SYSTEMATICS AND BIOGEOGRAPHY OF THE EUTAMIAS OBSCURUS COMPLEX (RODENTIA: SCIURIDAE)

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Authors Callahan, Joan Rea, 1948-

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University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St. John's Road, Tyler's Green High Wycombe, Bucks, England HP10 8HR 77-11,452 CALLAHAN, Joan Rea, 1948- SYSTEMATICS AND BIOGEOGRAPHY OF THE EUTAMIAS OBSCURUS COMPLEX (RODENTIA: SCIURIDAE). The University of Arizona, Ph.D., 1976 Zoology

Xerox University Microfilms, Ann Arbor, Michigan 48106

© 1976

JOAN REA CALLAHAN

ALL RIGHTS RESERVED SYSTEMATICS AND BIOGEOGRAPHY OF THE EUTAMIAS OBSCURUS COMPLEX

(RODENTIA: SCIURIDAE)

by

Joan Rea Callahan

A Dissertation Submitted to the Faculty of the

DEPARTMENT OF GENERAL BIOLOGY

In Partial Fulfillment of the Requirements For the Degree of

DOCTOR OF PHILOSOPHY WITH A MAJOR IN ZOOLOGY

In the Graduate College

THE UNIVERSITY OF ARIZONA

19 7 6

Copyright 1976 Joan Rea Callahan THE UNIVERSITY OF ARIZONA

GRADUATE COLLEGE

I hereby recommend that this dissertation prepared under my

direction by Joan Rea Callahan

entitled Systematics and Biogeography of the Eutamias obscurus

Complex (Rodentla: Sciuridae)

be accepted as fulfilling the dissertation requirement for the decree of Doctor of Philosophy

tr A*gU

As members of the Final Examination Committee, we certify

that we have read this dissertation and agree that it may be

presented for final defense.

wc: mi.

Final approval and acceptance of this dissertation is contingent on the candidate's adequate performance and defense thereof at the final oral examination. !

STATEMENT BY AUTHOR

This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to bor­ rowers under rules of the Library.

Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the copyright holder.

SIGNED: ACKNOWLEDGMENTS

Dr. Russell Davis suggested and encouraged this study. Dr.

Stephen M. Russell and Dr. Oscar G. Ward allowed me to use equipment and laboratory facilities, and Dr. Royal L. Tinsley and Dr. Joan M.

Martin generously provided free translations of German and Russian reference material. Dr. Charles H. Lowe and Dr. Robert 0, Kuehl re­ viewed the manuscript, as did Drs. Davis and Russell. Robert P. Hale executed Fig. 22 and helped me to prepare several other illustrations.

Misty Premovich and Donna Hobbs provided assistance and com­ panionship in the field. A number of lay individuals familiar with a given area or taxon, as well as graduate students and faculty members at various institutions, allowed me to cite their unpublished data or offered various suggestions; each is acknowledged in the text.

The Arizona Department of Game and Fish, the California Depart­ ment of Fish and Game, and the Agencia Forestal y de la Fauna of the

Mexican government authorized me to collect in their respective areas.

The San Mateo County (California) Parks and Recreation Department and the United States Department of the Interior authorized limited col­ lection in certain areas under their jurisdictions.

The United States Public Health Service issued a permit to

Dr. Russell Davis for my use, allowing the importation of live chip­ munks from Mexico. The Mexican consulate in Tucson granted me a gun permit.

iii iv

Partial financial support was provided by my department and

by a grant from the Theodore Roosevelt Memorial Fund of the American

Museum of Natural History. Computer time was provided by the University

of Arizona Computer Center.

The following museum curators allowed me to examine specimens:

Dr. Sydney Anderson, American Museum of Natural History (hereinafter

abbreviated AMNH); Dr. R. R. Clothier, Arizona State University, Depart­

ment of Zoology (ASU); Dr. Robert T. Orr, California Academy of Sciences

(CAS); Ms. Maryann Danielson, Coyote Point Museum, San Mateo, California

(CP); Dr. David G. Huckaby, California State University, Long Beach,

Department of Biology (CSLB): Dr. Robert S. Hoffmann, University of

Kansas, Museum of Natural History (KU); Dr. Donald R. Patten and Dr.

Lan A. Lester, Los Angeles County Museum (LACM); Dr. Jerry R. Choate,

Museum of the High Plains (MHP); Dr. D. P. Christian, Michigan State

University Museum (MSU); Dr. James S. Findley, Museum of Southwestern

Biology (MSB); Dr. Barbara Lawrence, Museum of Comparative Zoology

(MCZ); Dr. William Z. Lidicker, Museum of Vertebrate Zoology (MVZ);

Dr. Charles S. Thaeler, Department of Biology, New Mexico State College

(NMS); Dr. Joseph R. Jehl, San Diego Natural History Museum (SD); Dr.

David J. Schmidly, Texas Cooperative Research Collection, Texas A & M

University (TCRC); Dr. Hugh H. Genoways, The Museum, Texas Tech Univer­

sity (TTM); Dr. E. Lendell Cockrum, University of Arizona, Department

of Ecology and Evolutionary Biology (UA); Dr. James G. Miller, Univer­

sity of California, Los Angeles, Department of Biology (UCLA); and Dr.

Robert D. Fisher, United States National Museum (USNM).

I I i

j i1 ! TABLE OF CONTENTS

Page

LIST OF ILLUSTRATIONS vii

LIST OF TABLES ix

ABSTRACT ; x

1. INTRODUCTION 1

2. MATERIALS AND METHODS 3

Collecting 3 Age Determination 4 Measurement 7 Preparation Techniques 9 Ossa Genitalia ...... 9 Hyoid Bones 9 Karyotypes 9 Spermatozoa 10 Vocalizations ..... 10 Statistical Analysis 10

3. TAXONOMIC CRITERIA 12

Ossa Genitalia 12 Karyology 19 Vocalizations 21 Reproductive Isolation ... 22 The Effect of Environment 24 Other Characters ...... 29 Spermatozoa 29 Sexual Dimorphism 34 Cranial Characters ...... 36 Hyoid Bones 38

4. CHIPMUNKS AS SQUIRRELS 40

Status of Tamias 40 Status of Sciurotamias 45

v vi

TABLE OF CONTENTS—Continued

Page

5. STATUS OF THE GUAYMAS CHIPMUNK POPULATION 52

Eutamias dorsalis sonoriensis, new subspecies .... 54 Description 54 Ecological Notes 61

6. STATUS OF THE EUTAMIAS OBSCURUS COMPLEX 68

Eutamias merriami (Allen, sensu strictu) 70 General Characters 70 Comparisons 71 Geographic Variation 71 Subspecies 78 Eutamias obscurus (Allen) 92 General Characters ... 92 Comparisons 92 Geographic Variation 93 Subspecies 97 Eutamias bulleri (Allen) 119 Co types 119 Topotypes Examined 119 General Characters 120 Comparisons . 120 Distribution 123 Geographic Variation 127 Ecological Notes 127 Eutamias canipes (Bailey) 132

7. DISCUSSION 138

Origin of the Eutamias obscurus Complex ...... 139 Altitudinal Zonation 143

APPENDIX A. SPECIMENS EXAMINED 149

APPENDIX B. MEASUREMENTS 155

LITERATURE CITED 171 LIST OF ILLUSTRATIONS

Figure Page

1. Ossa genitalia of some juvenile (left) and adult Eutamias 6

2. Sonograms of Eutamias sibiricus vocalizations ...... 24

3. Spermatozoa of four Eutamias species 31

4. Spermatozoa of Citellus variegatus .... 33

5. Baubella of Tamias striatus and Eutamias sibiricus .... 43

6. Baubella of Sciurotamias davidianus 49

7. Ossa genitalia of Eutamias dorsalis ...... 55

8. Linear discriminant scores: Eutamias dorsalis sonoriensis (shaded) and JE. _d. dorsalis 57

9. Karyotype of a male Eutamias dorsalis sonoriensis (holo- type; USNM 398643) . 59

10. Distribution of Eutamias dorsalis in Sonora, Mexico .... 60

11. Ossa genitalia of Eutamias merriami . 72

12. Linear discriminant scores: Eutamias merriami merriami, E. m. pricei, and E_. m. kernensls 74

13. Linear discriminant scores: Eutamias obscurus davisi (shaded) and JE. merriami merriami 80

14. Geographic distribution of Eutamias obscurus and E_. merriami 82

15. Ossa genitalia of Eutamias obscurus ...... 93

16. Ossa genitalia of Eutamias speciosus and E_. panamintinus 94

17. Group centroids: Eutamias merriami and E_. obscurus .... 96

18. Karyotypes of Eutamias obscurus 100

vii viii

LIST OF ILLUSTRATIONS—Continued

Figure Page

19. Linear discriminant scores: Eutamias obscurus davisi and E. (>. obscurus 104

20. Anomalous baculum of Eutamias obscurus davisi ...... 107

21. Finding the Peninsula Chipmunk 113

22. Peninsula Chipmunk (Eutamias obscurug meridionalis) nest­ ing in cactus 117

23. Ossa genitalia of Eutamias bulleri 121

24. Karyotypes of two Eutamias species 122

25. Linear discriminant scores: Eutamias bulleri (shaded) and E. canipes durangae 124

26. Distribution of Eutamias bulleri, E. canipes durangae, and IS. dorsalis dorsalis in northwestern Mexico 126

27. Sonograms of Eutamias bulleri arid 15. canipes durangae vo­ calizations 132

28. Bacula of Eutamias quadrivittatus superspecies 135

29. Baubella of Eutamias quadrivittatus superspecies 136

30. Group centroids: Eutamias bulleri and E. canipes 137 LIST OF TABLES

Table Page

1. Bacular characteristics of sympatric and allopatric Euta­ mias species ...... 15

2. Linear discriminant coefficients: Eutamias dorsalis sonori- ensis vs. E. <1. dorsalis 58

3. Common plant species at the type locality of Eutamias dorsalis sonoriensis 62

4. Some common vertebrate species at the type locality of Eutamias dorsalis sonoriensis ...... 63

5. Analysis of variance: tail length of Eutamias merriami . . 76

6. Linear discriminant coefficients: Eutamias merriami merri­ ami vs, E. obscurus davisi 81

7. Analysis of variance: tail length of Eutamias obscurus . . 98

8. Linear discriminant coefficients: Eutamias obscurus davisi vs. 15. obscurus 105

9. Student's t values: Eutamias obscurus meridionalis vs. E_. £. obscurus 112

10. Common plant species associated with Eutamias obscurus meridionalis 114

11. Some common vertebrate species associated with Eutamias ob­ scurus meridionalis 115

12. Linear discriminant coefficients: Eutamias bulleri vs. E_. canipes durangae ...... 125

ix ABSTRACT

Eutamias merriami (Allen) is shown to consist of two parapatric

sibling species: 15. merriami (sensu strictu) and _E, obscurus (Allen).

Because the latter species is endemic to Baja California and adjacent

ranges of southern California, its relationships with chipmunk species of the Mexican mainland are investigated.

The biological significance of each taxonomic character used in

the study is analyzed. The ossa genitalia have considerable taxonomic

value; the baculum appears to provide more information at the species level and the baubellum at higher taxonomic levels. Circumstantial

evidence suggests that the baculum of certain species may be involved with mechanical reproductive isolation.

Chromosomal morphology is relatively uniform below the sub- generic level. The karyotypes of five Mexican chipmunk taxa are presented for the first time.

