UNIVERSITY OF ILLINOIS
Deceaber 14 1989
Tms IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY
Brenda S. Walters
ENTITLED...... Sociallnttrictionsin ......
••••••(eeeweaeaeevfewfaeeaveeeveelaeeeeeeeeae.,....,*(Mandrlllus sphinx) and...... ,*»«f!.«'....r...... «ea*eee««e*eeeee**es«e*«**e«e*sdVe*«»..Manxabeys (Ctrcocebus atvs) In a Captlvs Ssttina
IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE
DEGREE OF...... B«ch*lor of Arte......
0!«4
N Social Intaraction* in a Mixed Group
of
Mandrills (Mtndrlllm sphinx) and Mangabeys (Cercocebua atya)
In a Captive Setting
By
Brenda S. Walters
Thesis
for the
Degree of Bachelor of Arts
in
Liberal Arts and Sciences
College of Liberal Arts and Sciences
University of Illinois
Urbane, Illinois
1989 TABLE Of CONTENTS
Page
Abstract iii
1.0 Introduction 1
1.1 Mandrills 1
1.2 Sooty Mangabeys 3
2.0 The Setting 4
3.0 The Study Group e
3.1 The Mangabey Group 8
3.2 The Guenon Group 9
3.3 The Mandrill Group 9
3.4 Others 9
3.5 The Focal Group 10
4.0 Method* of Data Collaction 11
5.0 Results 14
5.10 Activity Budget of the Focal Group 14
5.11 Activity Budget of the Adult Male Mandrill 16
5.12 Activity Budget of the Adult Male Mangabey 16
5.13 Activity Budget of Adult Female Mandrill 1 17
i 5.14 Activity Budget of Adult Female Mandrill 2 17
5.15 Activity Budget of the Hybrid 10
5.2 Habitat Use 10
5.3 Measures of Affiliation 20
6.0 Discussion 23
6.1 A Comparison of the Adult Male Mandrill and 23
Mangabey
6.11 Grooming 23
6.12 Spacial Use of Habitat 25
6.13 Agonism 27
6.14 Sexual Behavior 20
6.2 A Comparison of the Adult Female Mandrills 29
6.3 Comparisons Among Adult Mandrills 30
6.4 The Hybrid 31
7.0 Conclusion 32
Appendix At Glossary
Appendix Bt Focal Animals
Appendix C: Habitat Map
Appendix Dt Data Collection Form
Works Cited
ii ABSTRACT
Data were collected on the behavior of a captive group of mandrills (MtndrlllUB BPhlna) and mangabeys (Cercocebus atys)
from July 17, 1969 through August 8, 1989. A total of 33.6 hours of observations were recorded during this time period. Through analysis of individual characteristics and behavior of the animals, interpretation of social interactions will be presented.
Particular focus will be placed on results which reflect differences in sex, reproductive status, and species of the animals.
ill 1.0 INTRODUCTION
Mandrills and sooty mangabeys belong to the family of Old
World monkeys called the Cercopithecidae. Six species of mangabeys are grouped under the genus Cercocebus (Jolly, 1972).
The full taxonomic name for the sooty mangabey is Cercocebus
■tvs■ Mandrills and their close relatives, the drills, have historically been classified under the baboon genus, Paplo. But in recent years a reexamniation of baboon taxonomy has led to a reclassification of the mandrill, subsequently placing it in a separate genus, Mandrillus. This classification is based on a number of genetic and morphological traits which the drill and mandrill share among themselves but not with baboons (Hill, 1970{
Lahm 1986). The mandrill is now refered to as Mandrillus sphinx.
1.1 MANDRILLS
Comparatively little is known about the behavior and ecology of mandrills. This reflects the fact that few field studies have been done on this shy primate which lives in the dense tropical rain forests. Mandrills are subject to high hunting pressures which have reduced their numbers and heightened their fear of humans. A few pioneering studies have been done, but much is left to be discovered about the mandrill.
The mandrill is a large Old World monkey. It exhibits a high degree of sexual dimorphism. Mandrills are sexually dimorphic in
1 2 both sice and coloration, Nalaa weigh on tha average 25 kg, and
females average 11.5 kg (Napier and Napier 1985). Mandrills have
distinctively colored muscles. The nostrils are red, and a red
streak runs up the central portion of the muscle. The streak
flanked by a blue border covering the rest of the muszle. This
type of coloration is seen in both sexes, but it is much brighter
and more prominent among males. Males are colored in much the
same manner in the perineal regicn. This is absent in females.
Mandrills are found in forested areas of Africa in the
Cameroon/Gabon region. Researchers disagree, however, on the
exact extent of the mandrill distribution (Hill, 1970i Hoshino et
al 1984). And whether populations of Mandrillus lauconhasus. the
drill, and Mandrlllus sphinx exist in sympatry, is also debated.
Mandrills are primarily terrestrial animals. They travel and
forage on the densely vegetated floor of the tropical rain forest
(Lahm, 1986). Mrndrills eat a variety of fruits and plants
(Lahm, 1986).
Little is known concerning mandrill social organization.
Mandrills are believed to be organized into uni-male or multi- male units (Stammbach, 1987; Hoshino et al 1984). However, one- male groups are likely the modal pattern in this primate(Stammbach, 1987). Group size has been reported ranging
from 14 to 179 animals (Sabater Pi, 1972).
