the geographic range of an endangered

species (Sponsel, Brown, Bailey and Mittermeier 1974) .

While most zoos in the United States are not fortunate

enough to have the climate or the space for a reserve type

of exhibit, many are trying to incorporate features and

circumstances into animal rearing that might parallel some

aspect of natural environment.

The Miami Monkey Jungle has built an Asiatic primate

grotto which is the result of insight, knowledge and

extensive planning. Instead of constructing a living area

for one single species, an interesting and natural

combination of compatible primates co-habit peacefully

together. Orangutans, gibbons and langurs are friendly and

even play with each other while still maintaining their own

boundaries within a small area (DuMond 1970a; 1970b). The

environment makes use of limited space with artificial,

indestructable concrete trees constructed with the enjoyment

of several species in mind. Lower tree structures were

designed for orangutan comfort and higher tree structures

accommodate langurs and gibbons. Since the animals are

active they provide stimulation for each other. Efforts

have been made to leave food hidden about so the animals 273 will have a sense of foraging rather than becoming accustomed to a daily feeding schedule. An obese, senile and unstimulated orangutan received in trade became more active in this program when thyroid extract was administered to increase his appetite and food was placed in areas that required some exertion to obtain it. It was reasoned that a large vegetarian animal would have to negotiate at least one-half mile of jungle each day in search for an adequate supply of food. This amount of exercise would keep an animal in good physical condition and favor an equilibrium between calory intake and energy output. To provide more stimulation and exertion for the orangutan, desired high calory foods such as bananas, apples and monkey chow were placed in small portions at three widely separated stations in the tree network four times a day. Although the orangutan's weight loss was not rapid, he did become strikingly more agile, stimulated and appeared to improve in physical condition. DuMond states in his publication that these ideas are not original but represent how findings of investigators in the field can be applied to local rehabilitation of animals (DuMond 1970a:133).

Under the same director, Goulds Monkey Jungle displays primates in a semi-free-ranging environment. Here, varieties of monkeys live in thick, natural jungles. There are screened walk-throughs so that the public actually enters a monkey habitat rather than monkeys being caged in a human habitat (DuMond 1967). Visitors are allowed to feed 274 the monkeys peanuts through the screen but the monkeys are responsible for obtaining the majority of their food in the depth of the monkey jungle in much the same system practiced in the ape grotto.

Though not in such an elaborate manner, other zoos have also attempted to add variety to the lives of apes and monkeys. The Murrayton Woolly Monkey Sanctuary in Cornwall,

England provides an environment where grubs, moths and various insects can be grown for the monkeys to catch and eat. Sometimes small birds are caught and eaten and raw eggs provide a dietary supplement (Williams 1967:86-87).

Insect diets, including cockroaches, for animals are presently being researched as a natural form of protein

(Tarshis 1961; Lint 1961). The Arnhem Zoo has provided a grove of real trees in which chimpanzees climb and build nests (Van Hoof 1973). In the absence of trees, other zoos have made efforts to entice their apes to climb by constructing split-level living areas or providing hills and placing the visitors at branch level (Sims 1973; Mottershead

1960) .

As previously stressed, the newest recognized problems in zoo management are related to reproduction and care of the young. Some species rarely reproduce successfully in captivity and others are deficient in rearing their young. John Perry and Peter Kibbee of the

National Zoological Park in Washington, D.C. have grave doubts over the practicality of breeding programs in zoos 275

(Perry and Kibbee 1974) . They feel that lack of space in

zoos necessarily prohibits stocking and maintaining a

breeding population of all rare animals exhibited unless

other species are eliminated to make room. They state that

in many instances, there is no outlet for surpluses of rare

animals and zoos fear overcrowding. On the other hand, each

time a member of a rare species dies, the zoo must purchase

a replacement from a dealer or trade with another zoo to

obtain a desired animal. Other concerned directors do not

feel a solution to this problem is very difficult. Many

institutions have suggested that a zoo or laboratory become

specialized in the breeding of one particular species, then

share animals and information with other facilities acting

as a cooperative bank (Lorenz and Mason 1971) . There is

even some thought that breeding surpluses may help

repopulate the wild. At the Chateau de Thoiry, a zoo 25 miles from Paris, fecund lions have produced more than 3 00

offspring since 1967. The cubs are now being exported to a

game reserve back in Africa. Newsweek reports cases of

repopulation of the wild animal kingdom in several areas.

Through zoo breeding, Poland is reintroducing the European

bison, an animal which vanished from its native habitat

centuries ago, to the forests of Poland. The Arabian oryx

has been saved through efforts of zoos in Los Angeles,

Phoenix, London and Abu Dhabi (Newsweek 1975:39). Many zoos

are trying to duplicate wild conditions by opening animal

parks where the animals live in wide open spaces. John 276

Perry of the National Zoological Park states that although commercial safari parks may become a significant breeding resource, they are not recognized by most zoo directors and will continue to be distrusted until they are willing to publish data about their collections (Perry and Kibbee

1974:274). This is an interesting statement coming from a zoo that publishes very little in comparison to other prominent zoos in the United States.

Although many of the newest trends and ideas could be within the range of a zoo like our local one, some commercial pitfalls must be guarded against. One example is the announcement of a new zoo in South Australia (Gasking

1970). This zoo gives one the impression of good intention toward natural animal life and conservation. Large collections of animals roam in enclosures with no barriers between them and zoo visitors. However, after the publication lists the species collected and describes the layout of the grounds, we are then told that some of these animals must be castrated or drugged to reduce aggressive behavior toward human visitors. The Arnhem Zoo chimpanzee consortium found that chimpanzees would destroy trees by peeling off the bark and eating the pith inside the tree.

Electric cylinders were placed around the trees on the outside of the chimpanzee forest so that a chimpanzee would be thrown to the ground as an example to the other chimpanzees as soon as he contacted the electric voltage.

The reason this system was devised was not for the good of 277 the chimpanzees but so the trees would appear attractive for the visitors. Another program at the Children's Zoo in

London aims at stimulating the intelligence of its animals.

Chimpanzees must solve problems in front of the public for their daily food. Although the chimpanzees enjoy showing off and being rewarded with food, nothing has been done to make them more chimpanzee-like and their living quarters are of the standard zoo variety {Morrie 1961). This program is more impractical than practical because it was soon realized that most of the encaged primates were too dangerous to subject to testing and that an extremely large staff would be necessary to deal with the animals and teach them their new tricks. Another problem was the expense of the equipment and thinking up new tricks for the animals to solve to add to their repertoire. Play apparatus and testing equipment left in the cage was quickly destroyed if left unattended. Although this type of program does provide stimulation, it leaves no room for all members of a primate family. Only chimpanzees of a certain age are good candidates for performing and there is no effort to rear the chimpanzees in a natural family atmosphere.

Zoos can no longer afford to remain as institutes of neglected opportunities. Profitable behavioral research can take place in zoological gardens with some planning.

Accurate records must be kept describing all the circumstances related to the animals and studies conducted.

Observations should start at birth and continue throughout 278 life to be correlated with evidence of disease found at death. The scientific validity of research cannot be assessed at an abstract level as observational conditions, health, housing, breeding success and research questions posed all play a part in determining the value of behavioral research conducted in zoos. The closer all physical and social conditions approach that of the typical

natural habitat, except for those being deliberately manipulated for observational or experimental purposes, the more worthwhile the scientific attempt and its application

is likely to be. 279

REFERENCES CITED

Ainsworth, M.D. 1962 The Effects of Maternal Deprivation: A Review of Findings and Controversy in the Context of Research Strategy. Deprivation of Maternal Care : A Reassessment of its Effects. Public Health Papers 14. Geneva: World Health Organization.

19 63 The Development of Infant-Mother Interaction Among the Ganda. ^ Determinants of Infant Behaviour, Vol. 2. B. Foss, Ed. New York: John Wiley and Sons. pp. 67-112.

Allen, R., and B. Gardner 1969 Teaching Sign Language to a Chimpanzee. Science 165:664-672.

Almquist, A.J. 1974 Sexual Differences in the Anterior Dentition in African Primates. American Journal of Physical Anthropology 40:359-368.

Altman, S.A. 1962 The Social Behavior of Anthropoid Primates: An Analysis of Some Recent Concepts. ^ The Roots of Behavior. E.L. Bliss, Ed. New York: Harper and Row. pp. 277-285.

1967 Social Communications Among Primates. Chicago: University of Chicago Press.

Ambrose, J.A. 1961 The Development of the Smiling Response in Early Infancy. ^ Determinants of Infant Behavior. B. Foss, Ed. New York: John Wiley and Sons. pp. 15-3 6.

1963 The Concept of a Critical Period for the Development of Social Responsiveness. ^ Determinants of Infant Behavior, Vol. 2. B. Foss, Ed. New York: John Wiley and Sons.

19 69 Stimulation in Early Infancy. New York: Academic Press.

Andrew, R.J. 1962 Evolution of Intelligence and Vocal Mimicking. Science 137: 585-589.

1963a The Origin and Evolution of the Calls and Facial Expressions of the Primates. Behaviour 20:1-109. 280

1963b Evolution of Facial Expression. Science 142:1034- 1041.

1964 Displays of the Primates. ^ Evolutionary and Genetic Biology of Primates, Vol. 2. J. Buettner, Ed. New York: Academic Press.

Angus, S . 1971 Water-Contact Behavior of Chimpanzees. Folia Primatologies 14:51-58.

Asano, M. 1967 A Note on the Birth and Rearing of an Orangutan (Pongo pygmaeus) at Tama Zoo, Tokyo. International Zoo Yearbook 7:95-96.