Vocalizations appear to be involved with reproductive behavior but not with reproductive isolation. There is no clear relationship between vocal behavior and environment; however, the study reveals a higher degree of individual, seasonal, and geographic variability than previous accounts have indicated.

Gross spermatozoan morphology is uniform among four species examined; stages in the maturation of sperm are described. xi

Three patterns of sexual dimorphism and their possible signifi­

cance are discussed.

Certain skull characters are taxonomically useful, particularly

cranial depth, but differences are slight and a multivariate approach

is necessary. Cranial convexity is associated with a tendency toward

arboreality.

These and other characters support the recognition of a single

genus Tamias and three subgenera: Tamias, Eutamias, and Neotamias. The

generic name Eutamias is nevertheless retained in the systematic ac­

counts, because of its general acceptance.

The ossa genitalia of the Chinese rock squirrel Sciurotamias

davidianus are described for the first time. They resemble those of

Tamias, and Sciurotamias is referred to the subtribe Tamiina of the

tribe Marmotini.

Eutamias obscurus is not closely related to IS. dorsalis. A

new subspecies of the latter is described and its habits and affinities

discussed.

IS. obscurus and IS. merriami coexist at several localities in

southern California; range extensions are given. Zones of overlap are

narrow, and there is evidence of competitive exclusion. In the San

Bernardino Mountains IS. obscurus occupies the pinon-juniper belt, below

JS. merriami; in the San Jacinto Mountains it occupies the Transition

life zone, above IS. merriami. The behavior of each species is dis­

cussed, with emphasis on the significance of alarm calls. Elevation

and tail length are negatively correlated in E_. merriami but uncorre­ cted in IS. obscurus. A new subspecies of E. obscurus is described. xii

_E. bulleri (Allen) Is shown also to consist of two parapatric sibling species: 15. bulleri (sensu strictu). including only the former

15. b_. bulleri, and 12. canipes (Bailey). The range of 15, bulleri (s_. s^.) is extended to the northwest by 80 miles. Its vocalizations differ from those of other chipmunks; sonograms are provided. Its baculum resembles that of JE. obscurus, but the two species differ in certain other respects. Within the range of E_. canipes, 15. bulleri apparently is restricted to the arid eastern slope of the Sierra Madre, while 15. canipes occupies more mesic habitats on the western slope. E. bulleri

(s. s_.) is characterized and its habits described. E_, canipes belongs to a complex that requires further taxonomic revision.

The probable origin of the 15. obscurus complex is discussed. A model is proposed to explain the origin of altitudinal zonation in chipmunks. CHAPTER 1

INTRODUCTION

The squirrel ... is a pleasing pretty little domestic: and its tricks and habitudes may serve to entertain a mind unequal to stronger operations.

Oliver Goldsmith, A History of the Earth and Animated Nature (1774)

The original purpose of this study was to investigate possible affinities between a recently discovered Eutamias population in the vicinity of Guaymas, Sonora, and _E. merriami meridionalis, a virtually unknown subspecies believed to breed in the desert ranges of central

Baja California. The geographic relationship of these two populations, taken together with their improbable habitat, small size, and certain other traits, had suggested that they might be conspecific A secondary objective was to resolve conflicting claims regarding the habitat re­ quirements of meridionalis, in view of an apparently universal belief that chipmunks cannot live in the desert.

Neither the existing classification nor my original premise has proven correct. I will show that the chipmunks of Baja California belong to a distinct species, designated here as Eutamias obscurus (Allen) in accordance with the rules of priority; that this species occurs also in southern California; that it is related to the Sierra Madrean E. bulleri;

1 that IS. bulleri itself consists of two species; and that chipmunks do

indeed occur in desert environments.

I will also attempt to reconstruct the evolutionary and bio-

geographic history of the IS. obscurus complex, which arbitrarily in­

cludes E. obscurus, E. merriami, and JE. bulleri (sensu strictu).

Certain other species related to merriami or to bulleri, but less close­ ly related to obscurus, are more briefly considered. One of the two new subspecies described belongs to IS. dorsalis, a species that I have not revised as a whole. The description is included here because the subspecies status of this population was determined in the course of evaluating its relationship to IS. obscurus. CHAPTER 2

MATERIALS AND METHODS

I threw my hat at some individuals to determine their reactions.

Hart (1967)

Collecting

Four summers (1973-1976) were devoted largely to collecting

and field observation in California, Arizona, Nevada, New Mexico, Baja

California, and Durango. I also obtained specimens and/or field data

in Sonora, in November 1973 and November 1974; in Baja California del

Sur in December 1973; and in southern California in October 1973, March

1975, and March 1976. I found it necessary to collect 94 of the approx­

imately 900 specimens assembled for this study, primarily because live

animals were needed for karyotypic analysis and because inadequate

numbers of museum specimens were available from certain critical areas

(e.g., zones of potential intergradation).

The majority of my specimens were collected with a Winchester

.410 shotgun. I used live traps (Havahart, Mustang, and collapsible

Sherman) to obtain animals for karyotypic analysis. Chipmunk popula­

tions vary greatly in their susceptibility to trapping, however, and

during my first visit to Baja California I found meridionalis to be

particularly resistant. Ranchers in the Sierra San Francisco introduced

3 4

me to the following traditional collection method, in exchange for my

Bushnell binoculars.

A long rib of the cardon cactus (Pachycereus pringlei), with a

shorter stick tied at an angle to one end, is inserted into cardon cav­

ities shortly after sunset or before dawn. Such cavities are often used

by chipmunks (Fig. 22, p. 119), which squeak if their nest is disturbed.

When an occupied nest is thus located, the collector blocks the open­

ing with a piece of cloth, climbs the cardon, and uses a machete to hack

off the limb containing the nest. I do not recommend this procedure.

It is interesting to note that wooden tools identical to that

described above were used by Indians in the same mountains during the

14th and 15th centuries A.D., apparently for collecting cactus fruit

(Meighan 1966, 1969). Rock paintings of bipedal figures bearing five longitudinal stripes have also been found there (Meighan 1969:31); comparable figures made by the Hopi Indians of the American Southwest have been identified as chipmunk kachinas (Colton 1949).

Age Determination

Most specimens that I collected were prepared as standard study skins with skulls, and the usual age criterion was the degree of wear on the third upper molar. I was able to distinguish three age classes corresponding to those of Fleharty(1960): juveniles, in which M3 was not fully erupted; subadults, in which it was fully erupted but unworn; and adults, in which it showed considerable wear. A fourth class—old adults, with extremely worn teeth—might be recognized, but these would 5

constitute too small a fraction of any sample for separate comparison.

Statistical comparisons are based on adult (including old adult) speci­ mens only.

By comparing these arbitrary M3 classes with chipmunks of known age (those trapped when visibly immature, and kept in captivity for various periods), I found that the teeth of a typical individual attain the "adult" pattern of wear after the first winter. Beg (1969) provides a detailed account of tooth wear in Eutamias ruf icaudus.

If a specimen lacked M3, age was estimated by the degree of ankylosis of the cranial sutures, by breeding condition if recorded, and by the condition of the hyoid apparatus if present. Fusion of the hypo- hyal and ceratohyal elements of the hyoid is characteristic of adults in the subgenus Neotamias (White 1953a; but see Chapter 4).

Chipmunk ossa genitalia have limited value for age determination, as also noted by White (1953b) and Layne (1954). In young juveniles the os genitale is usually somewhat shorter than in adults, with the basal portion less developed (Fig. la, lb). The baubellum or os clitoris of female juveniles may also be partly cartilaginous (Fig. 1c). But speci­ mens this young are easily recognized as juveniles by body size alone, and in any case the differences are not consistent.

Juveniles differ from adults in pelage texture, but after the first molt the summer pelage of subadults appears very similar to that of adults, at least in the species I have studied. These observations agree with J. A. Allen (1890:50). Fig. 1. Ossa genitalia of some juvenile (left) and adult Eutamias.

All lOx, right lateral view: a, male E. obscurus davisi (UA 23281, 23292). b, female IS. bulleri (MSU 16172, 3332). c, female 12. canipes durangae (USNM 95232, MSU 10274), shaded portion cartilaginous. 7

Tevis (1955) stated that subadult chipmunks can be distinguished from adults in the fall by the degree of development of the lambdoidal

crests, but I have found no consistent age-related differences in this

character.

Measurement

All measurements are expressed in millimeters (mm) unless other­ wise specified.

The external measurements were taken from specimen tags: head and body length (HB), determined by subtraction of tail vertebrae length from total length; tail vertebrae length (TV); length of right hind foot, in­ cluding the longest claw (RHF); and length of right ear from notch (EN).

I did not use any measurement unless the reference points used by the preparator could be determined, either from the tags or from published accounts. Obviously erroneous measurements and those suggesting damage were likewise discarded.

Skulls were measured to the nearest 0.1 mm with a dial caliper, using the following reference points (adapted from Cockrum 1955, Fleharty

1960, and Davis and Schwab 1964).

1. Greatest length of skull (GLS): The overall length from the anterior tips of the nasals to the posterior bulge of the braincase.

2. Rostral length (RL): From the anterior margin of the left orbit to the notch between the anterior tips of the nasals.

3. Length of braincase (LBC): Calculated by subtraction of RL from GLS. j

8

4. Length of maxillary cheek tooth row (MTR): Alveolar distance

from the anterior border of P3 (or PA if P3 absent; see Chapter 4) to

the posterior border of M3.

5. Length of nasals (LN): The greatest length along the suture

between the nasals.

6. Zygomatic breadth (ZB): The greatest distance across the zygo­

matic arches of the cranium perpendicular to the long axis of the skull.

7. Cranial depth (CD): Vertical distance from a line connecting

the tips of the upper incisors with the most ventral portion of the pos­

terior part of the cranium (the auditory bullae or, in some specimens, the

occipital condyles) to the highest part of the cranium; taken by placing

the cranium on a glass slide, measuring from the lower surface of the

slide to the highest point of the skull, and subtracting the thickness of

the slide.

8. Least interorbital breadth (LIB): The least distance across

the top of the skull between the orbits.

9. Cranial breadth (CB): The greatest distance across the brain-

case immediately posterior to the zygomatic arches.

10. Rostral breadth (SB): Taken between the junctures of the

-maxillary and premaxillary bones on either side of the rostrum.

11. Width of nasals (WN): Taken between the junctures of the

premaxillary, frontal, and nasal bones on either side of the rostrum.

The only -measurements of the ossa genitalia that I have used are

total length of baculum (BL), length of baculum shaft (BS), length of

baculum tip (BT), angle formed by baculum shaft and tip (BA), and total length of baubellum or os clitoris (OCL). All five measurements are

self-explanatory; for definitions see Fleharty (1960) and Adams and

Sutton (1968).

Preparation Techniques

Ossa Genitalia

These elements were cleared in 2% KOH for one to five days or

until the surrounding tissues were soft enough to be removed without

damage to the bone. A drop of Alizarin Red S (Hollister 1934) was then

added to the KOH, and after three to four hours any fragments of bone

present were clearly visible. The cleared and stained bones were stored

in 100% glycerin.

Hyoid Bones

These were either air-dried and cleaned by dermestids or cleared and stained in the manner described for the ossa genitalia.