Much of the information about mandrill biology has been obtained from captive research. Sexual maturity and first reproduction are achieved in approximately 2.5 years (Hadidian 3 and Bernstien 1979). Females display sexual swellings when
receptive. Gestation length is approximately 175 days, and
interbirth intervals average 1.5 years (Hadidian and Bernstein
1979).
1.2 SOOTY MANGABEYS
Nangabeys are smaller and more gracile primates than mandrills. Although they often forage on the ground, mangabeys are primarily arboreal (Bernstein, 1976). These animals too are sexually dimorphic in size, with males weighing approximately twice as much as females.
The distribution of sooty mangabeys ranges from West to
Central Africa (Napier and Napier 1985). Studies have been conducted on these animals in the wild, but studies in captivity are more common. Captive studies have been especially useful in describing the biology of the sooty mangabey.
Sooty mangabeys reach sexual maturity at ages two to three
(Hadidian and Bernstein 1979). Their gestation length is approximately 165 days, and their interbirth interval is between one and two years (Hadidian and Bernstein 1979). Mangabey social organization can be characterized as uni-male or multi male depending on the environment (Bernstein,1976).
Both mandrills and mangabeys have been bred successfully in captive settings. A pattern of uni-male social organization 4 appears to be most effective in captivity, especially in situations where space is limited (King and Mitchell 1987).
The groups examined in this study are uni-male in captivity.
The aim of this study was to examine social interactions among these animals through analysis of quantitative and qualitative data collected on various types of Interactions.
Given this background on the two species, one would expect to find similarities and differences based on biology, ecology, and social organization among them. When examining a mixed species and sex group, differences or similarities might also arise due to individual factors. Through both quantitative and qualitative analysis of koy variables some of the forces which encourage animals to behave in the manner they do can be identified.
2.0 THE SETTING
The study took place at Brookfield Zoo, Brookfield,
Illinois. Brookfield Zoo, along with Lincoln Park Zoo, Lincoln
Park, Illinois, is a member of the Chicago Zoological Society.
The Society is a non-profit organization which supports zoo programs and ethological research in the Chicago area. The
Society has enjoyed appreciable success in its primate breeding program.
Many of the primates at Brookfield Zoo are housed in the 5 largest indoor zoo exhibit in the world, Tropic World. Although
Tropic World features primates, other tropical animals are housed there to create a more realistic ethological mosaic. Tropic
World is divided into three smaller exhibits, reflecting the three major geographic areas in which non-human primates can be found. These exhibits are South America, Asia, and Africa.
Great effort has been taken to reproduce natural surroundings.
The Africa exhibit is divided into two sections, gorilla and monkey. These sections are separated by a net and an artificial cliff structure. On top of the cliff structure is a walkway for zoo patrons. I conducted my study in the African monkey exhibit
(Appendix C).
The monkey half of the Africa exhibit is composed of a series of artificial cliffs skirting its periphery and a number of artificial defoliated trees scattered throughout its central area. The exhibit is bordered on two sides from above by public walkways. One lies to the north and the other, which separates the gorilla and monkey exhibits, lies to the west. The south and east sides of the exhibit are built against the walls of Tropic
World. These slope sharply upwards and contain most of the serried cliffs. The exhibit floor lies approximately fifteen meters below the walkways. Four large artificial trees dominate the center of the exhibit. These are surrounded by 17 smaller trees randomly spaced throughout the habitat. The large central trees branch near the upper third of their length. This places animals on the branches directly in the public's line of sight. 6 The smaller trees also branch at the top, but they are considerably shorter and farther away than the larger ones. Six
"fallen trees" dot the habitat. Stones of various sise and shape are aso found in the exhibit. Most of these are south-centrally placed.
Approximately one fourth of the African monkey exhibit is covered by a shallow layer of water. l tn depth ranges from about one to thirty centimeters. The north side of the habitat on the floor level is a two to three meter broad boundary of water.
This is also true of much of the west side of the habitat. The water in these sections of the exhibit is recirculated through a drainage system and a man-made waterfall. The waterfall lies in the upper southwest corner of the exhibit. Another body of water is found between the four large central trees.
The ceiling of the Africa monkey exhibit is composed of large windows to the north. Artificial lighting is unecessary because these windows provide sufficient light throughout the day for public viewing of the animals. Changes in lighting are noticable at different times of the day and under various weather conditions.
At night the animals are kept in holding cages which lie behind and below the exhibit. In the morning the animals enter the exhibit through a door located in the southeast corner on the cliffs. In the same manner they leave the exhibit in the late afternoon. This doorway is sealed at all other times.
The animals were available for public viewing approximately 7 6.5 hours per day, between the hours of 10s30 a.m. and 5 p.m.
The animals were released into the exhibit shortly before the public was admitted, and they were allowed to return to the holding cages just after the exhibit closed. The animals performed both of these functions without prompting from the staff. They seemed to prefer the exhibit to the smaller holding cages, where they willing returned in the evening to be fed.