Azuma, S., and A. Toyoshima 1962 1961-62 Progress Report of the Survey of Chimpanzees in their Natural Habitat, Kabogo Point Area, Tanzanyika. Primates 3:61-70.

Baldwin, D.B., and S.J. Suomi 1975 Reactions of Infant Monkeys to Social and Nonsocial Stimuli. Folia Primatologica 22: 307-314.

Baldwin, L.A., and G. Teleki 197 3 Field Research on Chimpanzees and Gorillas. Primates 14 : 315-330.

Banks, E. 1949 A Naturalist in Sarawak. Kuching: The Kuching Press

Barnicot, N.A., and C.J. Jolly 1966 Haemoglobin Polymorphism in the Orangutan and an Animal with Four Major Haemoglobins. Nature, London 210:640-642.

Beeson, P.B., and W. McDermott (Eds.) 1967 Cecil-Loeb Textbook of Medicine. Philadelphia: W.B. Saunders.

Bekkum, D.W. van, D. van der Waay, and L.M. van Putten 1969 Need for Specific Pathogen-Free Monkeys in Certain Radiobiological Studies. Annals of the New York Academy of Sciences 162:363-372.

Bergson, G . , and B.A. Ross 1969 Factors to Consider in a Conservation Program for Gibbons. Proceedings of the 2nd International Congress of Primatology, Atlanta, Georgia, 1968. Vol. 1. Karger: Basel. pp. 43-47. 281

Bernstein, I.S. 1961 Response Variability and Rigidity in the Adult Chimpanzee. Journal of Gerontology 16:381-38 6.

1967 Defining the Natural Habitat. ^ Progress in Primatology. D. Starck, R. Schneider, and H.J. Kuhn, Eds. Stuttgart: Gustav Fischer Verlag. pp. 176-179.

1971 Nursery Rearing of Nonhuman Primates Using Poster Mothers. Laboratory Primate Newsletter 10:23-24.

1972 The Organization of Primate Societies: Longitudinal Studies of Captive Groups. ^ The Functional and Evolutionary Biology of Primates. R. Tuttle, Ed. Chicago: Aldin-Ahterton. pp. 399-414.

Beveridge, W.B. 1969 Using Primates in Medical Research. Primates in Medicine, Vol. 3. Karger: Basel. pp. 129-134.

Bingham, L.R., and T.C. Hahn 1975 Observations on the Birth of a Lowland Gorilla (Gorilla g. gorilla) in Captivity. International Zoo Yearbook 14:113-115.

Birch, H. 1945 The Relation of Previous Experience to Insightful Problem-Solving. Journal of Comparative Physiology and Psychology 38: 367-383.

Boelkins, R.C. 1962 Large Scale Rearing of Infant Rhesus Monkeys (Macaca mulatta) in the Laboratory. International Zoo Yearbook 4:285-289.

Booth, C . 1969 Supply of Nonhuman Primates for Medical Research: A Comment. Annals of the New York Academy of Sciences 162:387-389.

Bourne, G.H. 1969 The Chimpanzee. Two Vols. Basel: Karger.

1974 Primate Odyssey. New York: G.P. Putnams' Sons.

Bowlby, J. 19 53 Some Pathological Processes Set in Train by Early Mother-Child Separation. The Journal of Mental Science 99:265-272.

195 8 The Nature of the Child's Tie to His Mother. The International Journal of Psycho-Analysis 39:350-373. 282

1960 Grief and Mourning in Infancy and Early Childhood. The Psychoanalytic Study of the Child 15:9-52.

1961a Separation Anxiety. The International Journal of Psycho-Analysis 41:89-113,

1961b Separation Anxiety: A Critical Review of the Literature. Journal of Child Psychology and Psychiatry 1:251-269.

1969 Attachment and Loss: Volume I Attachment. New York: Basic Books.

1973 Attachment and Loss: Volume II Separation. New York: Basic Books.

Brainard, P.P. 1930 The Mentality of a Child Compared With That of Apes. Journal of Genetic Psychology 37:268-293.

Brandt, E.M., and G. Mitchell 1971 Parturition in Primates; Behavior Related to Birth. In Primate Behavior: Development in Field and Laboratory Research, Vol. 2. L.A. Rosenblum, Ed. New York: Academic Press, pp. 177-225.

Brody, S. 1956 Patterns of Mothering. New York; International Universities Press.

1964 Passivity. New York: International Universities Press.

Brown, C.E. 1930 Birth of a Second Chimpanzee in the Philadelphia Zoological Garden, Journal of Mammology 11: 303-305.

Brown, J . , and W.A. Pieper 1973 Non-nutritive Sucking in Great Ape and Human Newborns. American Journal of Physical Anthropology 38:549-554.

Brown, R.A. 1973 Why Children’s Zoos? International Zoo Yearbook 13:258-261.

Buchenholz, B. 1974 Doctor in the Zoo. New York : Viking Press. 283

Budd, A . , L.G. Smith, and P.W. Shelley 1943 On the Birth and Upbringing of the Female Chimpanzee, "Jaqueline." Proceedings of the Zoological Society of London 113:1-20.

Burlington, Borothy 1952 Twins: A Study of Three Pairs of Identical Twins. New York: International Universities Press.

Buss, D.H., W.R. Voss, and A.H. Nora 1970 A Brief Note on a Modified Formula for Hand-Rearing Infant Baboons. International Zoo Yearbook 10:133-134.

Butler, R.A, 1954 Curiosity in Monkeys. Scientific American 190:70- 75.

Carmichael, L., M.B. Kraus, and T. Reed 1961 The Washington National Zoological Park Gorilla Infant, Tomoko. International Zoo Yearbook 3:88-93.

Carpenter, C.R. 193 8 A Survey of Wildlife Conditions in Atjek of North Sumatra with Special Reference to the Orang-utan. Amsterdam, Netherlands Committee for International Nature Protection. Communications 12:1-34.

1940 A Field Study in Siam of the Behaviour and Social Relations of the Gibbon (Hylobates lar), Comparative Psychology Monographs, Vol. 16.

1964 Naturalistic Behavior of Nonhuman Primates, Pennsylvania State University Press.

Casier, L. 1961 Maternal Deprivation: A Critical Review of the Literature. Monographs of the Society for Research in Child Development, Vol. 26, No. 2, pp. 1-64.

Chaffee, P.S. 1967 A Note on the Breeding of Orangutans (Pongo pygmaeus) at Fresno Zoo. International Zoo Yearbook 7:94-95.

Chamove, A.S. 1973 Rearing Infant Rhesus Together. Behaviour 47:48-66,

1974 A New Primate Social Behaviour Category System. Primates 15:85-99. 284

Chamove, A.S., H.P. Harlow, and G.D. Mitchell 1967 Sex Differences in the Infant-Directed Behavior of Preadolescent Rhesus Monkeys. Child Development 38:329-335.

Chamove, A.S., L.A. Rosenblum, and P.H. Harlow 1973 Monkeys (Macaca mulatta) Raised Only with Peers. A Pilot Study. Animal Behaviour 21:315-325.

Clarke, R.C. 19 34 Notes on the Birth of a Chimpanzee in the Clifton Zoological Gardens, Bristol. Proceedings of the Zoological Society of London 104: 731-732.

Cohen, J.E. 1971 Casual Groups of Monkeys and Men: Stochastic Models of Elemental Social Systems. Cambridge: Harvard University Press.

1975 The Size and Demographic Composition of Social Groups of Wild Orang-Utans. Animal Behaviour 23:54 3-550.

Commission on Professional and Hospital Activities 197 5 Length of Stay in PAS Hospitals, United States, 1974. Ann Arbor, Michigan.

Conant, R. 1974 Philadelphia Zoo Animal Book. Philadelphia, Pennsylvania : Zoological Society of Philadelphia.

Conway, W.G. 1966 The Availability and Long-Term Supply of Primates for Medical Research: A Report on the Conference Held in New York. International Zoo Yearbook 6:284-288.

Cooper, R.W. 1968 Squirrel Monkey Taxonomy and Supply. ^ The Squirrel Monkey. L.A. Rosenblum and R.W. Cooper, Eds. New York: Academic Press, pp. 1-29.

Count, E.W. 1967 The Lactation Complex: A Phylogenetic Consideration of the Mammalian Mother-Child Symbiosis with Special Reference to Man. Homo 18:38-54.

Cousins, Don 1972 Diseases and Injuries in Wild and Captive Gorillas. International Zoo Yearbook 12:211-218.

1975 Classification of Captive Gorillas. International Zoo Yearbook 14:155-159. 285

Cowles, J.T. 1937 Food-Tokens as Incentives for Learning by Chimpanzees. Comparative Psychology Monographs, Vol. 14, No. 5.

Cowles, J.T., and H.W. Nissen 1937 Reward-Expectancy in Delayed Responses of Chimpanzees. Journal of Comparative Psychology.

Crandall, L.S. 196 4 Management of Wild Animals in Captivity. Chicago and London; University of Chicago Press.

Crawford, M.P. 1937 The Cooperative Solving of Problems by Young Chimpanzees. Comparative Psychology Monographs 14:88.

Crawford, M.P., and K.W. Spence 1939 Observational Learning of Discrimination Problems by Chimpanzees. Journal of Comparative Psychology 27:133-147.

Curry-Lindahl, K. 1966 Conservation of Nature - A Duty for Zoological Gardens. International Zoo Yearbook 6:100-102.