Karyotypes

I used the basic colchicine-hypotonic citrate method outlined by

Hsu and Patton (1969), but with the following minor modifications: (1)

the bone marrow-citrate suspension was incubated for 30 minutes rather than for 5-10 minutes; (2) 0.9% citrate was used instead of 1%; (2) the filtrate was centrifuged at 1030 RPM rather than at 500 KPM. Despite warnings that wild mammals held in captivity for several months cannot be karyotyped successfully due to reduced mitotic activity (Lee 1969; 10

E. L. Roth, pers. comm.), I obtained satisfactory karyotypes from chip­ munks caged for five to twelve months.

Chromosomes were photographed with a Wild Micro-Photoautomat camera and Kodak High Contrast Copy film.

Spermatozoa

Testes were removed from freshly killed specimens and were fixed in a solution consisting of 2 parts 100% methanol, 4 parts 95% ethanol,

1 part acetone, 2 parts chloroform, and 1 part 100% propionic acid

(Forman 1968). This fixative works very well but apparently must be prepared within a few weeks before use. Tubule fragments were teased apart in lactophenol mounting medium (Linder 1929) with 0.3% aniline blue.

Spermatozoa were viewed under oil immersion at 1500x and drawn by camera lucida.

Vocalizations

Fig. 27c (p. 133) was recorded with a Uher 4000 Report-L tape re­ corder and Uher M-514 microphone. Figs. 27a and 27b were recorded with a

Sony 800B recorder, a Sony Electro-Voice 1711 microphone, and a Sony PBR-

400 parabolic reflector. Both recorders were set at 7-1/2 inches per second. The recordings used in Fig. 2 (p. 24) were provided by P. Smit, and were made at 3-3/4 inches per second on an unknown recorder. Sono­ grams were prepared with a Kay Sona-Graph 6061 B.

Statistical Analysis

Standard univariate statistics (mean, range, variance, standard deviation, standard error of the mean, and coefficient of variation) were 11 obtained by use of the SPSS Condescriptive program. I used a hand calculator to compute these statistics for some of the smaller sam­ ples. Student's t, F, and (chi-square) tests were also performed on a calculator, as were the regression analyses (Snedecor and Cochran

1971). The t' statistic (Sobal and Rohlf 1969:374) was used in place of Student's t in the case of unequal variances. Unless stated other­ wise, the .01 confidence level is regarded as significant.

Linear discriminant analyses of cranial and external measure­ ments were performed using the SPSS Discriminant program. The data were corrected for allometry (Corruccini 1972) using a program (ALOM) written by Dr. John K. Cross. CHAPTER 3

TAXONOMIC CRITERIA

If you describe things with the right tensors All law becomes the fact that they can be described with them; This is the Assumption of the description. The duality of choice becomes the singularity of existence . . .

William Empson, Doctrinal Point

An axiom of systematic biology is that any taxonomic character

varies greatly in its information content from one group of organisms

to another (Mayr 1969). Before characterizing species and subspecies

(Chapters 5 and 6), it is necessary to discuss the nature and signifi­

cance of the characters upon which certain inferences will be based.

Ossa Genitalia

Burt (1960) reviewed the early literature dealing with the mam­

malian baculum. The first comprehensive study of this character in the

Sciuridae was that of Pocock (1923), who recognized that cranial and

dental characters have limited taxonomic value in this group. Howell

(1929) scarcely mentioned the baculum in his revision of the American

chipmunks, although apparently he believed it to have some significance

at the generic and subgeneric levels (Howell 1929:27). Wade and Gilbert

(1940:52) described the bacula of several North American sciurids and

noted that "American mammalogists generally, have been slow to recognize

this structure as a valuable aid in determining group relations."

12 13

White (1953a, 1953b) established that the baculum is a reliable

taxonomic character in Eutamias, and noted that a classification of species groups based on this character differs greatly from that pro­

posed by Howell (1929) on the basis of classical criteria. Layne (1954)

described the baubella of a number of sciurids, including four chipmunk species, and stated that this character might have taxonomic value.

A number of sibling species in Eutamias are recognizable pri­ marily by the ossa genitalia. They are E_. merriami and El. obscurus

(Chapter 6); IS. cinereicollis and IS. canipes (Fleharty 1960); E^. ruf i- caudus simulans and E_. amoenus (Johnson and Ostenson 1959) ; J2. quadri- vittatus and E^. umbrinus (Long and Cronkite 1970); and 12. townsendii,

I!, ochrogenys, E. senex, and E_. siskiyou (Sutton and Nadler 1974). Ac­ tually this list is quite arbitrary, because "sibling" species are sim­ ply species that a given taxonomist perceives as similar (Steyskal 1972).

The functional significance of the baculum is unknown, but one is reminded immediately of certain invertebrate groups in which differ­ ences in genital structure serve a lock-and-key function. Mayr (1970:

64) discredited mechanical reproductive isolation as a widespread phe­ nomenon, while conceding its importance in pulmonate snails and certain

Dipteran flies. Paulson (1974) demonstrated mechanical isolation in damselflies, and there is circumstantial evidence for its occurrence in certain other insects (e.g., Callahan 1972, 1974) and even in reptiles

(Goin and Goin 1971:189).

Mechanical isolation is rarely proposed for mammals unless there are gross differences in the size of the genitalia (e.g., Flsler 1965), i i

14

Such differences may arise incidentally by pleiotropy; according to

Mayr (1970:64), the rest of the phenotype may be preserved by devel­

opmental canalization while the genitalia are accumulating these ran­

dom modifications. It is difficult to understand, however, why the

genitalia should be the only morphological structures conspicuously

immune to canalization in so many unrelated groups of animals. This

exception seems particularly unlikely in rodents, because pregnancy in

many rodent species is known to be dependent upon specific male genital

structures and/or copulatory behavior (Dewsbury 1975). Unfortunately,

virtually nothing is known of the reproductive physiology of Eutamias

(Asdell 1964).

Because a number of chipmunk species have similar bacula, it

seemed advisable to determine whether such species tend to be allopat-

ric, as would be expected if the baculum is operative in reproductive

isolation. Table 1 demonstrates that such is not the case. Approx­

imately the expected number of species pairs appears in each of the

four cells (P > .50). However, of the 11 sympatric species pairs pos­

sessing similar bacula, 10 belong to White's (1953b) Group I. Species

in this group exhibit a reduction and simplification of the baculum but

differ greatly in other characters. The baubella are more variable in

shape in this group than in White's other groups, and are absent from

occasional individuals (pers. obs.). I infer that the function of the

ossa genitalia, whatever that function may be, has been lost in the

Group I species and that the bones themselves are in the process of

being lost. 15

TABLE 1. Bacular characteristics of sympatric and allopatric Eutamias species.

A = allopatric, C = either sympatric or parapatric, S = similar, D = different; AL = alpinus, AM = amoenus, BU = bulleri, CA = canipes, CI = cinereicollis, DO dorsalis, ME = merriami, MI = minimus, OB = obscur- us, OC - ochrogenys, PL = palmeri, PN = panamintinus, QM = quadrlmacu- latus, QV = quadrivittatus, RtT = ruficaudus, SE = senex, SI =-• siskiyou, SO = sonomae, SP = speciosus, TO « townsendii, UM = umbrinus.

AL AM BU CA CI DO ME MI OB OC PL PN OM OV RU SE SI SO SP TO UM

AL X CS AD AD AD AS AS CS AD AD AD AD CD AD AD CD AD AS CD AS CD

AM X AD AD AD CS CS CS AD AD AD AD CD AD CD CD CD CS CD CS CD

BU X CD AD CD AD AD AS AP AD AD AD AD AD AD AD AD AD AD

CA X AD CD AD CD AD AD AD AD AS AS AS AD AD AD AD AD AS

CI X CD AD CD AD AD AD AD AS AS AS AD AD AD AD AD AD

DO X AS CS AD AD AD AD AD CD AD AD AD AS AD AS CD

ME X CS CD AD AD CD CD AD AD CD AT AS CD AS AD

MI X AD AD AD CD CD CD CD CD AD AS CD CS CD

OB X AD AD AD AD AD AD AD AD AD CD AD AD

OC X AD AS AD AD AD AS AD CD AS AD AD

PL X CD AD AD AD AD AD AD AD AD AS C PN y AD AD AD AS AD AD AS AD CD

OM 11 28 X AS AS CD AD AD CD AD CD S QV (9.3) (29.7) X AS AD AD AD AD AD CD

RU X AD AD AD AD AD AD

SE 42 129 X CD CD CS AD AD Q SI (40.7) (130.3) X CD AD CD AD

SO X AD AS AD

2 SP X = 0.37, P. > .50 X AD AD

TO (Expected frequencies in parentheses) X AD

UM X 16

A similar trend is apparent in many other mammals, including several sciurids. In Tamiasciurus, and in several of the Funambulini,

the ossa genitalia have been lost or reduced to irregular fragments

(Pocock 1923, Layne 1952, Moore 1959). Other examples of secondary loss are found among the insectivores, of which only the primitive ten- recs retain well-developed bacula (Hamilton 1940, Pearson 1944, Didier

1951, Eckstein and Zuckerman 1956); carnivores (Fells domesticus; Ruth

1934); and primates (Homo). Jellison (1945) and Layne (1954) similarly concluded that the ossa genitalia tend to be reduced in more special­ ized or derivative taxa.

Thus 10 of the apparent exceptions in Table 1 do not argue against the involvement of the baculum in reproductive isolation, for they involve a group of species in which this mechanism is unlikely anyway. Eutamias speciosus and JE. senex, the remaining exception, are very different in general appearance and apparently have achieved more efficient ecological segregation than is usual among chipmunks (Grin- nell and Storer 1924); ethological and ecological isolating mechanisms are likely to be operative in this instance.

Apparently all well-documented cases of natural interspecific hybridization in rodents involve genera with simple, rod-like bacula

(e.g., Peromyscus, Thomomys, and Perognathus). All the Sciuridae pos­ sessing bacula have elaborate ones, as compared with those of most other rodents, and in this family no proven interspecific hybrid has ever been reported (Gray 1972). Squirrels suspected to be hybrids on the basis of external characters have later proven to be aberrant 17

individuals of one species or another (Hansen 1956, Sheppard 1965:47;

but see Deniscrv 1961).

Mossman (1953) pointed out that the baculum and other repro­

ductive structures are not subject to environmental selection and

should therefore reflect taxonomic relationships, Atelic characters in

general are considered to have high taxonomic weight (the "Darwin Prin­

ciple"; Mayr 1969). If the baculum is involved with reproductive iso­

lation in certain genera, however, then a potential taxonomic limitation should be kept in mind (Marler 1957:35): "Signals that are in some way

involved in reproductive isolation are likely to be highly divergent

between closely allied sympatric species. They will therefore be use­ ful as characters for specific diagnosis, but of limited value at higher levels of classification."

Layne (1954) and others have belittled the female os genitale on

the grounds that it is small and difficult to prepare. These are not valid criticisms; many things are small. From a practical standpoint the baubellum is actually a more convenient character than the baculum, for the latter (in my experience) is rarely present on chipmunk study skins unless the preparator has deliberately preserved it. The baubel­ lum seems always present, unless the preparator has cut through the gen­ ital region. It is somewhat more variable in shape than the baculum and is therefore less useful at the species level, but normally the two or three chipmunk species coexisting in a given area can be identified by the baubellum as easily as by the baculum. Moreover, in many cases the baubellum unexpectedly reveals homologies and relationships not evident from the baculum. The reason is unclear. Perhaps because the

female os genitale is incompletely developed, it reveals ontogenetic

stages which may, in some instances, reflect phylogeny. Whatever the

reason, the evidence follows.