The effect of the public on the behavior of the animals appeared to be limited. The waterfall created a high noise level which echoed throughout the spacious exhibit. This blanketed most of the noise created by the public. Visual stimulus was also minimal from the public. Most of the exhibit is located below the public walkways. Photographs requiring a flash are not permitted in Tropic World, although I observed them being taken on more than one occasion. As hard as the public might try, the animals appear disinterested in and unaffected by them. This, of course, is a goal of a zoo, to balance patrons' interests with the animals' best interests. 8 3.0 THE STUDY GROUP
Three genera of Old World monkeys were found In the Africa
exhibit. These were S.grgQ.c.ftbug> CftrcftPlthftfiUg, and Mandrillus.
The common names for these primates are the sooty mangabey
(Cergsgebug atyg), Kolb's guenon (CercapLl.tbggug albagularlg)» and
the mandrill (Mandrillus sphinx). A mandrill-mangabey hybrid was
born at Brookfield and placed in the Africa monkey exhibit. Other
tropical animals were also found in the exhibit. These included
the pygmy hippopotamus (Hippopotamus__iib.ftra.gig) > cattle egret
(Bosluis voael). and the red-billed hornbill (family Bucerotidae)
(Stevenson-Hamilton,1922). The pygmy hippopotamus was confined
to the monkey side of the Africa exhibit, whereas the birds were
free to travel anywhere within the exhibit.
3.1 THE MANGABEY GROUP
The mangabey group on display consisted of nine animals.
Seven of these were female and two were male. One male was an
adult, conspicuosly larger than others in the group, while the
other male was a subadult, indistinguishable in size from most of
the females. The adult male was fifteen years old, and the
subadult was three and one half years old. The females ranged from
four and one half to sixteen and one half years in age* All of these animals were born in captivity. 9
3.2 THE GUENON GROUP
The guenon group was composed of eight animals. Three of
these were male and six were female. Two of the males were larger
than the rest of the guenons. Their ages were five and eight
years. The third male was only one year old. The guenon females
ranged from three to fifteen years old.
3.3 THE MANDRILL GROUP
The mandrills consisted of twelve members, five of which were male and seven of which were female. Their ages ranged from approximately one year to thirteen years. The largest male on exhibit was extremely dimorphic from the rest of the group in both sise and coloration pattern. Like the mangabeys all the mandrills were also born in captivity. The mandril 1-mangabey hybrid was a three year old subadult female.
3.4 OTHERS
Not all of the animals described above were present on the exhibit at the same time. Sometimes it becomes necessary to remove individuals for a number of reasons. During my study all the mangabeys were present as were most of the guenons. But only 10 six mandrills wars seen on the exhibit. Animals not on exhibit were housed in the holding cages. Also, the Zoo has several other species in holding which are periodically rotated in and out of the exhibit. Presently the Zoo is in the process of introducing black and white colobus monkeys (Colobus auereza) into the African monkey exhibit.
3.5 THE FOCAL ANIMALS
Only six animals in the exhibit were chosen as focal subjects due to time limitations involved in the study (See Appendix II).
Familiarity with all the animals could only have been gained through a lengthy preliminary study. Therefore I chose what I believed to be the six most conspicous animals in the exhibit. The guenons were not included as focal animals because the females and subadults were indistinguishable from each other as were the two adult-sized males. The same problem arose with the mangabeys. The females and the subadult male were difficult to individually identify at the onset of the study. But the adult male mangabey was easy to recognize. It was one of the animals I focused on.
The mandrill group displayed the greatest dimorphism. This could be seen between the sexes, age groups, and individuals. Four of the focal animals were chosen from the mandrills. The mandrills included only one adult male. This individual was the most conspicuous animal in the exhibit. It was the largest and most 11 colorful primate. Two adult female mandrills were on exhibit.
Normally these animals might have been difficult to distinguish, but one female had a shaven leg due to recent surgery. It was also much thinner than the other adult female due to this operation.
The adult females were much larger than the subadults and noticeably smaller than the adult male. The fourth focal mandrill was the smallest and youngest member of the mandrill group, a subadult male. This individual seemed to be identifiable a high percentage of the time. But it is possible that it was confused with the other subadults in some instances.
The sixth focal animal I chose was the mangabey-mandrill hybrid. I found this animal easy to identify for a number of reasons. The most pronounced of these was its tail. Mandrills have very short tails while mangabeys have comparatively long tails. The hybrid had an intermediate length tail. It had a mandrill-like facial appearance but a mangabey-sized body. I used more than one characteristic to make a positive identification of this animal.
4.0 METHODS OF DATA COLLECTION
Data were collected over a period of three weeks resulting in
33.6 hours of observation. A total of 1008 observations were recorded on the group and 168 on each focal animal. Data were gathered using an instantaneous time sampling technique. A 12 ' *riety of information was recorded in each observation.
The animals were available for observation between the hours
of 10:30 a.m. and 5 p.m. daily. I divided this basic observation
period into twelve focal sample periods of 28 minutes each. In
this manner each of the six focal animals could be observed twice
a day. Information on a focal animal was gathered at two minute
intervals during the sample period. Use of this instantaneous time
sampling technique facilitated compilation of percentages and
frequencies of data.