Damian, R.T., and E.A. Lichter 1972 Immunological Studies on Chimpanzee Plasma Proteins In Chimpanzee Immunological Specification of Blood. C. Kratochvil, Ed. Primates in Medicine 6:1-67.

Davenport, R.K. 1967 The Orang-utan in Sabah, Folia Primatologica 5:247-263.

Davenport, R.K., and C.M. Rogers 1968 Intellectual Performance of Differentially Reared Chimpanzees: 1. Delayed Response. American Journal of Mental Deficiency 72:67 4-680.

1971 Perception of Photographs by Apes, Behaviour 39:318-320.

Davis, D.D. 1962 Mammals of the Lowland Rain-Forest of North Borneo. Bulletin of the National Museum of Singapore 31:1-129.

Davis, D.G. 1962 Breeding Animals in Zoos. International Zoo Yearbook 4:72-75. 286

Davis, J.H., B.R. McPherson, and J. Moor-Jankowski 1969 Maintenance and Handling of Primate Animals for Medical Research. Annals of the New York Academy of Sciences 162:329-335.

Davis, K. 1940 Extreme Social Isolation of a Child. American Journal of Sociology 45:554-565.

1947 Final Note on a Case of Extreme Isolation. American Journal of Sociology 52:432-437.

Davis, R.T., A.A. McDowell, and H.W. Nissen 1957 Solution of Bent-Wire Problems by Monkeys and Chimpanzees. Journal of Comparative Physiology and Psychology 50:441-444.

Denham, W.W. 1971 Energy. Relations and Some Basic Properties of Primate Social Organization. American Anthropologist 73:77-95.

Dennis, W. 1941 Infant Development Under Conditions of Restricted Practice and Minimum Social Stimulation. Genetic Psychology Monographs 23:143-189.

Derwelis, S.K., J.D. Douglas, J. Fineg, and T.M. Butler 1969 Supply, Maintenance and Handling of Chimpanzees. Annals of the New York Academy of Sciences 162:311-323.

DeSilva, G.S. 1971 Notes of the Orang-utan Rehabilitation Project in Sabah. Malaysian Nature Journal 24:50-77.

1972 The Birth of an Orang-utan (Pongo pygmaeus) at Sepilok Game Reserve. International Zoo Yearbook 12:104-105.

Deutsch, M. 1963 Nursery Education: The Influence of Social Programming on Early Development. Journal of Nursery Education 18:191-197.

DeVore, I. 1963 Problems of Monkey and Ape Behaviour. ^ Classification and Human Evolution. S.L. Washburn, Ed. Viking Fund Publication in Anthropology No. 37. New York: Wenner-Gren Foundation. 287

Dimond, S., and J. Lazarus 1974 The Problem of Vigilance in Animal Life. Brain, Behavior and Evolution 9:60-79.

Dolhinow, P. (Ed.) 1972 Primate Patterns. New York: Holt, Rinehart and Winston.

DuChaillu, P.B. 1861 Explorations and Adventures in Equatorial Africa. New York.

Dumond, F.V. 19 67 Semi-Free-Ranging Colonies of Monkeys at Goulds Monkey Jungle. International Zoo Yearbook 7: 202-207.

1970a New Asiatic Primate Grotto at Miami Monkey Jungle. International Zoo Yearbook 10:43-45.

1970b Notes on Primates in the Asiatic Primate Grotto at Miami Monkey Jungle. International Zoo Yearbook 10:131-133.

Eckhardt, R.B. 1971 Behavioral Adaptability in Free-Ranging Chimpanzees: A Possible Variant Form of Tool Use. Laboratory Primate Newsletter 10:7-10.

19 75 The Relative Body Weights of Bornean and Sumatran Orangutans. American Journal of Physical Anthropology 42:349-350.

Eibl-Eibesfeldt, I. 1968 Ethological Perspectives on Primate Studies. P.C. Jay, Ed. ^ Primates: Studies in Adaptation and Variability. New York: Holt, Rinehart and Winston.

1970 Ethology: The Biology of Behavior. New York: Holt, Rinehart and Winston.

Elder, J.H., and R.M. Yerkes 1936 Chimpanzee Births in Captivity: A Typical Case History and Report of 16 Births. Proceedings of the Royal Society of London, Series B. 120:409-421.

Elftman, H. 1944 The Bipedal Walking of the Chimpanzee. Journal of Mammalogy 25:67-70.

Elkin, F. 1960 The Child and Society ; The Process of Socialization. New York: Random House. 288

Emlen, J.T., and G. Schaller 1960a In the Home of the Mountain Gorilla. ^ Animal Kingdom: Bulletin of the New York Zoological Society 63:98-108.

1960b Distribution and Status of the Mountain Gorilla (Gorilla gorilla beringei) 1959. Zoologica 45:41-52.

Farrer, D.N. 1967 Picture Memory in the Chimpanzee. Perceptual and Motor Skills 25:305-315.

Felce, W. 1948 Apes. London: Chapman and Hall.

Ferster, C.B. 1964 Arithmetic Behavior in Chimpanzees. Scientific American 210:98-106.

Ferster, D.B. , and C.E. Hammer, Jr. 1966 Synthesizing the Components of Arithmetic Behavior: Areas of Research and Application. W.K. Hosig, Ed. New York: Appleton-Century-Crofts. pp. 634-676.

Fiennes, R. 1966 Feeding Animals in Captivity. International Zoo Yearbook 6:58-67.

Fischer, G.J. 1962 The Formation of Learning Sets in Young Gorillas. Journal of Comparative Physiology and Psychology 55:924-925.

Fischer, G.J., and S.L. Kitchner 1965 Comparative Learning in Young Gorillas and Orangutans. Journal of Genetic Psychology 107:337-348.

Fischer, L.E. 1972 The Birth of a Lowland Gorilla at Lincoln Park Zoo, Chicago. International Zoo Yearbook 12:106-108.

Fleming, G. 1972 Go Ape-Speak 'Yerkish'-It Is not Easy, but Primates (Non-Human) are Learning. The NIH Recorder 14:7.

Fletcher, H.J., T.M. Grogg, and J.P. Garske 1968 Ambiguous-Cue Problem Performance of Children, Retardates, and Monkeys. Journal of Comparative Physiological Psychology 66:477-482. 289

Fosberg, R.F. 1969 Sabah (North Borneo), Malaysia; Sepilok Forest Endangered. Biological Conservation 1:339-40.

Foss, B.M. (Ed.) 1969 Determinants of Infant Behaviour IV. London: Methuen, pp. 3-14.

Fossey, D. 1970 Making Friends With the Mountain Gorillas. National Geographic 137:48-67.

1971 More Years With the Mountain Gorillas. National Geographic 140:574.

1972 Vocalizations of the Mountain Gorilla (Gorilla gorilla beringei). Animal Behaviour 20:36-53.

Fox, H. 1929 The Birth of Two Anthropoid Apes. Journal of Mammology 10:37-51.

Freedman, D.G., and N.C. Freedman 1969 Behavioural Differences Between Chinese-American and European-American Newborns. Nature 224:1227.

Freeman, H.E., and J. Alcock 1973 Play Behaviour of a Mixed Group of Juvenile Gorillas and Orang-utans Gorilla gorilla gorilla and Pongo pygmaeus. International Zoo Yearbook 13:189-194.

Freiheit, C.F. 1972 New Primate House at Denver Zoo. International Zoo Yearbook 12:76-77.

Frueh, R. 1968 A Captive Born Gorilla (Gorilla gorilla gorilla) at St. Louis Zoo. International Zoo Yearbook 8:128-131.

Galdikas-Brindamour, B. 1975 Orangutans, Indonesia's "People of the Forest." National Geographic 148:444-472.

Gallop, G.G. 1970 Chimpanzees: Self Recognition. Science 167:86.

Gandal, C.P. 1961 The Use of a Tranquillizer and Diuretic in the Successful Management of Two 'Reluctant Zoo Mothers.' International Zoo Yearbook 3:119-120. 290

Gans, C. 1966 An Inexpensive Arrangement of Movie Camera and Electronic Flash as a Tool in the Study of Animal Behavior. Animal Behaviour 14:11-12.

1969 Modification of an Inexpensive Closed Circuit Television Unit as Adjuncts to Biomechanical Studies. BioScience 19:631.

Gardner, B.T., and R.A. Gardner 1968 How a Young Chimpanzee was Toilet Trained. Laboratory Primate Newsletter 7:1-3.

1969 Teaching Sign Language to a Chimpanzee. Science 169:664-672.

1971 Two Way Communication with an Infant Chimpanzee. In Behaviour of Non Human Primates, Vol. 4. A. Schrier and F. Stollnitz, Eds. New York: Academic Press.

Garner, R.L. 1896 Gorillas and Chimpanzees. London.

Gasking, W.R. 1970 A New 'Zoo' in South Australia. International Zoo Yearbook 10:156-157.

Gavan, J.A. 1953 Growth and Development of the Chimpanzee. Human Biology 25:93-143.

Geddes, H. 1955 Gorilla. London: Melrose.

Gesell, A., and H. Thompson 1929 Learning and Growth in Identical Infant Twins; An Experimental Study by the Method of Co-Twin Control. Genetic Psychology Monograph 6:1-124.

Gijzen, A., and F. Tijskens 19 71 Growth in Weight of the Lowland Gorilla Gorilla gorilla gorilla and the Mountain Gorilla Gorilla gorilla beringei. International Zoo Yearbook 11:183-193.

Giron, R.E., and M.M. Vandiver 1973 A Keeper Training Programme - One Approach. International Zoo Yearbook 13:265-267.