Jellison (1945) suggested that the baculum of placental mammals

may be derived from the paired epipubic bones found in living marsupials

and in fossils of mammal-like reptiles. During the embryological devel­

opment of the dog and fox, the baculum is formed by the fusion of paired

elements. In the primitive insectivore family Tenrecidae, and in Aplo-

dontia, generally considered to be the most primitive living rodent, the

baculum is bifurcated throughout life (Didier 1951, Burt 1960). The

baubellum of Aplodontia, which apparently is homologous to the proximal

portion of the baculum (Scheffer 1942), is even more strongly bifurcated.

Because the squirrels are the next most primitive rodents, and

because the chipmunks are (among?) the most primitive squirrels (see

Chapter 4), it seems reasonable that the ancestral chipmunks may have

had partially divided bacula. While this condition is not very apparent

in most of the living chipmunks, those species with the largest bacula

have more or less of a notch in the base, and a faint groove often con­

tinues along the shaft from this notch (Figs. 15, p. 93; 23, p. 121; 28,

p. 135). The baubella of such species are very clearly divided at the

base (Figs. 15, 23; 29, p. 136). Even within certain species, those

populations with longer bacula tend to have double-based baubella

(Chapter 5), while those with shorter bacula have single-based baubella

or, occasionally, none at all. Thus the apparent evolutionary trend 19

toward reduction and simplification of the os genitale is accompanied by

fusion; and the latter is more clearly observed in the female.

The bacula of the Sciurini and Citellus characteristically have

a bony process or spur on the ventral surface of the tip (Burt 1960).

This spur is absent from the bacula of most chipmunks, but it is present

on the baubella of most species and individuals (Figs. 15, 23, 29; 7, p.

55; 11, p. 72; 16, p. 94). The spur is often absent, however, in those

taxa with reduced ossa genitalia (Fig. 7, and pers. obs.).

In summary, while the ossa genitalia of both sexes are of great value in sciurid taxonomy, the baculum appears to provide more infor­ mation at the species level and the baubellum at higher taxonomic levels.

Karyology

Prior to my study virtually all cytological studies of chipmunks were performed by C. F. Nadler and associates (Nadler and Block 1962;

Nadler 1964; Sutton and Nadler 1969; Nadler, Hoffmann, and Lay 1969).

Nakamura (1953) had previously karyotyped Eutamias sibiricus and had established the diploid number as 38. Thompson (1971) karyotyped two

Nearctic species and verified Nadler's results. Callahan (1975, 1977) and Callahan and Davis (1977) were the first to karyotype IS. bulleri and several other Mexican taxa (Chapters 5 and 6).

Nadler has described four chipmunk karyotypes: one for the east­ ern chipmunk, Tamias striatus, one for Eutamias sibiricus, and two, desig­ nated as A and B, for the western chipmunks (Eutamias, subgenus Neotamias).

In all species examined, 2n = 38 and the sex chromosomes are of the 20

conventional X-Y type. On the basis of gross chromosomal morphology,

these four karyotypes appear quite similar (Nadler et al. 1969).

Neotamias-A can (on paper) be converted either to Neotamias-B or to the

Tamias striatus karyotype by a single pericentric inversion. Neotamias-A

can similarly be converted to the _E. sibiricus karyotype by one or two

pericentric inversions plus a translocation onto the Y chromosome (a

possibility denied by Nadler, despite precedents; Ohno 1969).

Nadler, Hoffmann, and Hight (1975) reported that Giemsa banding

confirmed the similarity of Neotamias-A and -B and supported the hypoth­

esis of a single inversion. However, banding also revealed a lack of

homology between several chromosome pairs of Tamias striatus and the

corresponding pairs of Neotamias. This work illustrates the fallacies

that may result from conventional chromosomal analysis; the eastern and western chipmunks are clearly more divergent than conventional methods had indicated. Unfortunately, Asiatic specimens were not available for

G-banding, but the gross differences between the chromosomes of IS. sibiricus and those of Neotamias are considerable,

Although chromosomal data support the recognition of three chip­ munk subgenera or genera (Chapter 4), they reveal little or nothing about the direction of evolution in this group. Nor can the subgenus Neotamias be divided into two meaningful species groups solely on the basis of karyology, for at least two species—E_. obscurus and E. -minimus—exhibit karyotype A in one geographic area and karyotype B in another (Callahan

1977, Sutton and Nadler 1969). The J3. quadrivittatus superspecies, as 21

defined in Chapter 6, also includes both karyotypes (Sutton and Nadler

1969).

Karyotype A is known only from the Rocky Mountains (E. minimus)

and geologically associated ranges of the Southwest, including the

Sierra Madre and the Peninsular Ranges; minimus populations possessing

A have apparently leaked over to the Great Lakes region as well. B, on

the other hand, is the only karyotype found west of the Rockies. This

pattern suggests that the inversion may have some ecological signifi­

cance. The areas in question differ, for example, in the seasonal dis­

tribution of rainfall. Neither convergence nor ecotypic variation in

chromosomal morphology is unprecedented in rodents (e.g., Rerry and

Baker 1971; Patton 1970). The ancestral chipmunk species may have

passed through a stage of chromosomal polymorphism which later "col­

lapsed" into monomorphism in local populations (White 1969).

Vocalizations

Miller (1944) was among the first authors to categorize chipmunk

vocalizations and to attempt to interpret their significance. He stated rather categorically that these calls must function in species recog­

nition. Brand (1970), however, found that the courtship vocalization

(the chatter, which Miller did not describe) does not differ even among

sympatric species. The other vocalizations he described, other than the self-explanatory female growl, were apparently unrelated to reproductive behavior. Moreover, interspecific aggression does not usually involve vocalizations (see Chapter 7). 22

Morton (1975) demonstrated that bird species occupying habitats with similar acoustic properties tend to produce similar sounds. Mam­

malian vocalizations may be influenced by similar factors (D. Hobbs,

unpubl.), but no general pattern has been established. Brand (1970)

reported that Eutamias merriami and _E. sonomae, which occupy equivalent

habitat on opposite sides of San Francisco Bay (Hooper 1944), have

quite different calls; while Dunford and Davis (1975), on the other hand, found no differences between the vocalizations of montane and desert populations of E^. dorsalis.

If chipmunk vocalizations are indeed unrelated to reproductive isolation, and uninfluenced by ecological factors, then they have con­ spicuous taxonomic advantages which may be outweighed only partially by their unknown heritability. I will deal with each of these points separately.

Reproductive Isolation

Estrous female _E. sibiricus are said to produce characteristic sounds unlike those of males or anestrous females. Unfortunately the literature on this subject is somewhat confused. Ognev (1966) reported that hunters in the Upper Ob forest attract the male burunduk by imi­ tating the estrous female's call, using "a whistle made of a cartridge."

The sound was described as "tyurlyu-tyurlyu." Actually any odd whistling sound tends to attract chipmunks, and I am suspicious of this story.

Smit (1976), however, states that the Zwitschern (= "twitter", which he considers homologous to the chip of the Nearctic species) is 23

given by the inactive estrous female sibiricus and also by highly active

individuals of either sex. Herr Smit has provided a recording of this

call, given by a caged female "when she wanted a male" (sic). Sadding-

ton (1966) similarly reported that the onset of estrus in this species

coincided with the initiation of calling to a male in a separate cage.

A sonogram of Smit's Zwitschern recording appears in Fig. 2a.

Note that the chevron is followed by either one or two distinct pulses;

there are two in the first recording shown in Fig. 2a, but they are par­

tially obscured by background noise. These calls were given at a rate

of approximately 20 per minute.

The chlp/Zwitschern is primarily an alarm call, and its rele­ vance to courtship is obscure. However, Dunford (1970) noted- that

Tamias striatus has an "unspecific" communication system in which the

same vocalizations used as alarm calls are also agonistic signals.

Dunford (1972) further reported that the chip-trill (normally an alarm

call) of a male T^. striatus apparently attracted an estrous female.

Alarm calls are not known to be involved with the reproductive behavior of western chipmunks, but the following observations of caged specimens may be relevant. In January 1974 I introduced a male IS. dor- salis sonoriensis into a cage containing a female _E. obscurus meridi- onalis (as a prelude to planned hybridization experiments which, however, have not yet been carried out). The only sound this male had produced during two months in captivity, or during a week of field observation prior to collection, was the chip. Seconds after it landed in the new cage, it approached the female in a hesitant manner, giving 24

PIN* BROOK. M.J.

I T \ ft

J (ti II

JiUW?"Jb ^lihSbrr.. t 'Am TYWt »/«B tONAQRAM• KAY CLICTRIC CO. PINK SHOOK. N. J.

itwl&Ui

Fig. 2. Sonograms of Eutamias sibiricus vocalizations. a, Zwitschera or chips; composite of three recordings, b, Fauch- laute, continuous series. 25 a series of low hiccup-like notes resembling the chuck (also an alarm call; see Chapter 6). It stopped vocalizing after 30 seconds or so and attempted to copulate with the female, who evinced no hostility. This activity was observed daily for the next two weeks, although no further vocalizations were heard. Dobroruka (1972) stated that the courting male E. sibiricus gives a "baby call" (not described) which inhibits the female's aggression.

Behavior under laboratory conditions is always difficult to interpret. However, Brand (1970) found that sympatric Eutamias species respond to one another's alarm chip and chuck. Therefore even if these calls are involved with reproductive behavior, it is unlikely that they could function as isolating mechanisms, unless species are identified by the temporal patterning of calls (Chapter 6; Brand 1970:120).

The Effect of Environment

There are four major varieties of the chip in Eutamias. These are the simple chip, which produces a chevron-shaped sonogram; the E. sonomae chip, with a V-shaped sonogram (Brand 1970); the chip with ter­ minal pulse, which I will call the chipm (this includes at least some of the Zwitschern calls, as in Fig. 2a); and the chip-quaver of E. bulleri

(Chapter 6). The chipm is of particular taxonomic interest, because it occurs in several apparently unrelated species.

Brand (1970) found that about half the chip calls given by 15. panamintinus included the pulse. No other species included in his study produced this sound. Dunford and Davis (1975) reported a similar call for 15. dorsalis. Both panamintinus and dorsalis inhabit semiarid, rocky

areas.

IS. palmeri, a Great Basin endemic like 15. panamintinus, also

gives the chipm about as often as the simple chip (pers. obs.). Unlike

either panamintinus or dorsalis, however, palmeri is found only at

high elevations and is not closely restricted to rocks, although it

often inhabits rocky areas and may nest in crevices (Burt 1934:408;

Deacon, Bradley and Larsen 1964). E. umbrinus, a close relative of E.

palmeri, is reported not to give the chipm (Brand 1970).

One individual 12. obscurus, an estrous female, was heard to give

the chipm (Chapter 6). This species is a rock-dweller but not a resi­ dent of the Great Basin, and it normally gives the simple chip.

One female 15. bulleri produced chipm-like calls (Chapter 6), but only after having been caged for some months adjacent to an JE. dorsalis

(which, however, was not heard to chipm in captivity, so learning can probably be ruled out here). 15. bulleri is both a rock-dweller and a relative of 15. obscurus.

Finally there is J5. sibiricus (Fig. 2a), which belongs to a separate subgenus, does not live among rocks (Ognev 1966, Snigirevskaya

1962, Stilmark 1963), and certainly does not occur in the Great Basin.