The identity of the animal and date of observation was noted
for each focal sample period. Many types of information were
recorded during each observation. The time at which the
observation took place was the first noted. Following this the
location of the focal animal was determined. This involved two
steps. The first was to determine the animals horizontal location
in the exhibit. I divided the African monkey habitat into nine
approximately equal sized horizontal sections (Figure 1). An
animal was always scored as in one of these nine areas. The second
step in locating an animal was to record its vertical level in the
habitat. I divided the height of the exhibit into three layers of
approximately equal height. The branches of all the trees fell
into the uppermost layer.
Special data were also collected in reference to the other
animals in the habitat. After the focal animal was scored in a particular horizontal area, the identity of all other animals in that area was noted. Often I found it difficult to distinguish 13 between individual animals, therefore many of these animals were only identified as to their species. This problem arose in all cases where records of animals other than the focal animals were kept.
The majority of the time one animal was clearly in closer proximity to the focal animal than were the others. This animals' identity was noted in a category termed nearest neighbor. The distance of the nearest neighbor from the focal animal was recorded in four groups. These were zero meters, which was contact, one to five meters, five to ten meters, and more than ten meters.
After these data were collected, the activities of the focal animal were determined. A main activity was recorded in each observation, and in cases where this activty was social, a sub activity was also recorded. Main activities fell into six categories. These were interactions involving the hybrid, intraspecific interactions, interspecific interactions, resting, foraging, and traveling. The first three were classified as social; the last three, asocial. Social interactions always took precedence over asocial interactions. For example, if an animal was chasing another animal, the activity was scored as a social interaction rather than traveling. This made the activities mutually exclusive. I also found the categories to be exhaustive.
Social activities were further divided into six types of sub activities: nursing, agonism, grooming, sexual behavior, huddling, and playing (see Appendix 1). In addition these were labeled contact or non-contact. Next, partners, other animals 14 participating in a social behavior, were noted. Finally
information on the direction of an interaction was gathered.
The length of intervals between observations allowed me to take a number of notes tA libitum. These are not included in the
statistics or tables in this paper, but I found them to be applicable in some aspects of interpretation. In such instances these notes are clearly marked.
5.0 RESULTS
Results of data collection will be presented from the perspective of the focal animal unless otherwise indicated.
Therefore when an observation is said to have occurred N amount of the time, it refers only to the data collected in observation of a particular focal animal.
5.10 ACTIVITY BUDGET OF THE FOCAL GROUP (Table I)
Group main activities broke down as follows: 41.5% resting*
33.2% intraspecific interaction, 9.3% traveling, 8.7% interaction involving the hybrid, 4.2% foraging, and 3.1% interspecific
Interaction. Overall, 45% of main activites were social and 55% asocial. Individual focal animals show both similarities and differences to the group in their activity patterns.
Intraspecific interactions constituted 80.9% of social 15 activities. Interspecific interactions were rare. They accounted
for less than 0.1% of social activities. In approximately 19% of
social activities the hybrid was involved.
Subactivities were recorded only for social interactions. The
most common subactivity was nursing at 40%. Grooming occured 19.1%
of the time. Play activities were recorded 7.1% of the time.
Approximately 11% of subactivities were huddling behavior. 7.0%
involved sexual behavior. Agonism was recorded only 6.6% of the
time.
TABLE Ii GROUP ACTIVITIES
Main Activity______Frequency----%--- GumJS—
Interactions with hybrid 88 8.7 8.7
Intraspecific interactions 335 33.2 42.0
Interspecific interactions 31 3.1 45.0
Resting 418 41.5 86.5
Foraging 42 4.2 90.7
Traveling 94 9.3 100.0
TOTAL 1008 100.0 16
5.11 ACTIVITY BUDGET OF THE ADULT MALE MANDRILL
The adult male mandrill spent 82.7% of the time resting.
Combined with foraging and traveling this created a percentage of
88.7 in asocial activities. Of the remaining 11.3% spent in social activities, 89% were intraspecific The adult male mandrill did not interact with the hybrid during the study, and only twice did it interact with members of another species. In these aspects it diverges from the expected pattern on group frequencies.
Two types of sub-activities were recorded for the adult male mandrill. These were agonism and sexual behavior. Four observations were made of agonism, all of which were non-contact.
Fifteen records were compiled of sexual behavior by the adult male mandrill. Thirteen of these were non-contact, following behavior.
5.12 THE ACTIVITY BUDGET OF THE ADULT MALE MANGABEY
The adult male mangabey's activity budget broke down as follows: 44.6% resting, 36.3% intraspecific interactions, 10.7% interspecific interactions, 5.4% traveling, 2.4% foraging, and
0.6% interactions involving the hybrid. 47.6% of its time was spent in social interactions, while 52.4% was spent asocially.
All subactivities except nursing were recorded for the adult 17 male mangabey. The moat common of these was grooming. Grooming was observed in 68.8% of all of the adult male mangabey's social interactions. Agonism accounted for 22.5% of social interactions. 89% of this agonism was non-contact.
5.13 ACTIVITY BUDGET OF ADULT FEMALE MANDRILL 1
Adult female mandrill 1 interacted with the hybrid on 18 instances. But all of these records were taken when the hybrid was the focal animal. As the focal animal adult female mandrill
1 spent 61.9% of the time resting. 25.6% of its time was spent in intraspecific interactions. The rest of the acitivlty budget was: 9.5% traveling, 1.8% interspecific interactions, and 1.2% foraging. Asocial activities constituted 72.6% of the budget, and social made up 27.4%.