Glickman, S.E., and R.W. Sroges 1966 Curiosity in Zoo Animals. Behaviour 26 :151-189. 291

Golding, R.R, 1972 A Gorilla and Chimpanzee Exhibit at the University of Ibadan Zoo. International Zoo Yearbook 12:71-76.

Goldsmith, E.I. 196 8a Primates Threatened. Nature, London 219:1292.

19 68b Endangered Nonhuman Primates. Science 162:1077.

Goldsmith, E.I., J, Moor-Jankowski, A.S. Wiener, F.H. Allen, and R. Hirsch 1971 Exchange Transfusion of Nonhuman Primates with Human Blood. ^ Medical Primatology, 1970. E.I. Goldsmith and J. Moor-Jankowski, Eds. Karger; Basel.

Goodall, J. 1962 Nest Building Behaviour in the Free Ranging Chimpanzee. Annals of the New York Academy of Sciences 102:455-467.

1963a My Life Among Wild Chimpanzees. National Geographic Magazine. August.

1963b Feeding Behavior of Wild Chimpanzees. ^ The Primates, Symposia of the Zoological Society of London. J, Napier and N.A. Barnicot, Eds. No. 10, pp. 39-48. Zoological Society of London.

19 64 Tool Using and Aimed Throwing in a Community of Free Living Chimpanzees. Nature 201:1264-1266.

1965a. New Discoveries Among Africa's Chimpanzees. National Geographic Magazine. December.

1965b Chimpanzees of the Gombe Stream Reserve. ^ Primate Behavior. I. DeVore, Ed. New York; Holt, Rinehart and Winston.

1967a Mother-Off spring Relationships in Free-Ranging Chimpanzees. ^ Primate Ethology. D. Morris, Ed. Chicago; Aldine Publishing Co. pp. 287-346.

1967b My Friends the Wild Chimpanzees. Washington, D.C. National Geographic Society.

1968a The Behavior of Free-Living Chimpanzees in the Gombe Stream Reserve. Animal Behavior Monograph 1:161-311. 292

1968b A Preliminary Report on Expressive Movements and Communication in the Gombe Stream Chimpanzees. In Primates; Studies in Adaptation and Variability. P.C. Jay, Ed. New York: Holt, Rinehart and Winston, pp. 313-374.

1971 In the Shadow of Man. Boston: Houghton Mifflin.

Goosen, C., T.M. Spelter, and G.A. Boorman 19 72 Chimpanzee Breeding and Pregnancy Diagnosis in the Primate Center TNO. Laboratory Primate Newsletter 11:1-3.

Graham-Jones, O., and W.C.O. Hill 1962 Pregnancy and Parturition in a Bornean Orang. Proceedings of the Zoological Society of London 139:503- 510.

Gray, C.W. 1965 Paraplegia in a Male Lowland Gorilla Gorilla gorilla at the National Zoological Park. International Zoo Yearbook 5:186-189.

Gray, P.H. 1958 Theory and Evidence of Imprinting in Human Infants. Journal of Psychology 46:155-166.

Griffin, G.A., and H.F. Harlow 1966 Effects of Three Months of Total Social Deprivation on Social Adjustment and Learning in the Rhesus Monkey. Child Development 37:533-548.

Groves, Colin P. 1967 Ecology and Taxonomy of the Gorilla. Nature, 211:890-893.

1970 Gorillas. New York: Arco Publishing Company.

Guilloud, N.B. 1969 The Breeding of Apes: Experience at the Yerkes Regional Primate Research Center and a Brief Review of the Literature. Annals of the New York Academy of Sciences 162:297-300.

Guilloud, N.B., and F.L. Fitz-Gerald 1967 Spontaneous Hyperthernia in the Gorilla. Folia Primatologica 6:177-179.

Hafez, E.S.E. (Ed.) 1971 Comparative Reproduction of Laboratory Primates. Springfield, 111.: Thomas. 293

Hall, K.R.L. 1963 Observational Learning in Monkeys and Apes. British Journal of Psychology 54:201-226.

Hamburg, D .A. 1969 Observations of Mother-Infant Interactions in Primate Field Studies. ^ Determinants of Infant Behaviour IV. B.M. Foss, Ed., London: Methuen, pp. 3-14.

Hansen, E.W. 1966 The Development of Material and Infant Behavior in the Rhesus Monkey. Behaviour 27:107-149.

Hardin, C.J., D. Danford, and P.C. Skeldon 1969 Notes on the Successful Breeding by Incompatible Gorillas (Gorilla gorilla gorilla) at Toledo Zoo. International Zoo Yearbook 9:84-88.

Harding, R.S.O., and S.C. Strum 1976 The Predatory Baboons of Kekopey. Natural History March:46-53.

Harlow, H.F. 1949 The Formation of Learning Sets. Psychological Review 56:51-65.

1958 The Nature of Love. American Psychologist 13:673- 685.

1959a Love in Infant Monkeys. Scientific American. June.

1959b Basic Social Capacity of Primates. ^ The Evolution of Mans' Capacity for Culture. J.N. Spuhler, Ed. Detroit: Wayne State University Press.

1959c Affactional Response in the Infant Monkey. Science 130:421-432.

1960 Primary Affectional Patterns in Primates. American Journal of Orthopsychiatry 30:676-684.

1961a Social and Sexual Behavior. Critical Periods of Development: Report on a Conference. Social Science Research Council, Items. 15:16-17.

1961b The Development of Affectional Patterns in Infant Monkeys. ^ Determinants of Infant Behavior. B.M. Foss, Ed. New York: Wiley 75-88.

1962a The Effect of Rearing Conditions on Behavior. Bulletin of the Menninger Clinic 26:213-224. 294

1962b Development of Affection in Primates. ^ Roots of Behavior. E.L. Bliss, Ed. New York: Harper & Brothers.

1963 The Maternal Affectional System. ^ Determinants of Infant Behaviour 2. B. Foss, Ed. New York: John Wiley and Sons. pp. 3-33.

19 65 Total Social Isolation: Effects on Macaque Monkey Behavior. Science 153:148-666.

1966 The Primate Socialization Motives. Transactions and Studies of the College of Physicians of Philadelphia 33:224-237.

1969 Age-Mate or Peer Affectional Systems. ^ Advances in the Study of Behaviour, Vol. 2. D.S. Lehrman, R.A. Hinde, and E. Shaw, Eds. New York: Academic Press.

Harlow, H., and M.K, Harlow 1962 Social Deprivations in Monkeys. Scientific American 207:137-146.

1969 Effects of Various Mother-Infant Relationships on Rhesus Monkey Behaviors. ^ Determinants of Infant Behavior 4. B. Foss, Ed. New York: John Wiley and Sons, pp. 15-36.

Harlow, H.F. , M.K. Harlow, and F.W. Hansen 1963 The Maternal Affectional System of Rhesus Monkeys, In Maternal Behavior in Mammals. H.L. Rheingold, Ed. New York: John Wiley and Sons.

Harlow, H., M.K. Harlow, and S.J. Suomi 1971 From Thought to Therapy: Lessons From a Primate Laboratory. American Scientist 59:538-549.

Harlow, H.F., K.A. Schiltz, and M.K. Harlow 1968 Effects of Social Isolation on the Learning Performance of Rhesus Monkeys. ^ Proceedings of the 2nd International Congress of Primatology, Vol. 1. Basel: Karger. pp. 178-185.

Harris, R.S. (Ed.) 1970 Feeding and Nutrition of Nonhuman Primates. New York: Academic Press.

Harrison, J.L. 1962 The Apes and Monkeys of Malaya (Including the Slow Loris). Popular Pamphlet No. 9, Malayan Museum Pamphlets. Singapore: National Museum. 295

Harrisson, B. 1961 A Study of Orang-utan Behaviour in the Semi-Wild State. International Zoo Yearbook 3:57-68,

1963a Orang-utan. New York; Doubleday.

1963b Education to Wild Living of Young Orang-utans at Bako National Park. Sarawak. Sarawak Museum Journal 11:220-258.

1971 Conservation of Nonhuman Primates in 19 70. Basel: Karger.

1972 Personal Communication to Dr. Nancy Muckenhirn.

Harrisson, T. 1970 The Orang-utan in Sumatra, 1970. Biological Conservation 3:45-46.

Hartwell, W.V., R.D. Kimbrough, and G.J. Love 1968 Serum Transaminase Activities Related to Pathologic Changes of Liver in Chimpanzees. American Journal of Veterinary Research 29:1449-1452.

Hayes, C. 1951 The Ape in Our House. New York: Harper and Brothers,

Hayes, K.J., and C. Hayes 1951 The Intellectual Development of a Home-Raised Chimpanzee. Proceedings of the American Philosophical Society 95:105-109.

1952 Imitation in a Home-Raised Chimpanzee. Journal of Comparative Physiology and Psychology 45:4 50-459.

1953 Picture Perception in a Home-Raised Chimpanzee. Journal of Comparative Physiology and Psychology 46:470- 474.

Hayes, K.J., and R. Thompson 19 53 Nonspatial Delayed Response to Trial-Unique Stimuli in Sophisticated Chimpanzees. Journal of Comparative Physiology and Psychology 46:498-500.

Hayes, K.J., R. Thompson, and C. Hayes 1953 Concurrent Discrimination Learning in Chimpanzees. Journal of Comparative Physiology and Psychology 46:105- 107.

Hediger, H. 1955 Studies of the Psychology and Behaviour of Captive Animals in Zoos and Circuses. New York; Criterion. 296

1964 Wild Animals in Captivity: An Outline of the Biology of Zoological Gardens. New York: Dover.

1966 Diets of Animals in Captivity. International Zoo Yearbook 6:37-58.

Heinicke, C.M., and I.J. Westheimer 1965 Brief Separations. New York; International Universities Press.