Note that the chipm ends more abruptly than does the simple chip.

The pulse acts, so to speak, as an exclamation point, giving the syllable an incisive quality. Theoretically the chipm should be the easier call to locate by binaural time-comparisons (Marler 1955). It may therefore be an improvement on the simple chip, but only if one of the following I 27

is true (see also Barash 1975): Cl) location by other chipmunks raises

the caller's fitness sufficiently to outweigh the disadvantages of

possible location by predators; or (2) the structure of the habitat is

such that the caller can escape easily if detected.

The first condition applies to species in which an individual in

breeding condition solicits vocally. It may also apply to sympatric

species—such as IS. palmeri and JE. panamintinus—that can benefit from

common alarm calls (see Moynihan 1968, Cody 1969), assuming that one of

the species already has the chipm. The second condition applies partic­

ularly to species occupying rock cliffs. These explanations appear to

cover all bases.

While the chipm may be adaptive, it may also be interpreted as a

purely atelic character; its acoustic properties have not been tested

experimentally, and in any case the selection differential is probably

slight. A third possibility is that all Eutamias species can produce

the chipm, given adequate stimulus. All three alternatives are simplified

by the assumption that the chipm is an ancestral rather than a derived

character.

Brand (1970:118) suggested that the simple chip is ancestral,

probably because only one species included in his study gave the chipm.

An ancestral character is typically scattered among distantly related

taxa (Mayr 1969), and most of the six species now known to produce the

chipm—panamintinus, dorsalis, palmeri, obscufus C?), bulleri (?), and

sibiricus—are not closely related, or at least not more so than any

random sample of the world's chipmunks. Even if common environmental 28

factors are involved, parallel selection is more likely than convergence,

for the latter would not be expected to produce five virtually identical

sounds. Ease of location (or whatever) could be achieved by any of a

number of different modifications of the simple chip. Also, certain

other sciurids have an alarm note resembling the chipm. My field notes

describe one call of Sciurus griseus as "SQUEE(unk) SQUEE(unk) SQUEE(unk)11

etc., and one call of Citellus beecheyi as "CHIZZ(um)!" etc. The corre­

sponding transliterations of the Eutamias chipm and chip would be

"WHISS(unk)!" and "WHISK!" respectively.

The taxonomic use of chipmunk vocalizations is complicated by

an apparently high degree of individual, seasonal,, and/or geographic

variation. Dunford and Davis (1975) reported (and I concurred) that

12. dorsalis in the Santa Catalina Mountains does not give the trill

(as defined by Brand 1970). However, of approximately 30 dorsalis live-

trapped at Rose Canyon and Molino Canyon during April 1976 (for use in a

different study), three gave short but distinct trills as I approached

their traps. One female continued to trill for at least five minutes

while I carried the trap. These were the same populations studied by

Dunford; I even used the same traps. Nor am I confusing the trill with

the chipper, a different call (Brand 1970). My only explanation is that

the population density was extremely high in 1976, and it is possible

that the animals were unusually stressed as a result. -E. merriami some­ times gives the trill during agonistic encounters CChapter 6). Also, a caged E. bulleri was observed to prolong the dorsalis-like chipm into a trill when greatly alarmed (Chapter 6). 29

Brand (1970) reported that E^. minimus scrutator and 12. amoenus in California did not give the trill, but I found that scrutator in western Nevada gave this call frequently, and Broadbooks (1958) clearly described a call corresponding to the trill in his account of IS. amoenus in eastern Washington.

Finally, E. A. Larson writes (pers. comm.) that a caged 10-year- old E_. dorsalis from the White Mountains of Arizona produces a whistle

"when taken unawares by surprise" (sic). Neither Dunford and Davis

(1975) nor I have ever heard dorsalis make this sound. Brand (1970) described it for J3. speciosus, E_. amoenus, and 12. alpinus.

In conclusion, it appears that all Eutamias species may poten­ tially be able to produce all or most of the calls given by the genus as a whole. Matocha (1975) found that Citellus vocalizations are genet­ ically controlled but also modified by learning; it would be interesting to determine the relative roles of these factors in the vocal behavior of Eutamias.

Other Characters

Spermatozoa

Taxonomists have described the spermatozoa of a number of rodent taxa (Friend 1936, Hirth 1960, Genoways 1973). The results have proven uniformly interesting. The unusual spermatozoa of Ochrotomys nuttalli, for example, in conjunction with other characters, supports its generic separation from Peromyscus (Hirth 1960). Genoways (1973) found three 30 general types of sperm in Liomys, corresponding to the three species groups indicated by other characters.

One problem with this character—and this was not noted by any of the authors cited above—is that the shape of the acrosome changes, at least in some species, as the sperm matures during its passage through the epididymis (Fawcett and Hollenberg 1963). Pfeiffer (1956) reported that the mature sperm of Aplodontia rufa bears a large galea capitis, somewhat resembling a parachute. Without this structure the sperm presents an entirely different appearance, and the epididymis contains a mixture of the two types. Also, the immature sperm of all mammals retains a cytoplasmic bead or droplet in the neck region (Hadek 1969,

Zamboni 1971); many of the "species characteristics" described and illus­ trated by Hirth (1960) clearly refer to immature vs. mature sperm.

Fig. 3 shows the spermatozoa of four of the five Eutamias species included in my study. The first four drawings (E. merriami, 12. obscurus, and two subspecies of dorsalis) are alike. I was unable to make a strictly comparable drawing for 12. bulleri, because all available sperm were immature (Chapter 6), and the large cytoplasmic bead pre­ vented the head from laying flat on the slide. However, the edgewise and three-quarter views which were obtained indicate that the basic structure is like that of the other three species. The one distinctive feature in bulleri is the cone-shaped galea capitis present on many of the sperm.

This seems to be a flexible structure, unlike the rigid hook-like ap­ pendage seen on the acrosome of many rodents. It was not present on any of the (mature) sperm taken from the other three species. 31

Fig. 3. Spermatozoa of four Eutamias species.

All l400x; a-d are mature sperm, e-i immature sperm, a, _E. dorsalis dorsalis (field no. 124). b, _E. d. sonoriensis (USNM 398643). c, 12. merrlami merriami (field no. 214). d, _E. obscurus davisi (field no. 213). The remaining drawings are of 12. bulleri: e, field no. 217, 3/4 view, without galea capitis, f, field no. 216, 3/4 view, with galea capitis, g, field no. 217, side view, h, field no. 217; note position of cytoplasmic bead. 1. field no. 217, side view, without galea capitis; note position and size of cytoplasmic bead. 32

I was unable to determine from the literature whether or not it is possible for such a large structure to be present on the immature sperm and subsequently lost. In the hope of clarifying this problem I examined the spermatozoa of another sciurid, Citellus variegatus (Fig.

4). All the structural types shown were obtained from the same frag­ ment of epididymis. Although the galea capitis is remarkably similar to that of Aplodontia, in which Pfeiffer (1956) implied that it repre­ sents the final stage of maturation, it was never present on a Citellus sperm that had resorbed its cytoplasmic droplet. Furthermore, Pfeiffer' own photomicrograph clearly shows a galea capitis in the process of becoming detached from a mature sperm, a stage not represented in my material. An adjacent immature sperm in his photo still bears the galea capitis.

I conclude that in Aplodontia, Eutamias, and at least this one species of Citellus, the following sequence of stages occurs during the passage of the spermatozoan through the epididymis. (1) A large cyto­ plasmic bead is present, as in other mammals. (2) The galea capitis is acquired (how?). (3) The bead gradually migrates along the neckpiece distal to the head, as in other mammals, and is resorbed (see Figs. 3e-i

4). (4) When the droplet is very small, or completely resorbed, the galea capitis becomes detached and is lost. An electron microscopic study of this process should yield interesting results.

This example clearly illustrates the importance of obtaining mature sperm for taxonomic comparisons. It also suggests that the matu- rational stages themselves may provide critical information. Although 33

a

Fig. 4. Spermatozoa of Citellus variegatus.

All drawings 1500x. Specimen, uncatalogued road kill; from Mt. Lemmon, Pima Co., Arizona, a, side view, without galea capitis, b, 3/4 view, with galea capitis, c, full view, and d, side view, without galea capitis or cytoplasmic bead. I

j

34

the mature sperm of Citellus variegatus and Eutamlas are quite similar,

except in size, the (transitory) galea capitis of C_. variegatus resem­

bles that of Aplodontia rather than that of Eutamias. These facts

cannot be evaluated until more species have been studied, but they are

interesting in view of the great antiquity and uncertain taxonomic

position of Aplodontia.

If the four Eutamias species included here are typical, then

spermatozoan morphology in this genus apparently has little taxonomic

value at the species level.

Sexual Dimorphism

Secondary sex characters in Eutamias have received little atten­

tion. Most taxonomists have discounted this source of intraspecific

variation, apparently because of the inconvenience of comparing the

sexes separately (Howell 1929, Johnson 1943, Lidicker 1960). Fleharty

(1960) stated that E. canipes Sacramento ens is is not sexually dimorphic,

but I examined all his specimens (and a number of others; Appendix A)

and found a considerable degree of dimorphism (Appendix B). Genoways and

Jones (1973) examined 20 13. bulleri from Jalisco and stated that the

species is not dimorphic; however, I found that only five of those 20 are

adults and that only eight, including four subadults, include skins and

have external measurements recorded. The species is dimorphic (App. B).

Sexual dimorphism may be inconvenient for the working taxonomist,

but it is also a population characteristic of great potential signifi­

cance. At least three patterns of dimorphism occur in Eutamias. In

E. obscurus, E_. sibiricus, E_. ruficaudus, E_. minimus, and certain 35

subspecies of 15. canipes, females are significantly larger than males

(Appendix B; Chapter 6; Ognev 1966; Beg 1969). This appears to be the

typical and perhaps the ancestral pattern. E_. dorsalis and IS. merriami,

however, are significantly dimorphic for only one or two cranial char­

acters (Chapters 5 and 6; Appendix B). These two species are usually

considered to be closely related (Howell 1929); also, each is rather

specialized ecologically, a fact suggesting that subniches may not be

available for the sexes (Rand 1952; Selander 1966, 1969; Smouse 1971).

E_. bulleri exhibits a third pattern of dimorphism: males have

narrower (but not shorter) skulls, smaller bodies, and much longer

tails than do females. This is precisely the same complex of characters

found in the (nondlmorphic) desert subspecies of JE. obscurus and _E. dor­

salis as compared with their montane counterparts (Chapters 5 and 6).

Circumstantial evidence therefore suggests that male _E. bulleri have

a greater problem with heat than do females, perhaps due to differences

in foraging behavior or in temporal or seasonal activity patterns. In

certain other Eutamias species the sexes are known to use patchy habi­

tats differently (Meredith 1972) or to be active in different seasons

(Chapter 6; Dunford 1974).

Some cases of sexual dimorphism in mammals may be neutral by­

products of hormonal action or of allometric growth (Rensch 1950,

Glucksmann 1974) and may therefore have little evolutionary signifi­

cance. J5. bulleri would be an ideal species with which to test this hypothesis, because its pattern of dimorphism lends itself to ecological interpretation. Regardless of the significance of dimorphism, however, it exists and cannot be neglected in taxonomic work. The pattern of dimorphism is also a taxonomic character in itself; for example, the chief difference between E_. canipes sacramentoensis and JE. c_. canipes is that the former is strongly dimorphic while the latter is not. Males of the two subspecies appear to be nearly identical (Appendix B).