Nursing was a common sub-activity for adult female mandrill
1, at 63.8%. Sexual behavior was next at 19.2%. The remaining sub-activities were less than 10% each.
5.14 ACTIVITY BUDGET OF ADULT FEMALE MANDRILL 2
Observations were not made of adult female mandrill 2 interacting with the hybrid. Also no interspecific interactions were recorded for this animal. 64.9% of its activity budget was spent in intraspecific interactions. Resting accounted for 24.4% of the budget. Traveling occurred B.9% of the time. And less 18 than 2% of the time adult female mandrill 2 was observed foraging. Its budget broke down to 64.9% social and 35.1% asocial. The bulk of subactivities performed by adult female mandrill 2 were nursing at 91.7%. All others were less than 4%.
5.15 ACTIVITY BUDGET OF THE HYBRID
The hybrid was involved in social activities with mandrills and mangabeys during 49.4% of the time. Only one observation was made of a hybrid-guenon interaction. The hybrid spent 19.6% of its time resting, 17.3% traveling, and 13.1% foraging. This totalled 50% social and 50% asocial activities for the hybrid.
The hybrid engaged in huddling, 23.8% of the time, more than any other sub-activity. The hybrid participated in grooming
13.7% of the time and play 10.1% of the time. All other subactivities were performed less than 10% of the time.
5.2 HABITAT USE
Definite trends can be seen in the special use of the habitat by the adult male mandrill and mangabey. The mandrill spent 71.4% of its time in area three, high on the cliffs. The mangabey spent 83.3% of its time in areas four and seven, midway up on the cliffs. In addition the mangabey was never observed in area three, and on only eight occasions the mandrill was seen in area seven. Some overlap occurred in area four. Areas seven and 19 three lie at opposite ends of the exhibit.
The adult female mandrills displayed more liberal use of the habitat than the males, but it still was partially constrained.
Female 2 spent 94.7% of its time in areas one, two, and three.
Likewise, female 1 spent the majority of its time, 60.2%, in the same areas. Areas one, two, and three are located at the back of the exhibit in relation to the walkways.
Of all focal animals, the hybrid showed the most generalized use of the habitat. It spent 44% of the time in area one. All other areas were used 4-11% of the time. It was found near the back of the exhibit a total of 58.3% of the time. 20
T A B U II
HABITAT USE
Araa (£\
0 1 2 3 4 5 6 7 e _ .TOTAL
Focal Animal
Marco(AMD) 23 5 120 6 1 8 5 168
Milt(AMM) 1 5 3 -- 63 11 3 77 5 168
Sapphire(AFDl) 1 44 29 28 36 1 -- 23 6 168
Ruby(AFD2) 1 39 28 92 1 — 5 2 m m mm 168
Kigani(HYBRID) — 74 14 10 20 17 14 7 12 168
TOTAL 3 185 79 250 126 30 22 117 28 840
5.3 MEASURES OF AFFILIATION
An affiliation can ba daacribad aa a relationship Involving fraguant aocial intaractiona and cloaa apaclal proximity bstwaan two or mora animals (Smuts, 1985). As a rasult of data analysis 21 a number of affiliations were found among the study group. The
categories of nearest neighbor, animals in area, and partner were
most useful in determining affiliations.
An adult female mandrill was found to be the nearest
neighbor of the adult male mandrill 85.7% of the time. This
broke down into female 2 as the nearest neighbor 51.2% of the
time and female 1 34.5% of the time. The average distance of
these animals from the adult male mandrill fell in the 1-5 meter
category. The two adult female mandrills were also the animals
that participated in social interactions with the male most
often, at 89.5% of the time. Adult female 1 was the male's
partner in 68.4% of all the male's social activities Adult
female 2 was the partner 21.1% of the time. But due to the
male's low frequency of social activities the latter occurred
only on four occasions. The adult male mangabey completed the
partner category for the adult male mandrill at 10.5%, or two
observations.
The adult male mangabey participated in a higher percentage
of social activities than the adult male mandrill, 47.6%. Its
nearest neighbor in the majority of these was another mangabey at
77.2% of the time. In 54.4% of these observations the nearest neighbor was identified as a female mangabey. The sex of the
remaining 22.8% of the cases was indeterminable. The adult male mangabey's partner in most activities was another mangabey. This occurred 76.3% of the time. The adult male mangabey scored the highest in the interspecific interaction catergory. Eighteen 22 observations were made of interspecific interactions for the adult male mangabey. Fourteen of these were agonistic interactions with an adult male guenon. The adult male mangabey also had the highest frequency of grooming observations, 55.
Nearly all partners involved in this activity were other mangabeys.
Both adult female mandrills interacted most with their subadult offspring. Adult female mandrill l's offspring was its partner 73.9% of the time; and female 2's offspring was its partner 93.6% of the time. The females' offspring were also common nearest neighbors. The adult male mandrill and the offspring were each female l's nearest neighbor 38% of the time.
Female 2's offspring was nearest neighbor in 72.3% of the cases.
The hybrid had the broadest distribution of partners in social interactions. But it was not observed to interact with either adult male in the group or with adult female mandrill 2.