Hennessen, W. 1968 A Hemorrhagie Disease Transmitted from Monkeys to Man. National Cancer Institute Monograph 29:161-171.

Herman, C.M. 19 69 The Impact of Disease on Wild Life Populations. BioScience 19:321-330.

Hill, C.A. 1966 Coprophagy in Apes. International Zoo Yearbook 6:251-257.

Hill, W.C. Osman 1938 Observations on a Giant Sumatran Orang. American Journal of Physical Anthropology 24:449-505.

Hinde, R.A. 19 66 Animal Behavior. New York: McGraw Hill.

19 69 Influence of Social Companions and of Temporary Separation on Mother-Infant Relations in Rhesus Monkeys. In Determinants of Infant Behavior IV. B.M. Foss, Ed. London : Methuen.

Hinde, R.A., and Y. Spencer-Booth 19 67 The Behaviour of Socially Living Rhesus Monkeys in Their First Two and a Half Years. Animal Behaviour 15:169-196.

Hinde, R.A., Y. Spencer-Booth, and M. Bruce 1966 Effects of 6 Day Maternal Deprivation on Rhesus Monkey Infants. Nature, London 210:1021-1023.

Hooff, J.A.R.A.M. van 1962 Facial Expressions in Higher Primates. Symposium of the Zoological Society of London 8:97-125.

19 73 The Arnhem Zoo Chimpanzee Consortium: An Attempt to Create an Ecologically and Socially Acceptable Habitat. International Zoo Yearbook 13:195-203. 297

1967 The Care and Management of Captive Chimpanzees with Special Emphasis on the Ecological Aspects. Aeromedical Research Laboratory Technician's Report 67:15.

Hoppe, R. , G. Milton, and E. Simmell (Eds.) 1970 Early Experiences and the Processes of Socialization. New York: Academic Press.

Hornaday, W.T. 1929 Two Years in the Jungle. New York: Charles Scribner's Sons.

Husen, T. 1959 Psychological Twin Research. Stockholm: Almquist and Wiksell.

Imanishi, K. 1960 Social Organization of Sub-Human Primates in Their Natural Habitats. Current Anthropology 1:393-407.

Institute of Laboratory Animal Resources 1968 ILAR News; Summary of Questionnaire to Determine Number of Animals Used for Research in 1968. Vol. 13. pp. j-jx.

International Union for the Conservation of Nature 196 4 Animals and Plants Threatened with Extinction. Survival Service Commission of International Union for the Conservation of Nature.

Itani, J . , and A. Suzuki 1967 The Social Unit of Chimpanzees. Primates 8:355-381.

Izawa, K. 1970 Unit Groups of Chimpanzees and Their Nomadism in the Savannah Woodland. Primates 11:1-46.

Jarrard, L.E. (Ed.) 1971 Cognitive Processes of Nonhuman Primates. New York: Academic Press.

Jarvis, C. 1966 Zoos and Conservation Symposium. International Zoo Yearbook 6:97-99.

1969 Studying Wild Mammals in Captivity: Standard Life Histories with an Appendix on Zoo Records. International Zoo Yearbook 9:316-328. 298

Jay, P.C. (Ed.) 1968 Primates. Studies in Adaptation and Variability. New York: Holt, Rinehart and Winston.

Johnson, R.C. 19 63 Similarity in IQ of Separated Identical Twins as Related to Length of Time Spent in Same Environment. Child Development 34:745-749.

Jolly, A, 197 3 Primate Birth Hour. International Zoo Yearbook 13:391-397.

Jones, C., and J. Sabater Pi 1971 Comparative Ecology of Gorilla gorilla and Pan troglodytes in Rio Muni, West Africa. Bibliotheca Primatologica 13:1-96.

Jones, M.L. 19 62 Mammals in Captivity-Primate Longevity. Laboratory Primate Newsletter 1:3-13.

19 6 8 Longevity of Primates in Captivity. International Zoo Yearbook 8:183-192.

19 74 Mortality of Wild-Caught Animals After Arrival in the Zoo. International Zoo Yearbook 14:37-39.

Jones, N.B. (Ed.) 1972 Ethological Studies of Child Behavior. New York: Cambridge Univ. Press.

Jones, T.S., and A.J.E. Cave 19 60 Diet, Longevity and Dental Disease in the Sierra Leone Chimpanzee. Proceedings of the Zoological Society of London 135:147-155.

Juel-Nielson, N., and B. Harvald 1958 The Electroencephalogram in Uniovular Twins Brought Up Apart. Acta Genetica 8:57-64.

Kagawa, M., and K. Kagawa 1972 Breeding a Lowland Gorilla. International Zoo Yearbook 12:105-106.

Kano, T . 1971 The Chimpanzees of Filabanga, West Tanzania. Primates 12:229-246.

Kaufman, I.e., and L.A. Rosenblum 19 67 Depression in Infant Monkeys Separated from Their Mothers. Science 155:1030-1031. 299

Kawabe, M. 1966 One Observed Case of Hunting Behavior Among Wild Chimpanzees Living in the Savanna Woodland of Western Tanzania. Primates 7:393-396.

Kawai, M., and H. Mizuhara 1959 An Ecological Study of the Wild Mountain Gorilla (Gorilla gorilla beringei) . Primates 2:1-42.

Keeling, M.E., and N.B. Guilloud 1971 Care and Management of a Great Ape Colony. Proceedings of the 2nd Conference on Experimental Medicine and Surgery on Primates, New York, 1969. Basel: Karger. pp. 798-805.

Kellogg, W.N. 1968 Communication and Language in the Home-Raised Chimpanzee. Science 162:423-427.

King, G.E. 1975 Socioterritorial Units Among Carnivores and Early Hominids. Journal of Anthropological Research 31:69-87.

Kirchshofer, R. 1963 The Birth of a Dwarf Chimpanzee, Pan paniscus at Frankfurt Zoo. International Zoo Yearbook 4:76-78.

Kirchschofer, R., K. Berenz, K. Weisse, H. Klose, and I. Klose 196 8 A Preliminary Account of the Physical and Behavioral Development During the First 10 Weeks of the Hand-Reared Gorilla Twins (Gorilla gorilla gorilla) Born at Frankfurt Zoo. International Zoo Yearbook 8:121-128.

Kirchshofer, R., H. Fradick, D. Podolczak, and G. Podolczak 1967 An Account of the Physical and Behavioural Development of the Hand-Reared Infant Gorilla (Gorilla gorilla) Born at Frankfurt Zoo. International Zoo Yearbook 7:108-113.

Knobloch, H., and B. Pasamanick 1959a Gross Motor Behavior in an Infant Gorilla. Journal of Comparative Physiology and Psychology 52:559-563.

1959b The Development of Adaptive Behavior in an Infant Gorilla. Journal of Comparative Physiology and Psychology 52:699-704.

Koch, H.L. 196 6 Twins and Twin Relations. Chicago: University of Chicago Press. 300

Koehler, W, 1925 The Mentality of Apes. London; Routledge and Kegan Paul.

Kozan, K. 1972 Rare Twins at the Zoo Nursery. The Zoogoer 1:3-5.

Koppenfels, H. von 1881 Late Explorations in the Gaboon. American Naturalist 15:447-453.

Kortlandt, A. 1961 Can Lessons From the Wild Improve the Lot of Captive Chimpanzees? International Zoo Yearbook 2:76-80.

1962 Observing Chimpanzees in the Wild. Scientific American 206:128-138.

1965 How Do Chimpanzees Use Weapons When Fighting Leopards? Yearbook of the American Philosophical Society. pp. 327-332.

196 6 Chimpanzee Ecology and Laboratory Management. Laboratory Primate Newsletter 5:1-11.

19 67 Experimentation with Chimpanzees in the Wild. ^ Neue Ergebnisse der Primatologie. D. Starck, R. Schnieder, H.J. Kuhn, Eds. Fischer; Stuttgart, pp. 208- 224.

Kortlandt, A., and M. Kooiz 1963 Protohominoid Behavior in Primates (Preliminary Communication). Symposium of the Zoological Society of London.

Kratochvil, C.H. 1969a Comparative Evaluation of Primates of Medical Research. Annals of the New York Academy of Sciences 162:71-79.

19 69b Anthropoid Apes in Experimental Medicine: A Review. Annals of the New York Academy of Sciences 162:301-310.

Kraus, R.F. 1970 Implications of Recent Developments in Primate Research for Psychiatry. Comprehensive Psychiatry 11:328-335.

Krogman, W.M. 1972 Child Growth. Ann Arbor: Univ. of Michigan Press. 301

Kuininer, H. 1971 Primate Societies. Chicago: Aldine.

Lang, E.M, 1959 The Birth of a Gorilla at Basle Zoo. International Zoo Yearbook 1:3-7.

196 0 Jaitibo, The Second Gorilla Born at Basle Zoo. International Zoo Yearbook 3:84-88,

1962 Goma, The Gorilla Baby. New York: Doubleday and Company.

1966 The Care and Breeding of Anthropoids. ^ Some Recent Developments in Comparative Medicine. E.M. Lang, Ed. New York; Academic Press.

Lapin, B., and E. Friedman 1966 Monkeys for Science. Moscow: Novosti Press Agency Publishing House.

Lasry, J.E., and B.W. Sheridan 1966 Chagas' Myocarditis and Heart Failure in the Red Uakari. International Zoo Yearbook 6:182-184.