Cranial Characters

The skulls of most Eutamias species differ quantitatively, but a multivariate approach is necessary because of extensive overlap in any single character. Qualitative cranial differences are few, at least in the species I have studied. Hall and Kelson (1959:310) stated that the incisive foramina of 12. dorsalis diverge posteriorly, unlike those of certain other species; however, the foramina are parallel in most E_. d. dorsalis and 15. jd. sonoriensis I have examined. The same authors used incisor recurvature as a diagnostic character in Eutamias, but this is highly variable in some species (Chapter 6). The best skull character in general is the relative flatness of the braincase.

Davis and Schwab (1964) found that cranial depth (CD; Chapter 2) is the best single skull character by which E_. d_. dorsalis and E_« obscurus

(then IJ. merriami obscurus) can be separated. They also found that this character was not sexually dimorphic, even in the highly dimorphic ob­ scurus , and was therefore convenient for taxonomic comparisons. CD is not dimorphic in any of the five species I have studied either, and its coefficient of variation is consistently low (see Appendix B). It is the best cranial character for separating a number of species and sub­ species, as discussed in Chapter 6. 37

Bryant (1945) noted that the cranium was flattened dorsoventrally

in Miocene sciurids and that there has been a trend toward convexity,

particularly in the tree and flying squirrels. It is difficult to test

a relationship between cranial convexity and arboreal habits in chip­

munks, because of inadequate and/or conflicting information regarding

the habits of most species. All chipmunks apparently climb trees at

times, and the proportion of time spent in trees varies seasonally with

the location of food (Beg 1969). A better criterion of "arboreality"

would be the use of trees for refuge. 15. umbrinus, E. cinereicolUs,

J5. speciosus, and 15. ruficaudus are reported to escape regularly by

climbing trees (Brown 1971, Bailey 1931, Grinnell and Storer 1924, Orr

1943), and 35. merriami, if approached while calling from a tree, will

usually stay there (pers. obs.). Sheppard (cited by Miller 1967) found

that 15. amoenus frequently took refuge in trees, while 15. minimus did so

less frequently; Orr (1943), however, found E^. amoenus to be a strictly

terrestrial species. E^. obs cur us, E_. bulleri, E. alpinus, 15. sense,

15. quadrimaculatus, 15. panamintinus, and E^. dorsalis are species that

apparently do not remain or take refuge in trees if approached (pers.

obs.; Grinnell and Storer 1924; Johnson, Bryant and Miller 1948; Brown

1971). In the "arboreal" group, all but £. merriami (the least arboreal,

as defined here) have markedly convex skulls. The skull of 15. minimus

is less convex than that of the more (?) arboreal sibling specie^E. amoenus. In the "terrestrial" group, excluding the problematical^amoenus, all but jE. bulleri have markedly flat skulls. Both the exceptions, merriami and bulleri, have skulls of intermediate convexity. Clearly there Is a relationship here between form and habit, although its

functional significance is not apparent.

Hyoid Bones

White (1953a) compared the hyoid of Tamias striatus with that

of Eutamias, represented by _E. minimus, and found that the two genera

differ in that the hypohval and ceratohyal become fused in adult

Eutamias. His illustrations appear quite dissimilar because of the

great difference in overall size between T_. striatus and 15. minimus;

in the larger species of Eutamias, however, including the five I have

studied, the hyoid is about the same size as in striatus. In all

other respects the structure is essentially as in E. minimus, so no

illustration is provided here. The size of the hyoid presumably is in

proportion to that of the jaw, with which its movements are coordinated

(Crompton and Cook 1975).

A series of hyoid bones from IS. merriami and 15. obscurus reveals a geographic trend of unknown significance. The hypohyal of 15. m. price!

is wide and thin, while that of E. m. merriami from a locality some 250 miles to the southeast is narrower and elliptical in cross-section.

Another 150 miles to the ESE, the hypohyal is still narrower and thicker, with a cross-section approximating a fat ellipse or football; this is in the region of sympatry with _E. obscurus, which has the same hyoid struc­ ture. Finally, at the southern limit of jE. obscurus—another 500 miles to the south—the hypohyal is nearly cylindrical.

Such a trend might be related to food habits or to vocal behavior, as in certain other mammals (Sprague 1941), but I am more inclined in this instance to attribute the trend to a parallel geographic trend in cranial depth and in skull size generally (Chapter 6). Any change in the proportions of the cranium might well be accompanied by allometric changes in the articulation of the lower jaw and its associated struc­ tures. At the species level, however, the hyoid appears to be of little taxonomic value in Eutamias. CHAPTER 4

CHIPMUNKS AS SQUIRRELS

A good name is rather to be chosen than great riches.

Proverbs, XXII, 1

Status of Tamias

Before 1897 all North American and Asian chipmunks belonged to the genus Tamias. Two subgenera were recognized: Tamias, which in­ cluded the eastern North American chipmunk T?. striatus, and Eutamias, which included the remainder of the genus.

Merriam (1897) recommended that Eutamias be given full generic rank, for he believed that Tamias striatus was derived from the ground squirrel subgenus Ictidomys and that Eutamias was derived from Ammo- spermophilus. He offered no evidence in support of this belief.

Howell (1929) accepted the two genera but recognized that

Eutamias sibiricus, the Asian species, is quite different from any of the North American forms. He divided the genus Eutamias accordingly into two subgenera: Eutamias, including _E. sibiricus, and Neotamias, including the remainder of the genus.

Ellerman (1940) believed that the differences between Tamias and

Eutamias were not of generic significance, and Bryant (1945) agreed.

White (1953a) favored Merriam's classification, but Nadler and associates

40 41 are currently attempting to revive that of Ellerman. Jones, Carter and

Genoways (1975) retain the generic name Eutamias.

One of the principal differences between Tamias and Eutamias is the absence of P3 in the former. Jones (1960), however, noted that

this vestigial tooth is sometimes absent in _E. sibiricus. At least 1% of all the North American Eutamias I examined for the present study lacked P3; unfortunately I did not record its presence or absence in every specimen, but it was absent, e.g., in two of 16 E. m. merriami from the San Jacinto Mountains, and in two of 23 E_. canipes solivagus from Coahuila. Interestingly, both the P3-less merriami were collected at the same locality (Alvin Meadow, 5000') during the same week.

Sciurotamias (a large Palearctic chipmunk; see next section) similarly includes two subgenera, one of which has lost P3 (Moore 1959).

Howell (1938) found that P3 was often absent in the Nearctic red squir­ rel, Tamiasciurus. The same tooth has been lost independently in the

Malayan genus Ratufa; in the African tribe Protoxerini; in the subgenera

Leptosciurus and Mesosciurus of the Neotropical tree squirrel genera

Microsciurus and Syntheosciurus respectively; and in the Bornean tree squirrel Reithrosciurus (Moore 1959). It would appear that the absence of P3 in sciurids has little taxonomic significance, and certainly none above the subgeneric level.

A second difference between Tamias and Eutamias is in the pelage coloration: the inner pair of light stripes is relatively much wider in the former (White 1953a). However, Ellerman (1940) observed correctly that this difference is trivial compared with color variation in other sciurid genera. 42

White (1953a) wrote that the baculum of 13. sibirlcus bears a

microscopic dorsal keel and therefore resembles that of the subgenus

Neotamias rather than that of Tamias striatus. I have been unable to

confirm the presence of a keel in 15. sibiricus. Also, there is a great

deal of variation in bacular structure among species within Neotamias.

The baculum of E. siskiyou, for example (Sutton and Nadler 1974), resem­

bles those of other Neotamias even less than the latter resemble Tamias

striatus or 15. sibiricus. The baubella of the three subgenera—Tamias,

Eutamias, and Neotamias—are basically similar, except for the presence

of a keel in Neotamias (Figs. 5; 7, p. 55; 11, p. 72; 15, p. 93).

White (1953a) also considered the malleus, the hyoid, several

details of the skull and teeth, the shape of the pinna, and the relative

length of the tail.

He stated that the malleus of Neotamias is similar to that of

Eutamias and different from that of Tamias, but his drawings do not

clearly support this statement. The angle formed by the lamina and man­

ubrium in Eutamias appears intermediate between the angles of Tamias and

Neotamias, although it is described as identical with the latter. In

Tamias the head of the malleus is somewhat more elongated than in other chipmunks; on the other hand, the juncture between the neck and manubrium in Tamias seems to resemble that of Eutamias and to differ from that of Neotamias.

As previously noted (Chapters 2, 3), certain elements of the hyoid become fused in adult Neotamias but not in adult Tamias. White

(1953a) stated that the fusion occurs also in the subgenus Eutamias. 43

-^7 <=^yb

Fig. 5. Baubella of Tamias striatus and Eutamias sibiricus.

All 12:;, right lateral (top) and dorsal views, a, striatus lysteri (after Layne 19S4). b, _E. sibiricus barberi (MVZ 116953). c, E_. _s. lineatus (MVZ 126863). 44

This difference supports his classification, assuming that he examined adequate series to be certain that the difference is consistent. In the course of my study I found an adult Eutamias (Neotamias) merriami (UA

23271) in which the hypohyal and ceratohyal remained separate; consider­ ing that I examined fewer than 20 hyoids altogether, some variability would appear to be indicated.

Tamias and Eutamias have in common a rounded pinna and certain cranial and dental characters not typical of Neotamias. However, White

(1953a) found that most of these cranial characters were either attrib­ utable to heterogonic growth or were shared by 12. (Neotamias) townsendii.

Also, at least two Neotamias species (E. townsendii and E;. bulleri) have rounded pinnae.

Finally, Tamias is said to have a relatively shorter tail than do other chipmunks (White 1953a). This is generally true, but there is some overlap: in E. (Neotamias) canipes durangae, for example, individ­ uals with (undamaged) tails less than 38% of total length are common.

Most conventional keys (e. g., Hall and Kelson 1959:293), following

White, state that the tail of Eutamias exceeds 40% of total length while that of Tamias is less than 38%. Even if this difference were clearcut, it is hardly spectacular compared with the variation in relative tail length observed within other sciurid genera. In Citellus, for example, tail length ranges from 20% to 50% of total length (Howell 1938).

Immunological, electrophoretic, and cytological data not avail­ able to White also support the recognition of a single chipmunk genus with three subgenera. The immunological distance between E. sibiricus 45 and Neotamias is greater than that between Neotamias and Tamias striatus

(Hight, Nadler and Hoffmann 1975). Nadler, Hoffmann and Hight (1975) similarly found that the proportion of alleles shared by Tamias striatus and 12. sibiricus is greater than the proportion shared by the latter and any Neotamias species; Neotamias is about equidistant from T_. striatus and from j5. sibiricus. The cytological evidence has been discussed

(Chapter 3).

In conclusion, it seems necessary either to recognize a single chipmunk genus Tamias, with subgenera Tamias, Eutamias, and Neotamias, or else to recognize three full genera. The latter alternative does not seem justified; both alternatives require the removal of the western chipmunks from the genus Eutamias, for its type species is IS. sibiricus

(Trouessart 1880). I have nevertheless retained the generic name Eu­ tamias in the systematic accounts that follow (Chapters 5 and 6). It would be confusing to do otherwise, because the name Eutamias is cur­ rently in general use and has of necessity been used in all my publica­ tions Based on this study.