For this animal, social interactions are best clumped into two categories, Interactions with mangabeys and those with mandrills.
It interacted with mangabeys 49.4% of the time and with mandrills
49.5% of the time. Once the hybrid Interacted with a guenon.
The same clumping can be made for the hybrid's nearest neighbor:
58.5% of the time it was a mandrill, and 39.6% of the time it was a mangabey. 23 6.0 DISCUSSION
The results of this study show that individuals diverge from
the group pattern in different types of behavior. These
differences may be due the age, sex, and/or species of the
animal. Comparisons among animals having similiar
characteristics can demonstrate which individual elements account
for these differences.
6.1 A COMPARISON OF THE ADULT MALE MANDRILL AND MANCABEY
These two individuals were identified by a common age status
and sex. In addition they were the only adult males in their
respective species. For these reasons one might predict that
they would also behave similiarly, and if they did not it would
be due to differences between the species. I found this to be
true in some areas but questionable in others.
6.11 GROOMING
The adult males differed greatly in the frequency and type
of social behavior in which they engaged. The adult male
mandrill was not observed in grooming activities, while the adult male mangabey participated in more grooming episodes than any 24 other focal animal. Interestingly, the adult male mangabey was always the recipient of the grooming activity, and the groomer was always another mangabey.
Studies on sooty mangabeys have reported that grooming Is an essential and integral element In maintaining group cohesion
(Ehardt,1988; Bernstein,1976). Adult female mangabeys often prefer to groom the ranking adult male mangabey, even though it does not always reciprocate (Ehardt,1988). Adult female mangabeys also groom each othe^ frequently, but they rarely groom non-kin subadults. I made many ad lib, observations of female- female grooming. The ranking adult male in a group of mangabeys is a central element on which other members focus. Information gathered on grooming in this study tends 1:o support this supposition.
Grooming relationships, as with most social activities in mandrills, are not well known. Captive studies have shown, however, that individual within mandrill groups are less focussed on the high ranking male than are other cercopithecines
(Emory,1975;1977). The data collected during this study concerning social interactions in the mandrill group support this hypothesis. Frequent interaction did not appear to be required in order to maintain group integrity. However, data collected on proximity and habitat use indicate that associations through proximal spacial relationships are common among the mandrills. A possible interpretation of these findings is that similar 25 in ,ual and/or species exhibit preferences for particular
areas.
6.1^ biACIAL USE OF HABITAT
le adult male mandrill and mangabey demonstrated differential habitat use(Table II). Expected frequencies would place the animals in each area an equal number of times. Actual frequencies deviated from this pattern.
The adult male mandrill was found in area three during a significantly high percentage of observations. Area three primarily contained high cliff structures. The mandrill seemed to prefer this area as a resting spot. Other activities occurred outside area three the majority of the time. Adult male mandrills are rarely known to climb trees (Emory, 1975). The height of this area provided an ideal vantage point from which to view the rest of the habitat. The mandrill often sat in the corner of this area. In such a position it could probably detect iitll other animals entering the area.
The adult male mangabey also had a prefered area of the habitat. This was area four, in which it was found most of the time. Area four was adjacent to area seven. The mangabey spent a very high percentage of its time in these two areas combined.
It was most often located on the cliff structures in these areas.
These cliffs were not as high as those found in area three.
These areas were where the adult male spent the greatest amount 26 of time resting.
Areas three and seven are at opposite orners -'f the
exhibit. This may indicate a pattern o. .met beh. /ior between the two adult males. The adult males were never observed to come in direct contact with each other, and rarely were they encountered in the same area simultaneously.
In the wild sooty mangabeys are both arboreal and terrestrial (Napier and Napier 1985). They often feed on the forest floor and sleep in the trees. !rt captivity they have been found to spend most of their time on the ground (Bernstein,
1976). The adult male mangabey was never observed in the trees.
But I made several ad lib, observations of other mangabeys in the trees. Although I did not compile actual frequencies of time spent in trees vs that spent on the ground, I suspect that most of the mangabey group's time was spent in the trees.
Mandrills are among the more terrestrial monkeys (Sabater
Pi,1972). Adult males rarely climb trees, while females and subadults may climb them in order to feed. The mandrills in the study group appeared to follow this pattern. In both focal and ad lib. observations subadulti were often observed climbing and playing in the trees. Although the adult female mandrills were never observed in the trees during a focal period, a few ad lib. observations were made of them in the trees. A possible explanation for this relates to feeding. The animals were fed in the holding cages. The trees did not contain food resources as they might in the wild. Therefore the adult females may have 27 lacked a motivating force to climb the trees. The si\>t iulte
climbed the trees primarily during play activies.
6.13 AGONISM
Agonism was observed most frequently In the adult male mangabey. A total of eighteen agonistic episodes were recorded
for this animal. Of these sixteen were non-contact interactions, and two involved contact. Only four records of agonism were noted for the adult male mandrill. All of these were non- contact. The small sample of agonistic encounters for the adult male mandrill makes identification of patterns difficult. But the mangabey's sample is sufficiently large to begin interpretation of its behavior.