Lieberman, P., K.S. Harris, P. Wolf, and L.H. Russell 1971 Newborn Infant Cry and Nonhuman Primate Vocalization. Journal of Speech and Hearing Research 14:718.

Lindburg, D.G., and L.D. Hazell 1972 Licking the Neonate and Duration of Labor in Great Apes and Man. American Anthropologist 74:318-325.

Lindsey, A.A. 196 8 Role of the Individual Ecologist in Natural Area Preservation. BioScience 18: 421-424. Lorenz, K. 1950 The Comparative Method in Studying Innate Behavior Patterns. ^ Physiological Mechanisms in Animal Behavior, Symposium of the Society of Experimental Biology No. 4. New York: Academic Press.

1969 Innate Bases of Learning. ^ On the Biology of Learning. K.H. Prebram, Ed. New York: Harcourt, Brace and World.

Lorenz, R. 1969 Notes on the Care, Diet and Feeding Habits of Goeldi's Monkey. International Zoo Yearbook 9:150-155. 302

Lorenz, R., and W.A. Mason 1971 Establishment of a Colonly of Titi Monkeys Callicebus moloch. International Zoo Yearbook 11:168- 1975.

Lotshaw, R. 1971 Birth of Two Lowland Gorillas (Gorilla gorilla gorilla) at Cincinnati Zoo. International Zoo Yearbook 11:84-87.

Lyght, C.E. (Ed.) 1966 The Merck Manual of Diagnosis and Therapy. New York: Merck Sharp and Dome Research Laboratories.

Lyon, M.W. 1908 Mammals Collected in Eastern Sumatra During 1903, 1906 and 19 07 with Descriptions of New Species and Sub-Species. Proceedings of the United States National Museum 34 : 619-679.

1911 Mammals Collected by Dr. W.L. Abbott on Borneo and Some of the Small Adjacent Islands. Proceedings of the United States National Museum 40:53-146.

MacKinnon, J. 1971 The Orang-utan in Sabah Today. Oryx 11:141-191.

1974a The Behaviour and Ecology of Wild Orang-utans (Pongo pygmaeus). Animal Behaviour 22:3-74.

1974b In Search of the Red Ape. New York: Holt, Rinehart and Winston.

Marlow, D.R., and G . Sellew 1961 Textbook of Pediatric Nursing. Philadelphia: W.B. Saunders.

Martin, R.D. 1975 Strategies of Reproduction. Natural History. November: 48-57.

Mason, W.A. 1963a The Effects of Environmental Restriction on the Social Development of Rhesus Monkeys. ^ Primate Social Behavior. C.F. Southwick, Ed. New York; Van Nostrand, pp. 161-174.

1963b Behavior of Rhesus Monkeys Raised in Isolation. Journal of Psychiatric Research 1:299-306. 303

196 5 Determinants of Social Behaviour in Young Chimpanzees: Cape 9. ^ Behaviour of Non-Human Primates, Vol. 2. A.M. Schrier, H. Harlow, and F. Stollnitz, Eds. New York: Academic Press.

Mason, W.A., and R.R. Sponhoz 1963 Behavior of Rhesus Monkeys Raised in Isolation. Journal of Psychiatric Research 1:299-306.

McCulloch, B . , J. Jonathan, and S.C. Dunnett 1969 Further Report on the Development of Saanane Island and Its Role in Wildlife Conservation in East Africa. International Zoo Yearbook 9:139-142.

McCulloch, T.L. 1939 The Role of Clasping Activity in Adaptive Behaviour of the Infant Chimpanzee. III. Mechanism of Re-Inforcement. Journal of Comparative Psychology 7:305-316.

McNulty, W.P., Jr. (Ed.) 1973 Nonhuman Primates and Human Diseases. Symposia of the Fourth International Congress of Primatology. Portland, Oregon, 1972, Vol. 4. New York: S. Krager.

Meier, G.W. 1965 Other Data on the Effects of Social Isolation During Rearing Upon Adult Reproductive Behavior in the Rhesus Monkey (Macaca mulatta). Animal Behaviour 13:228- 231.

Menzel, E.W. 1963 The Effects of Cumulative Experience on Responses to Novel Objects in Young Isolation-Reared Chimpanzees. Behaviour 21:1-12.

1965 Responsiveness to Object Movement in Young Chimpanzees. Behaviour 24:147-160.

1968 Primate Naturalistic Research and Problems of Early Experience. Developmental Psychobiology 1:175-184.

1972a Spontaneous Invention of Ladders in a Group of Young Chimpanzees. Folia Primatologica 17:87-106.

19 72b Communication About the Environment in a Group of Young chimpanzees. Folia Primatologica 17:220.

Menzel, E.W., Jr., R.K. Davenport, and C.M. Rogers 1970 The Development of Tool Using in Wild-Born and Restriction-Reared Chimpanzees. Folia Primatologica 12:273-283. 304

Miles, P. 1967 Notes on the Rearing and Development of a Hand- Reared Spider Monkey. International Zoo Yearbook 7:82- 85.

Miller, M.J., and R.S. Bray 1966 Entamoeba histolytica Infections in the Chimpanzee (Pan Satyrus). Journal of Parasitology 52:386-388.

Miller-Ben-Shaul, D. 1962 The Composition of the Milk of Wild Animals and Animal Milk Analysis. International Zoo Yearbook 4:332- 342.

1971 Residual Organochlorine Insecticides in the Body Fat of Zoo Animals and in Foods Fed to Zoo Animals. International Zoo Yearbook 11:236-238.

Milton, 0. 1964 The Orang-utan and Rhinoceros in North Sumatra. Oryx 7 :177-184.

Mitchell, G. 1970 Abnormal Behavior in Primates. ^ Primate Behavior, Vol. I. L.A. Rosenblum, Ed. New York: Academic Press, pp. 195-249.

Mitchell, G. , and L. Shroers 1973 Birth Order and Parental Experience in Monkeys and Man. Advances in Child Development and Behavior 8:160- 184.

Moor-Jankowski, J. , and E.I. Goldsmith 1969 The Laboratory for Experimental Medicine and Surgery in Primates. Annals of the New York Academy of Sciences 162:324-328.

Morris, D. 1961 Active Life for Zoo Animals. New Scientist 10:773- 776.

1964 The Response of Animals to a Restricted Environment. Symposium of the Zoological Society of London 13:99-118.

Mortelmans, J. , and W, van den Bergh 1969 Preserved Sperm as a Tool for the Preservation of Rare Mammals. International Zoo Yearbook 9:142-143.

Mottershead, G.S. 1960 Experiments with a Chimpanzee Colony at the Chester Zoo. International Zoo Yearbook 1:18-20. 305

1966 Tropical House at Chester Zoo. International Zoo Yearbook 6:120-123.

Mydans, C. 1973 Orangutans Can Return to the Wild with Some Help. Smithsonian 4:27-33.

Naaktgeboren, C., and E. Slijper 1970 The Biology of Birth. Hamburg: Parey.

Nadler, R.D, 1974 Periparturitional Behavior of a Primiparous Lowland Gorilla. Primates 15:55-73.

Napier, J.R., and P.H. Napier 196 7 A Handbook of Living Primates. London: Academic Press.

Neurauter, L.J. 19 69 Programs and Interests of the NIH in the Use of Nonhuman Primates in Medical Research. Annals of the New York Academy of Sciences 162:378-380.

Newman, H.H, 1940 Multiple Human Births. New York; Doubleday.

Newman, H.H., F.N. Freeman, and K.J. Holzinger 193 7 Twins: A Study of Heredity and Environment. Chicago: University of Chicago Press.

Newsweek 1973 The First Dentist. March 5:73.

1975 Wildlife in Danger. January 6:36-41.

Nishida, T. 1968 The Social Group of Wild Chimpanzees in the Mahali Mountains. Primates 9:167-224.

1970 Social Behavior and Relationship Among Wild Chimpanzees of the Mahali Mountains. Primates 11:47-87.

Nissen, H.W. 1931 A Field Study of the Chimpanzee. Comparative Psychology Monographs 8:1-122.

1956 Individuality in Behaviour of Chimpanzees. American Anthropologist 58:407-413.

Nissen, H.W., J.S. Blum, and R.A. Blum 1948 Analysis of Matching Behavior in Chimpanzees. Journal of Comparative Physiology and Psychology 41:62-74. 306

1949 Conditional Matching Behavior in Chimpanzee; Implications for the Comparative Study of Intelligence. Journal of Comparative Physiology and Psychology 42:339- 356.

Nissen, H.W., and A.H. Riesen 19 45 The Deciduous Teeth of the Chimpanzee. Growth 9:265-274.

1949a Retardation in Onset of Ossification in Chimpanzee Related to Various Environmental and Physiological Factors. Anatomical Record 105:665-675.

1949b Onset of Ossification in the Epiphyses and Short Bones of the Extremities in Chimpanzees. Growth 13:45- 70.

Nissen, H.W., and R.M. Yerkes 194 3 Reproduction in the Chimpanzee: Report on Forty Nine Births. Anatomical Record 86:567-578.

Oberjahann, H. 1957 My Friend the Chimpanzee. London: Robert Hale.

Osborn, R.M. 1963 Behaviour of the Mountain Gorilla. Symposia of the Zoological Society of London 10:29-37.

Oxnard, C.E., and R.H. Tuttle 19 69 An Analysis of the Mechanical Efficiency of the Digital Ray in the Chimpanzee in Relation to Knuckle- Walking Postures and Movement. American Journal of Physical Anthropology 31:265.