Status of Sciurotamias

Long and Captain (1974) cited Black (1963) as having considered

Tamias to be the oldest sciurid genus surviving today. Actually Black wrote nothing of the kind; he did state that the ancestral sciurids were probably chipmunk-like, i.e., semiarboreal and relatively un- specialized. He also noted that Miocene chipmunk fossils are too in­ complete to be placed with certainty in a modern genus, and that their assignment to Tamias was largely a matter of convenience. Similarly, 46

the earliest (Miocene) tree squirrel fossils have been assigned more or

less arbitrarily to Sciurus, for the characters separating this genus

from Tamiasciurus and Callosciurus are rarely preserved in fossil

material.

The earliest known sciurid is Protosciurus, an extinct genus

which occurred over the western half of North America from the early

or middle Oligocene to the early Miocene (Black 1963). The earliest

known species, mengi, is also the smallest, and Black believed that

this lineage may have given rise to the chipmunks as well as to the

larger tree squirrels and (later) the ground squirrels. An exceptionally

well-preserved skull of j?. condoni (Black 1963, Plate 3), however,

resembles the modern Chinese rock squirrel Sciurotamias davidianus more

than any other living sciurid of which I am aware. Each has three

transbullar septa, a very flat braincase, a high squamosal, a relatively

large, broad-based postorbital process, and a large supraorbital notch

of similar shape. (Black gives Protosciurus two and one-half septa and

no supraorbital notch; however, the discrepancy in the first character

is explained by Moore and Tate (1965:27), and the notch is apparent in

Black's photograph.)

Sciurotamias is smaller than P_. condoni but nearly as large as

P^. mengi. Moreover, Black (1963:232-4) points out that an ancestral sciurid with semiarboreal habits "would be well suited to make the shift

into an open grassland habitat as well as being adapted for an arboreal habit," and Sciurotamias meets these requirements even better than do

the chipmunks or tree squirrels. All three are semiarboreal, but

Sciurotamias is also able to live like a ground squirrel in open !i | :

47

grassland (Allen 1940, Moore and Tate 1965:306), something no chipmunk

or tree squirrel can do. The appearance of Sciurotamias in the fossil

record is at least contemporaneous with that of modern chipmunks; two

fossil species are known from the Miocene of eastern Europe (Topachevsky

1971).

While I do not suggest that the ancestral sciurids were con­

generic with Sciurotamias or with any modern form, it is apparent that

they resembled Sciurotamias both morphologically and ecologically. The

taxonomic position of this genus among the living Sciuridae is contro­

versial. Ellerman (1940) believed that it is closely related to the

chipmunks, but Simpson (1945) placed it with the Callosciurini. Moore

(1959, 1961) recognized that its skull is very chipmunk-like, but he

attributed the resemblance to convergent evolution. He placed

Sciurotamias with Tamiasciurus in the tribe Tamiasciurini (primarily

because both genera possess three transbullar septa), while lamenting

the fact that the ossa genitalia and reproductive tract of Sciurotamias

had not been described; these are the characters by which Tamiasciurus

was originally separated from Sciurus (Pocock 1923; Mossman, Lawlah and

Bradley 1932; Layne 1952). Moore (1959:195) also suggested a possible

relationship between Sciurotamias and the Xerini. Black (1963), being

a paleontologist and therefore unconcerned with reproductive anatomy,

rejected the tribe Tamiasciurini. He placed Tamiasciurus in the Sciurini

on the grounds that transbullar septum counts are somewhat variable, and

he put Sciurotamias back in the Callosciurini, without even offering a

reason (except that he "felt" it belonged there). 1I I : i;

48

Thus Sciurotamias has been included, at one time or another,

with almost every existing group of squirrels. The bone of contention

is the baculum, which has never been described. Although I have been

unable thus far to locate any Sciurotamias specimens with bacula, the

American Museum of Natural History did allow me to remove the baubella

from six female skins, and in my judgment these have settled the issue.

Three subspecies of S_. davidianus are represented in Fig. 6.

The first, _S. d^. davidianus, is from Chihli (Hopei?) Province at the

northeastern limit of the species' range (Moore and Tate 1965:305).

The bone is strongly trowel-shaped; it is similar to that of Tamlas

striatus (Fig. 5a), except that the basal portion is reduced. Of all

the sciurids, only the chipmunks—or, more broadly, the tribe Marmotini

—have trowel-shaped ossa genitalia.

The next two drawings represent j[. cL owstoni from Shensi Prov­

ince, about 500-600 miles southwest of the first locality. One of

these baubella is strongly trowel-shaped like that of S_. _d. davidianus,

while the other, although retaining the same general shape, is reduced

and simplified.

Finally, three baubella of S_. cL consobrinus from Szechwan Prov­

ince are quite similar to one another but are greatly reduced and simpli­

fied. This locality is another 400 miles or so to the southwest of

owstoni, and is nearly at the southwestern limit of the species. At

about this point, the broadleafed deciduous (primarily oak) forest

occupied by S_. davidianus gives way to the montane coniferous forest

occupied by the little-known species S. (Rupestes) forresti (Moore and

Tate 1965:306). 49

c?

c?

Fig. 6. Baubella of Sciurotamias davidianus.

All 13x, dorsal (left) and right lateral views. Top, S_. .d. davidi­ anus (AMNH 45305). Center, two jS. cL owstoni (AMNH 27546, 27547). Bottom, three S_. d.. consobrinus (AMNH 111363, 111367, 111372). 50

This trend toward reduction of the ossa genitalia suggests that

Sciurotamias may have affinities with Tamiasciurus, as Moore (1959)

hypothesized, as well as with the chipmunks. As previously noted,

however (Chapter 3), secondary reduction or loss of this bone has

occurred independently in a number of mammalian taxa. Also, the number

of transbullar septa apparently can vary without extensive reorganiza­

tion of the genome, for 1% of all Tamias examined by Moore (1959) had

three septa (the modal number for Tamias is two). The evidence linking

Sciurotamias with Tamiasciurus—reduction of ossa genitalia, and septum

count—is therefore more equivocal than that linking it with the

Tamiina. Sciurotamias may well be related to both groups; Long and

Captain (1974) noted that the forefeet of Tamias, Eutamias, Tamia­

sciurus , and Sciurotamias are similar to one another and different

from those of either the tree squirrels or the ground squirrels, and

some of the vestigial Tamiasciurus bacula illustrated by Layne (1952)

reveal a trace of a constriction proximal to the tip.

Characters that Sciurotamias shares with the Tamiina, but not

with Tamiasciurus, include the flattened braincase, opisthodont upper

incisors, fur-lined cheek pouches, and certain details of pelage color­

ation. S_. davidianus has a tricolored ear quite like that of most

Nearctic Eutamias: the pinna is blackish with a white posterior border

and white postauricular patch, while the anterior border bears gold-

tipped hairs which are continuous with an indistinct gold eyestripe

(pers. obs.). The tail of this species, although slightly bushier, is

otherwise exactly like that of Eutamias as described by D. F. Johnson: There is no underfur on the tail; all the hairs are long and mod­ erately coarse. They are reddish or yellowish at the base. On the hairs of the underside of the tail this color is continued to the tip. The hairs on the sides and upper parts of the tail each have a broad subterminal band of black and a white or buffy tip . . . (which) give the tail a frosted appearance and a definite edging along the sides(1943:67).

The tips of these hairs are white in JS. davidianus, and the

ventral surface of the tail is dull yellowish. I have not had the op­

portunity to examine specimens of S_. forresti, but it is reported to

have a chipmunk-like lateral stripe on the body (Moore and Tate 1965).

All these markings could have arisen independently, of course, but in

view of the tamiine os genitale, convergence seems an unlikely ex­

planation.

In conclusion, Sciurotamias appears to be essentially a large

aberrant chipmunk, and it should be included with the subtribe Tamiina

of the tribe Marmotini. Sciurotamias could be placed in a separate subtribe within the Marmotini; but the Tamiina will soon include only one genus (previous section), and the Marmotina already includes only one genus, and it seems pointless to erect a new subtribe for every genus.

It is difficult to decide whether Tamias (sensu lato) or

Sciurotamias is more ancient, for the latter has some derivative char­ acters (loss of one pair of mammae; reduction of ossa genitalia; reduc­ tion of ectopterygoid ridge of alisphenoid), while in certain cranial characters it resembles the ancestral sciurids. As a group, the (recon­ stituted) Tamiina appear to be the most ancient of living squirrels. CHAPTER 5

STATUS OF THE GUAYMAS CHIPMUNK POPULATION

The creature . . . made swiftly off across the open plains and vanished from the saint's wondering eyes. And indeed whether the devil had assumed this shape to terrify him, or whether (as might well be) the desert that breeds monstrous beasts begat this creature also, we have no certain knowledge.

St. Jerome, The Life of St. Paul the First Hermit (ca. 378 A.D.)

W. J. Schaldach, Jr., and P. Bloedel (pers. comm.) collected

chipmunks near Guaymas, Sonora, in December 1956. The specimens have disappeared, but the Arizona-Sonora Desert Museum has a record of

their accession (C. Hanson, pers. comm.).

To my knowledge, the first extant specimens were taken by A.

L. Gardner in 1960 and were deposited in the Los Angeles County Museum.

Loomis and Stephens (1965) collected one specimen in 1962; in that same year, R. Davis and several associates became interested in determining the origin and affinities of these chipmunks. By 1975 a total of 24 were available, and it was possible to characterize the population adequately (Callahan and Davis 1977). Brief ecological and behavioral accounts have also been published (Dunford and Davis 1975, Callahan and Davis 1976).

Findley (1969:115) apparently had this population in mind when he wrote that dorsalis "may, under suitable circumstances, occur nearly

52 53

to sea level in the Sonoran desert." I have found no other published

account of the coastal Sonoran chipmunks; indeed, few mammalogists—

even those whose research interests include Eutamias and/or Sonora—

seem aware of their existence. As recently as 1974, the curator of one

large California museum declared himself "mystified" at my expectation

of finding chipmunks in coastal Sonora.

Morphological and behavioral evidence (R. A. Brown 1972;

Callahan 1975; Dunford and Davis 1975) indicates that this population

is allied with Eutamias dorsalis rather than with the chipmunks of Baja

California. However, I contest Loomis' and Stephens' C1965} tentative

assignment of the population to IS. _d. dorsalis. In this section I will show that the coastal Sonoran chipmunks constitute a clearly differen­

tiated subspecies.

The range of IS. d_. dorsalis extends from the Grand Canyon in

Arizona to northwestern Durango (Hall and Kelson 1959). Specimens from

the southern pare of this range tend to be larger and more distinctly striped than are those from the north; indeed, those from the extreme south were originally described as a separate species,-IS. canescens

(Allen 1904), now regarded as a synonym of IS. dorsalis (Howell 1929).

Because the Guaymas chipmunks are small, I have compared them statisti­ cally with the small "northern" rather than with the large "southern" form of E. d.. dorsalis, even though their zoogeographic affinities are probably with the latter. Cranial and external measurements of IS. <1. dorsalis from Chihuahua and Durango are given by Lidicker (1960) and

Allen (1904) respectively. 54

Eutamias dorsalis sonoriensis, new subspecies

Guaymas Chipmunk

Description

Holotype. Adult male, skin, skull, and stained baculum; no.