The adult male mangabey acted most aggressively towards the two adult male guenons. Sixteen of the eighteen cases involved one or both of the guenons. Aggression was non-contact in these cases. The adult male guenons might have posed the greatest threat to the mangabey. These animals were often located in areas four and seven in the tree tops. Aggressive episodes between the mangabey and the guenons often began with eye threats from the mangabey. Sooty mangabeys have a light portion of skin above their eyes which they use in communication (Napier and
Napier 1985). The male mangabey raised this portion of its face, and in response the guenons fled. The mangabey chased the guenons as far as the net dividing the habitats where the guenons 28 •scaped to the gorilla exhibit. This was the typical pattern of
aggressive Interactions b e ^ e n these individuals. The remaining
two agonistio interactions of the adult male mangabey involved
contact and members of its own species. Contact agonism took the
form of slapping.
6.14 SEXUAL BEHAVIOR
Sexual behavior, as all sub-acitivities, was separated into contact and non-contact categories. Contact sexual behavior included mounting, attempts to mount, and copulation. Non- contact sexual behavior was following for the assumed purpose of contact sexual behavior.
Only one record of sexual behavior was made for the adult male mangabey. In this episode it mounted adult female mandrill
1. Nine observations were made of sexual behavior in the adult male mandrill. Seven of these involved mounting, and two involved following. Adult female mandrill one seemed to be the prefered partner. It participated in eight of the nine episodes.
Female 1 might have been prefered over female two due to the age of its offspring. Female l's offspring was one and one half years old, and female 2's offspring was approximately one year old. Female 2 spent the majority of its time nursing and avoided direct contact with the adult male mandrill. Female l's offspring was no longer dependent on its mother for food. Female
1 was most likely becoming sexually receptive again. 29
6.2 A COMPARISON OP THE ADULT FEMALE MANDRILLS
Both the differences and similarities between the two adult female mandrills may be explained partially by their reproductive condition and age of their offspring. The females were identical in many aspects, such as: age (13 years), number of offspring (4 each), and sex of offspring (2 male, 2 female). Other than age of most current offspring, the only other major difference I noted between the two was size. Female two had recently lost weight after an operation, and was noticeably thinner than female 1.
The adult female mandrills spent similar amounts of time in areas one, two, and three of the habitat. This placed them in close proximity to the adult male mandrill. These areas seemed to be favorite locations of the females in which they could nurse their offspring. Proximity to the adult male mandrill might have been attractive to the females because the mangabeys seldom used these areas, especially when the male was present.
Nursing was the most common sub-activity in the adult female mandrills. Female 2, which had the younger offspring, participated in nursing more than female 1. This was to be expected due to age of offspring. As discussed earlier, age of offspring probably contributed to mate choice of female 1 more frequently than female 2. Studies of mandrills have found the interbirth interval ranges from 1.5 to 2 years (King and 30 Mitchell, 1987; Stammbach 1987). Female mandrills display
conspicuous sexual swellings around ovulation (Hill, 1970). I
observed this type of characterisec in adult female mandrill 1
for approximately five days at the beginning of my study. Sexual behavior by the adult male mandrill and mangabey occurred during
a portion of this time.
Adult female mandrill 2 participated in social activities with animals other than her youngest offspring less than did
female 1. This may have been the result of time demands placed on it by a younger offspring, or its timidness towards others due to recent reintrodution into the habitat. Female 2 and her offspring had been removed from the habitat for a period of time prior to my study. Upon reintroduction female 2 became the focus of agonistic behavior by some of the animals. Ultimately the decision was made to i-emove the individual which was directing the most aggression towards female 2. This animal was another younger adult female mandrill. The animal had not yet been reintroduced into the habitat at the end of my study.
6.3 COMPARISONS AMONG ADULT MANDRILLS
The most striking similarity among the three adult mandrills was in habitat use. All spent the majority of the time in areas one, two, and three. In addition all seemed to prefer to be in the company of other mandrills. The major differences between these individuals are probably due to sex differences. The 31 females were Involved in a greater number of social interactions due to their offspring.
6.4 THE HYBRID
The hybrid poses an interesting problem. Expected frequencies of behavior 'an be calculated based upon many different factors. One might expect the hybrid to exhibit a suite of behavioral traits intermediate between the two species.
This expectation is based upon the assumption that genetics has strong control over phenotypic manifestations. Another expectation might be that the hybrid would have more traits in common with its mother's species (Cercocebus). because it was raised by its mother. This assumption places importance on environment in development. The data do not strongly support either hypothesis.
The hybrid displayed the most dispersed frequencies of any focal animal. It interacted with mandrills and mangabeys in nearly equivalent frequencies. Here the data appears to support the anetic control hypothesis. Conversely an examination of other animals in the area results in a higher percentage of mangabeys, suggesting that the hybrid prefers to be among members of its mother's species. Finally, some data correlate with neither hypothesis, suoh as habitat use and huddling partners.
These data indicate a preference for the hybrid's father's species, the mandrills. 32
7.0 CONCLUSION
Analysis of data from this study of mandrills and mangabeys
suggests that there are trends in social behavior among the animals. These trends may be due to differences in sex, reproductive status, and/or species. The preceding discussion focussed on the animals which were most likely to demonstrate these trends.
The differences between the adult male mandrill and the adult male mangabey may indicate species differences. The greatest of these appear to be percentage of time spent in social activities and the type of activity in which the animal participates. Comparisons among the mandrills yield results which may be interpreted as exhibiting sex differences.