Parker, C.E. 1969 Responsiveness, Manipulation, and Implementation in Chimpanzees, Gorillas, and Orangutans. Proceedings of the 2nd International Primatological Society Congress. Karger: Basel. pp. 160-166.

Perry, J . , D.D. Bridgewater, and D.L. Horsemen 1972 Captive Propagation: A Progress Report. Zoologica 57:109-117.

Perry, J , , and P.B. Kibbee 1974 The Capacity of American Zoos. International Zoo Yearbook 14:240-247.

Pfeiffer, J.E. 1972 The Emergency of Man. New York: Harper and Row. 307

Phoenix, C.D. (Ed.) 1973 Primate Reproductive Behavior. Symposia of the Fourth International Congress of Primatology, Portland, Oregon, 19 72, Vol. 2. New York: S. Krager.

Poirier, F.E. (Ed.) 1972 Primate Socialization. New York: Random House.

Poirier, F.E. , and E.O. Smith 1974 Socializing Function of Primate Play. American Zoologist 14:275-289.

Pcurnelle, G.ll. 1965 The Gorilla - Its Status in Captivity. Zoonooz 38:9-10.

Premack, A.J., and D. Premack 1972 Teaching Language to an Ape. Scientific American 227:92.

Premack, D. 1971 Language in Chimpanzees. Science 172:80 8.

Provence, S., and R.C. Lip ton 1962 Infants in Institutions. London: Bailey and Swinfen.

Quiatt, D. (Ed.) 1972 Primates on Primates. Minneapolis: Burgess.

Ratcliffe, H.L. 1966a Diets for Zoological Gardens, Aids to Conservation and Disease Control. International Zoo Yearbook 6:4-23.

19 66b Zoological Gardens: Institutes of Neglected Opportunity. International Zoo Yearbook 6:207-209.

Reed, T., and B.F. Gallagher 1963 Gorilla Birth at National Zoological Park, Washington. Zoologische Garten 27: 279-292.

Reynolds, H.H., C.H. Kratochvil, G.I. Wilson, A.G. Koestler, O.L, Lewis, J.A. Chisum, N.D. Catone, J.A. Tremblay, J.T. Murray, H.G. Steinhauser, and K.H. Schultz 1969 Discussion Paper; Demonstration of Experimental Techniques Using Nonhuman Primates. Annals of the New York Academy of Sciences 162: 381-386.

Reynolds, V. 1968 Kinship and the Family in Monkeys, Apes, and Man. Man 3:209-223. 308

Reynolds, V., and F. Reynolds 1965 The Natural Environment and Behaviour of Chimpanzees Pan troglodytes schweinfurthi, and Suggestions for Their Care in Zoos. International Zoo Yearbook 5:141-145.

Rheingold, H.L. 1961 The Effect of Environmental Simulation Upon Social and Exploratory Behavior in the Human Infant. In Determinants of Infant Behavior I. B.M. Foss, Eds. New York: Wiley and Sons. pp. 143-171.

1963 Controlling Infants Exploratory Behaviour. In Determinants of Infant Behaviour 2. B.M. Foss, Ed. New York: Wiley and Sons.

Rheingold, H., W. Stanley, and J. Cooley 1962 Method for Studying Exploratory Behavior in Infants. Science 136:1054-1055.

Riesen, A.H., and E.F. Kinder 19 52 The Postural Development of Infant Chimpanzees. New Haven, Conn.: Yale Univ. Press.

Riesen, A.H., B. Greenberg, A.S. Granston, and R.L. Fantz 1953 Solutions of Patterned String Problems by Young Gorillas. Journal of Comparative Physiology and Psychology 46:19-22.

Rijksen, H.D. 1974 Orang-utan Conservation and Rehabilitation in Sumatra. Biological Conservation 6:20-25.

Riopelle, A.J. 1963 Growth and Behavioural Changes in Chimpanzees. Zoologica, Morphologica, et Anthropologica 53:53-61.

1972 Learning How Animals Learn. ^ The Marvels of Animal Behavior. Washington, D.C.: National Geographic Society, pp. 358-376.

Robinson, J.S. 1955 The Sameness-Difference Discrimination Problem in Chimpanzees. Journal of Comparative Physiology and Psychology 48:19 5-197.

Rodman, P.S. 1973 Synecology of Bornean Primates. I. A Test for Interspecific Interactions in Spatial Distribution of Five Species. American Journal of Physical Anthropology 38:655-659. 309

Rosenblum, L.A. 1971 Primate Behavior, Vols. 1 and 2. New York: Academic Press.

1972 Sex and Age Differences in Response to Infant Squirrel Monkeys. Brain, Behavior, Evolution 5:30-40.

Rosenblum, L.A., and I.C. Kaufman 1967 Laboratory Observations of Early Mother-Infant Relations in Pigtail and Bonnet Macques. ^ Social Communications Among Primates. S.A. Altman, Ed. Chicago: University of Chicago Press. pp. 33-41.

Roth, T.W. 1969a Primate Supply Today. Proceedings of the 2nd International Congress on Primatology, Atlanta, Georgia, 1968. Vole. 2. Karger: Basel. pp. 206-210.

1969b Supplying Wild Primates to the Laboratory. Primates in Medicine 2:1-16.

Roth, H.H., K.F. Keymer, and B.C. Appleby 1973 Computerized Data Recording for Captive and Free-Living Wild Animals. International Zoo Yearbook 13:252-254.

Rowell, T.E. 19 67 A Quantitative Comparison of the Behavior of a Wild and Caged Baboon Group. Animal Behaviour 15:499-509.

Rowlands, I.W. 1974 Artificial Insemination of Mammals in Captivity. International Zoo Yearbook 14 : 230-233.

Ruch, T.C. 1959 Diseases of Laboratory Primates. Philadelphia; Saunders and Co.

Rumbaugh, D.M. 1965 The Birth of a Lowland Gorilla. Zoonooz 38:12-17.

19 67 "Alvila" San Diego Zoo's Captive Born Gorilla (Gorilla gorilla gorilla). International Zoo Yearbook 7:98-107.

1970 Learning Skills of Anthropoids. Primate Behavior 1:2-70. 310

Rumbaugh, D.M. , and C. McCormack 1967 The Learning Skills of Primates: A Comparative Study of Apes and Monkeys. Iji Progress in Primatology. D. Stark, R. Schneider and H.J. Kuhn, Eds. Fischer: Stuttgart. pp. 289-306.

Rumbaugh, D.M., A.H. Riesen, and S.C. Wright 1972 Creative Responsiveness to Objects: A Report of a Pilot Study with Young Apes. Folia Primatologica 17:397- 403.

Sabater Pi, J. 1967 An Albino Lowland Gorilla from Rio Muni, West Africa, and Notes on its Adaptation in Captivity. Folia Primatologica 7:155-160.

Sade, D.S. 1965 Some Aspects of Parent-Off spring Relations in a Group of Rhesus Monkeys, with a Discussion of Grooming. American Journal of Physical Anthropology 23:1-17. Saenz, A.C. 1969 Diseases in Laboratory Personnel Associated with Vervet Monkeys. I. A General Report on the Outbreak. Primate Medicine 3:129-134.

Salzen, E.A, 1967 Imprinting in Birds and Primates. Behaviour 28:232- 254.

Sasaki, T. 1962 Hand-Rearing a Baby Gibbon. International Zoo Yearbook 4:289-290.

Savoy, J.C. 1965 Tuberculosis in a Zoo Collection of Great Apes. International Zoo Yearbook 5:186-189.

Schaller, G.B. 1961 The Orang-utan in Sarawak. Zoologica 46 :73-82.

1963 The Mountain Gorilla: Ecology and Behaviour. Chicago: University of Chicago Press.

1964 The Year of the Gorilla. University of Chicago Press.

1965 The Behaviour of the Mountain Gorilla. In Primate Behaviour. I. DeVore, Ed. New York: Holt, Rinehart and Winston. 311

Schiller, C.H. 1957 Instinctive Behavior : The Development of a Modem Concept. New York: International Universities Press.

Schiller, P.H. 1952 Innate Constituents of Complex Responses in Primates. Psychological Review 59 :177-191.

Schneirla, T., and J. Rosenblatt 1963 Critical Periods in the Development of Behavior. Science 139:1110-1115.

Schrier, A.M., and F. Stollnitz (Eds.) 1974 Behavior of Nonhuman Primates: Modern Research Trends, Vol. 5. New York: Academic Press.

Schultz, A.H. 193 8 Genital Swelling in the Female Orang-utan. Journal of Mammology 19:363-366.

1941 Growth and Development of the Orang-utan, Contributions to Embryology 29:57-110,

19 56 The Occurrence and Frequency of Pathological and Teratological Conditions and of Twinning Among Nonhuman Primates. Primatologica 1:965-1014.

Schur, M. 1960 Discussion of Dr. John Bowlby's Paper. The Psycho-Analytic Study of the Child 15:63-84.

Schusterman, R.J. 1963 The Use of Strategies in Two-Choice Behavior of Children and Chimpanzees. Journal of Comparative Physiology and Psychology 58:153-156.

Scott, J.P. 1972 Animal Behavior. Chicago; University of Chicago Press.

Seago, John 1974 Responsibilities of an Animal Catcher. International Zoo Yearbook 14:39-40.

Seal, U.S., A. Erickson and J.G. Mayo 1970 Drug Immobilisation of the Carnivora. International Zoo Yearbook 10 :157-159.

Seal, U.S., J. Anderson, R. Farnsworth, and J. Fletcher 1970 Airborne Transport of an Uncaged, Immobilised 260 kg (57 2 lb) Lowland Gorilla. International Zoo Yearbook 10:134-136. 312

Seay, B. 1966 Maternal Behavior in Primiparous and Multiparous Rhesus Monkeys. Folia Primatologica 4:146-169.

Seay, B., B.K. Alexander, and H.F. Harlow 19 64 Maternal Behavior of Socially Deprived Rhesus Monkeys. Journal of Abnormal Social Psychology 69:345.

Seay, B., E. Hansen, and H.F. Harlow 1962 Mother-Infant Separation in Monkeys. Journal of Child Psychology and Psychiatry 3:123-132.

Seitz, A. 19 69 Notes on the Body Weights of Newborn and Young Orang-utans, Pongo pygmaeus. International Zoo Yearbook 9:81-84.

Shields, J. 1962 Monozygotic Twins. London: Oxford University Press.

Shultz, A. 1969 The Life of Primates. New York: Universe.

Simmel, B., and S.M. Coller 1969 Social Facilitation of Exploratory Behavior in Preschool Children. Psychological Record 19:425-430.

Sims, K.J. 1973 Orang-utan Breeding Centre at the Zoo Negara. International Zoo Yearbook 13: 230-232.

Smith, L.J. 19 67 Teaching Conservation in the Zoo. International Zoo Yearbook 7:184.

Southwick, C.H. (Ed.) 1963 Primate Social Behavior. Princeton; Van Nostrand.

Spencer-Booth, Y., and R.A. Hinde 1968 The Behaviour of Group Companions Towards Rhesus Monkey Infants. Animal Behaviour 16: 541-557.

1971 Effects of 6 Days Separation from Mother on 18-32 Week Old Rhesus Monkeys. Animal Behaviour 19:174-191.

Sponsel, L.E., D.S. Brown, R.C. Bailey, and R.A. Mittermeier 1974 Evaluation of Squirrel Monkey Saimiri sciureus Ranching on Santa Sofia Island, Amazonas, Colombia. International Zoo Yearbook 14:233-240. 313

Staley, R.N., and L.J. Green 1974 Types of Tooth Cusp Occurrence Asymmetry in Human Monozygotic and Dizygotic Twins. American Journal of Physical Anthropology 40:187-195.

Stott, K . , and G.J. Selsor 1961 The Orang-utan in N. Borneo. Orxy 5:6.

Stout, C. , P.W. Ogilvie, and W.B. Lemmon 1969 The Correlation of Behaviour and Pathology in Zoo Animals. International Zoo Yearbook 9:197-198.

Suomi, S., and H.F. Harlow 1972 Social Rehabilitation of Isolate Reared Monkeys. Developmental Psychology 6:487.

Suomi, S., H.F. Harlow, and S.D. Kimball 1971 Behavioral Effects of Prolonged Partial Social Isolation in the Rhesus Monkey. Psychological Reports 29:1171.

Suomi, S., H.F. Harlow, and W.T. McKinney 1972 Monkey Psychiatrists. American Journal of Psychiatry 128:927.

Susman, R.L. 1974 Facultative Terrestrial Hand Postures in an Orangutan (Pongo pygmaeus) and Pongid Evolution. American Journal of Physical Anthropology 40:27-37.

Suzuki, A. 19 66 On the Insect-Eating Habits Among Wild Chimpanzees Living in the Savanna Woodland of Western Tanzania. Primates 7: 481-487.

1969a An Ecological Study of Chimpanzees in a Savannah Woodland. Primates 10:103-148.

1969b The Society of Meat-Eating Chimpanzees. Shizen 24:46— 56.

1971a Carnivority and Cannibalism Observed Among Forest Living Chimpanzees. Journal of the Anthropological Society of Nippon 79:30.

1971b On the Problems of Conservation of the Chimpanzees in East Africa and of the Preservation of their Environment. Primates 12:415-418. 314

Tanner, J.M., and B. Inhelder (Eds.) 1971 Discussions on Child Development: A Consideration of the Biological, Psychological and Cultural Approaches to the Understanding of Human Development and Behaviour. New York: International Universities Press.

Tarshis, B.I. 1961 Breeding Cockroaches for Feeding Purposes. International Zoo Yearbook 13:105-107.

Teleki, G. 1973a The Omnivorous Chimpanzee. Scientific American 220:31.

1973b Notes on Chimpanzee Interactions with Small Carnivores in Gombe National Park, Tanzania. Primates 14:407-411.

1973c The Predatory Behavior of Wild Chimpanzees. Lewisburg, Pennsylvania: Bucknell University Press.

Thomas, W.D. 1958 Observations on the Breeding in Captivity of a Pair of Lowland Gorillas. Zoologica 43:95-104.

1969 Great Ape Houses and Grottos at Oraaho Zoo. International Zoo Yearbook 9:62-63.

Thompson, R. 1954 Approach Versus Avoidance in an Ambiguous-Cue Discrimination Problem in Chimpanzees. Journal of Comparative Physiology and Psychology 47:133-135.

Thompson, W.R., and W, Heron 1954 The Effects of Restricting Early Experience on the Problem-Solving Capacities of Primates. Canadian Journal of Psychology 8:17-31.

Tiger, L . , and R. Pox 1971 The Imperial Animal. New York: Holt, Rinehart and Winston.

Trotter, R.J. 1973 I Talk to the Animals. Science News 103:360-361.

Tuttle, R.H. 1967 Knuckle-Walking and the Evolution of Hominoid Hands. American Journal of Physical Anthropology 26:171-206.

1968 Some Swamp Forest Adaptations of the Orangutan. Bulletin of the American Anthropological Association 1:141, 315

1969 The Way Apes Walk. Science Journal. November ; 66.

1972 The Functional and Evolutionary Biology of Primates. Chicago: Aldine Atherton.

Tuttle, R.H., and B.B. Beck 1972 Knuckle Walking Hand Postures in an Orangutan (Pongo pygmaeus) . Nature 236:33-34.

Ulmer, F.A. 1957 Breeding of Orang-utans. Zoologischer Garten 23:57-65.

United States Department of Interior Fish and Game Wildlife Service: Endangered Species Conservation 1970 Notice of Proposed Rule Making. Federal Register 35:6069-6075.

Vandenberg, S.G. 19 66 Contributions of Twin Research to Psychology. Psychological Bulletin 63:327-352.

1968 The Nature and Nurture of Intelligence. ^ Genetics. G. Glass, Ed. New York: Rockefeller University Press.

Vervat. D. 1961 Appendicitis in an Orangutan Pongo pygmaeus at Rotterdam Zoo. International Zoo Yearbook 3:112.

Voronin, L.G. 19 62 Some Results of Comparative Physiological Investigations of Higher Nervous Activity. Psychological Bulletin 59:161-165.

Wackernagel, H . 1966 Feeding Wild Animals in Zoological Gardens. International Zoo Yearbook 6:23-36.

Wayre, P. 1969 The Role of Zoos in Breeding Threatened Species of Mammals and Birds in Captivity. Biological Conservation 2:47-49.

1967 The Role of the Wildlife Park in Nature Conservation. International Zoo Yearbook 7:232-235.

White, B.A. 1929 A Captive Born Chimpanzee. Scientific Monthly 29:558-565. 316

Widmann, F.K. 1973 Goodale's Clinical Interpretation of Laboratory Tests. Philadelphia; F.A. Davis Co.

Williams L. 1967 Breeding Humboldts Woolly Monkey Lagothrix lagotricha at Murrayton Woolly Monkey Sanctuary. International Zoo Yearbook 7:86-89.

Williams, T.R. 1972a The Socialization Process. ^ Primate Socialization. Frank E. Poirier, Ed. New York: Random House. pp. 207-249.

1972b A Socialization Research Strategy; Studies of Isolated Children and Twins. ^ Introduction to Socialization. St. Louis: C.V. Mosby Co. pp. 103-115.

Wilson, W.L. 19 68 Aggressive Interactions of Captive Chimpanzees Living in a Semi-Free Ranging Environment. Report of the 6571st Aeromedical Research Laboratory. Holloman Air Force Base, New Mexico.

World Health Organization 1971 Health Rules for Monkeys and Apes. Division of Public Information. Biological Conservation 3:167-168.

Wrangham, R.W. J.9 74 Artificial Feeding of Chimpanzees and Baboons in their Natural Habitat. Animal Behaviour 22:83-93.

Wright, L. 1961 A Study of Special Ability in Identical Twins. Journal of Genetic Psychology 99:245-251.

Wyatt, J.M., and G.M. Vevers 1935 On the Birth of a Chimpanzee Recently Born in the Society's Gardens. Proceedings of the Zoological Society of London, Series B. 119 :195-197.

Yamamoto, S. 1967 Notes on Hand-Rearing Chimpanzee Twins Pan troglodytes at Kobe Zoo. International Zoo Yearbook 7:97-98.

Yarrow, L.J. 19 61 Maternal Deprivation: Toward an Empirical and Conceptual Re-evaluation. Psychological Bulletin 58:459- 490. 317

Yerkes, R.M. 194 3 Chimpanzees, A Laboratory Colony. New Haven, Conn. Yale University Press.

192 5 Almost Human. New York: Century Company.

Yerkes, R.M., and J.H. Elder 1936 Concerning Reproduction in the Chimpanzee. Yale Journal of Biological Medicine 10:41-48.

Yerkes, R.M., and A.W. Yerkes 1929 The Great Apes. New Haven, Conn.: Yale University Press.

Yoskiba, K. 1964 Report of the Preliminary Survey on the Orang-utan in North Borneo. Primates 5:11-26.