Discussion of the hybrid was included for purposes of stimulating further thought and study on the subject. Comparisons between the two adult female mandrills are the best case for examining individual differences. Of course, individual differences may have also played a part in the results of the previous two comparisons. It was impossible to control for all variables in this of study. The best way to increase confidence in results is to do more studies.
More studies need to be done on the mangabey and particularly on the mandrill before any concrete conclusions can 33 be mads about thair social organisation. But future studies may not be possible if the decimation of these primate populations is not halted. Mangabeya are activiely captured and traded in some countries, and mandrills continue to be hunted as a prized food source (Rainer and Bourne 1977; Marsh and Mittermeier 1987).
Depopulation may be stopped if practical alternatives are found. APPENDIX A
Adult: Animal which was over four yaars of age. At this stags
in its life it was assumed to be capable of reproduction in
the two focal species. All other animal were labeled
subadult.
Ad lib. sampling: a non-systematic sampling technique in which
the observer subjectively gathers information (Altmann,
1974).
Agonisms aggressive behavior between two individuals.
Agonistic behaviors in this study included biting, slapping,
wrestling, chasing, and threatening through head bobbing and
display of the canines through yawning.
Basic observation period: the in which all animals are observed
equal lenghts of time (Crockett,1989).
Focal animal: individual subject around which lnfromation is
recorded (Altmann, 1974).
Focal group: all focal animals, six in this study.
Focal sample period: length of time in which a focal animal is
continuously observed (Crockett, 1989).
Foraging: Included both eating and drinking. Head bobbingi vertical movement of the head up and down between
the shoulders. This behavior seems to be characteristic
non-contact agonistic behavior of adult male mandrills
(Hill.l970| Bernstein 1970).
Huddling: maintaing body contact with another animal longer than
five seconds without directing any other type of action
trwards it. This behavior was classified as social.
Instantaneous time sampling: "a technique in which the observer
records and individual's current activity at preselected
moments in time" (Altmann, 1974).
Play: most interactions among subadults were classified as play.
This included biting, slapping, chasing, and wrestling.
Resting: this category included observations of autogrooming,
sleeping, and motionless states of an animal which was not
in contact with another. APPENDIX B
Focal Aniraala
Sax Nama _____ Birthdata
Mandrillua aohinx w Ruby 20 April 1976
F Sapphira 26 July 1976
M Ekundu 23 Juna 1988
M Marco 1981*
Carcocabua atva---- N Milt 19 April 1974
Hybrid F Kigani 8 Saptambar 1987
* Exact data of birth not availLbla tPPEMTITY G APPENDIX D ae / / Date H iiim I i !»«nhinx n 2^)9 i « t w o r » 0 x and n i h !"»■« n Nearest l a c o f
g n i l p m a s oa l m i n A Focal WORKS CITED
Altmann, J. 1974. Observational study of behavior. Behavior 49:
227-267.
Bernstein, I. 1970. Some behavioral elements of the
Cercopithecoidaa. In Old World Monheva. New York: Academic
Press, pp. 263-296.
_____, 1976. Activity patterns in a sooty mangabey group. Folia PglBltOiO.fllca.26: 185-206.
Ehardt, C. 1988. Affillative behavior of adult female sooty
mangabeys (Cercocebus atys). Aaerlcin Journal 0£
Prlmatoloav 15: 115-127.
Emory,0. 1975. Comparison of spatial and orientational
relationships as manifestations of divergent modes of social
organisation in captive groups of Mandrillus sphinx and
Theroplthecus qelada. folia JEClBltOlPfllCa .34: 293-314.
_____, 1977. Aspects of attention, orientation, and status
hierarchy in mandrills I '^ndrlllus sphinx) and gelada
baboons (Xhoropitfatcua fly- Uia) • Behavior 59: 7 0 -9 5 .
Hadidian, J., and Bernstein, I. 1984. Old World monkey cycles
and births. Primates 20:429-442.
Hill, W. 1970. Primates. New York: Wiley-Interscience, p.p.
390-490.
Hoshlno, J., Mori, A., Kudo, H., and Kawai, M. 1984. Preliminary
report on the grouping of mandrills. Primates 25:295-307.
King, N., and Mitchell, 0. 1987. Breeding primates in soos. In Behavior. Ed. Mitchell and
Ervin. New Yorks Lias, p.p. 219-261.
Lahrn, S. 1986. Diet and habitat preference of Mandrillua sphinx
in Oabont Implications of foraging strategy. American
Journal of Prlmatoloov lls9-26.
Richard, A. 1985. Primates in Mature. New Yorks H.H. Freeman.
Sabater Pi,J. 1972. Contribution to the ecology of Mandrillua
sphinx Linnaeus 1758 of Rio Muni (Republic of Equitorial
Guinea). Folia Prlmatoloalca 17s 304-319. «**
Smuts, B. 1985. Sex and Friendship in Baboons. Hew Yorks
Aldine.
Stammbach, E. 1987. Desert, forest and Montane baboonss
Multilevel-societies. In Primate Societies. Chicagos
University of Chicago Press, p.p. 112-120.
Stevenson-Hamilton, M. 1922. Animal Life in Africa. New Yorks
E.F. Dutton.