398643, USNM; from mountains near Maytorena, 330' el,, ca. 15 mi NE of

Guaymas, Sonora, Mexico; collected by J. R. Callahan on 13 November

1973; original number 123. Measurements (abbreviations, Chapter 2)

are GLS 35.7; EL 12.8; MTR 5.6; LN 10.5; CD 13.7; ZB 19.5; LIB 8.0;

CB 16.8; RB 8.8; WN 2.4; HB 117.0; TV 98.0; RHF 35,0; EN 22.0; BL 5.0;

BS 4.2; BA 130°.

Topotypes. UA 10023, 10025, 19097, 19100 (adult males); UA

19096, 19098, 19099, 20980 (adult females); UA 10024 (subadult fe­

male).

Paratypes. From San Carlos Bay and vicinity, LACM 13308,

CSLB 4171, UA 19913, 22841, 23169 (adult males); LACM 13306, 13307,

13309, UA 22842, 23168 (adult females); UA 19932 (subadult female).

Appendix B indicates the range of variation in the adult topotypes and

paratypes.

Diagnosis. Skull smaller and narrower than in other subspecies

of _E. dorsalis, but with relatively broad rostrum. Body smaller than

15. _d. dorsalis, but tail relatively long. Baculum (Figure 7) longer

than in IS. d_. dorsalis (including Chihuahua and Durango specimens) or

J5. _d. utahensis (White 1953b); compared with E_. d_. dorsalis, t = 6.68,

IP < .0001; d/s = 3.2, P_ = .05. Baculum similar in length to that of 55

b

c

d

Fig. 7. Ossa genitalia of Eutamias dorsalis.

All right lateral view (scale = 1 mm): a, E, d^. dorsalis baculum (field no. 3). b, J^. d_. sonoriensis baculum (holotype; USNM 398643). c> J±. -4* dorsalis baubellum (UA 12088). d, E., d_. sonoriensis baubel- lum (UA 22842). .E.

Chihuahua (Lldicker 1960). Baubellum of female sonoriensis longer than

that of 12. ji. dorsalis (t = 5.26, £ <• .0001). The divided base and

ventral spur shown in Fig. 7d are typical of the sonoriensis baubellum

but rare in dorsalis (X^ = 10.78, P_ < .025).

As shown in Fig. 8, sonoriensis and dorsalis are 100% separable

by discriminant analysis using cranial and external measurements only

(Wilks' Lambda statistic = .11613, 1? < .0001). LBC, a sexually di­

morphic character in 13. ji. dorsalis (t = 4.41, P_ * .001), was excluded from the discriminant to avoid the necessity of dividing the relatively

small sample of 20 adult sonoriensis. Much of the separation is due to

characters that reflect skull width (Table 2).

The karyotype of one specimen examined (Fig. 9) was B of Sutton

and Nadler (1969). The spermatozoan is shown in Fig. 3b.

Distribution (Fig. 10). On the basis of available specimens, the southern'limit of the range appears to be the south end of San

Carlos Bay. S. Buskirk observed chipmunks in the mountains just north of Guaymas (R. Davis, pers. comm.), but no specimens were taken there.

South of Guaymas, the coastal habitat appears unsuitable for chipmunks.

The Gulf of California constitutes the western limit, no chipmunks having been reported from any of the islands in the Gulf. The type locality is very tentatively regarded as the eastern limit.

In January 1969, B. Spicer photographed chipmunks on the coast

18 miles northwest of Punta Doble; this locality is represented by an open circle in Fig. 10. E. L. Roth (pers. comm.) observed chipmunks at 57

10

O* 8i cr3 6 O 4J

J=.

score

Fig. 8. Linear discriminant scores: Eutamias dorsalis sonorlensis Cshaded) and E. d. dorsalis. 58

TABLE 2. Linear discriminant coefficients: Eutamias dorsalis sonori- ensis vs. E. d. dorsalis.

GLS -1.68669

EL .90853

MTR .83646

LN - .16074

ZB .04368

CD 1.26462

LIB .72480

CB 2.28062

RB - .69676

WN - .67518

HB - .30419

TV - .09873

RHF - .59934 59

I g K X & «

a A i & i « A fi • A

I H A ft « a

s X Y « a « '• ">

Fig. 9. Karyotype of a male Eutamias dorsalis gonorlensis (holotype; USNM 398643). 60

50 100 mi

Fig. 10. Distribution of Eutamias dorsalis in Sonora, Mexico.

Circle = 35. d_. sonoriensis (open circle = photographic record; see text), ? = unconfirmed sight record, triangle = E. cL dorsalis (Burt 1938; W. Caire, pers. comm.). Range of 12. d_. dorsalis after Ander­ son (1972). 61

San Pedro Bay and vicinity in fall 1975. The northern limit of sonor-

iensis has not been determined, but there is no obvious barrier to its

dispersal at least as far north as Kino Bay. Thor Heyerdahl (1972:49) refers to chipmunks on the Sonoran coast just opposite the northern tip of Isla Tiburon, and in a letter he verifies that the animals appeared

to be Eutamias rather than Ammospermophilus (both of which may popularly be called "chipmunks"). Other unconfirmed sight records are indicated in Fig. 10.

Ecological Notes

Habitat. Dominant plant and vertebrate species at the sonorien- sis type locality are listed in Tables 3 and 4. Cockrum and Bradshaw

(1963) provide further ecological information on the Maytorena and San

Carlos Bay areas. Loomis and Stephens (1965) note that their specimen was found "at the base of a large rock outcropping near a small, water- filled pothole", and W. J. Schaldach (pers. comm.) observed and collected sonoriensis only in those arroyos containing Washingtonia palms and permanent water. F. Wiseman (pers. comm.) observed sonoriensis at

Nacopuli Canyon (near San Carlos Bay) in association with palms, figs, and sedges, near standing water. There is no permanent surface water at the type locality, however, and according to R. Davis and S. L.

Lindstedt (pers. comm.) there is no (fresh) water near many of the collection sites in the San Carlos Bay region.

Behavior. In general the behavior of sonoriensis is similar to that of other 13. dorsalis. It nests, takes refuge, and caches food in rock crevices and in burrows among the boulders on talus slopes. Its 62

TABLE 3. Common plant species at the type locality of Eutamias dor- salis sonoriensis.

Vernacular names, if available, are provided for convenience.

Acacia willardiana (Acacia)

Bursera laxiflora

Bursera microphylla (Copal)

Carnegiea gigantea (Saguaro)

Cercidium microphyllum (Paloverde)

Fouquieria diguetii (Ocotillo)

Guaiacum coulteri

Haematoxylon brasiletto

Jatropha cuneata

Lemairocereus thurberi (Organpipe)

Olneya tesota (Ironwood)

Prosopis juliflora (Mesquite)

Ruellia californica TABLE 4. Some common vertebrate species at the type locality of Eutamias dorsalis sonoriensis.

Sauromalus obesus (Chuckwalla) Uta stansburiana (Side-blotched Lizard) Cnemidophorus burti (Giant Spotted Whiptail)

Buteo jamaicensis (Red-tailed Hawk) Cathartes aura (Turkey Vulture) Lophortyx gambelii (Gambel's Quail) Columbigallina passerina (Ground Dove) Zenaida asiatica (White-winged Dove) Geococcyx californianus (Roadrunner) Bubo virginianus (Great Horned Owl) Calypte costae (Costa's Hummingbird) Cynanthus latirostris (Broad-billed Hummingbird) Centurus uropygialis (Gila Woodpecker) Colaptes aufatus (Common Flicker) Dendrocopos scalaris (Ladder-backed Woodpecker) Myiarchus cinerascens (Ash-throated Flycatcher) Auriparus flaviceps (Verdin) Campylorhynchus brunneicapillus (Cactus Wren) Catherpes mexicanus (Canyon Wren) Salplnctes obsoletus (Rock Wren) Toxostoma curvirostre (Curve-billed Thrasher) Polioptila melanura (Black-tailed Gnatcatcher) Lanius ludovicianus (Loggerhead Shrike) Molothrus ater (Brown-headed Cowbird) Almophila carpalis (Rufous-winged Sparrow) Amphispiza bilineata (Black-throated Sparrow) Carpodacus mexicanus (House Finch) Pipilo fuscus (Brown Towhee) Richmondena cardinalis (Cardinal)

Macrotus californlcus (Leafnose Bat) Spilogale gracilis (Spotted Skunk) Canis latrans (Coyote) Urocyon cinereoargenteus (Gray Fox) Lynx rufus (Bobcat) Ammospermophilus harrisi (Harris Ground Squirrel) Cltellus variegatus (Rock Squirrel) Neotoma albigula (White-throated Woodrat) Peromyscus eremicus (Cactus Mouse) Sylvilagus auduboni (Desert Cottontail) i

64

vocalizations seem identical to those of _E. d_. dorsalis (Dunford and

Davis 1975).

Food and water. These chipmunks are known to feed on the fruits

of organpipe, saguaro, and copal, and on the flowers of ocotillo (see

Table 3). Thus succulent vegetation, when available, is probably their

most important water source. I observed one individual gnawing on buds

of Jatropha in November 1973 during a period of very hot and dry weath­

er when no cactus fruits were available. I snapped off a few of these

buds and found that each exuded a large drop of fluid. However, I was

unable to see whether the chipmunk was eating the buds themselves or

merely gnawing them and lapping the juice.

Another probable source of water is dew. Hart (1971) believed

that dew is an important water source for JE. dorsalis in northern Utah,

and certain other sciurids are known to use dew (Linsdale 1946, Henisch

and Henisch 1970; see also Chapter 6). High atmospheric humidity and

heavy dews are characteristic of the Guaymas area.

Predators and parasites. F. Wiseman (pers, comm.) found a

sonoriensis being swallowed by a boa, Constrictor constrictor, at

Nacopuli Canyon in August 1975. For other potential predators see

Table 4. Anderson and Ogilvie (1957) found chipmunk remains, believed

to be those of E. dorsalis, in owl pellets from northeastern Chihuahua.

Some ectoparasites of sonoriensis are mentioned by Loomis and Stephens

(1965).

Reproduction. E^. _d. sonoriensis apparently breeds about six to

eight weeks earlier in the year than does the montane E. d. dorsalis population studied by Dunford (1974) in the Santa Catalina Mountains of

Arizona. However, dorsalis in the foothills of the Santa Catalinas

breeds as early as sonoriensis; on 31 March 1976 I observed a juvenile

dorsalis, approximately five to six weeks old, near Molino Canyon (3900').

This appears to be a seasonal record for the species (see Hoffmeister

1971:102), and it implies copulation in late January unless female chip­

munks are capable of delayed fertilization or implantation. Dunford

(1974:411) notes that several species of Eutamias tend to breed earlier

at lower elevations.

Desert adaptations. S. L. Lindstedt (Univ. of Arizona; unpub­

lished) found that the relative medullary thickness of the kidney is sig­

nificantly greater in sonoriensis than in montane 15. dorsalis, indicating

a greater ability to reduce urinary water loss. Willems (1971) similarly

reported that the KMT of IS. minimus from semiarid sagebrush habitat is

greater than that of montane populations of the same species.

Other apparent desert adaptations of sonoriensis include the

small body size and relatively long tail, which are in accordance with

Bergmann's and Allen's rules (Mayr 1970). In theory these modifications

should influence heat exchange with the environment by increasing surface

area in relation to body volume (Schmidt-Nielsen 1972). Of particular

interest is the fact that the skull is relatively, as well as absolutely,

narrower in E_. _d. sonoriensis than in E_. d_. dorsalis. The same appears

to be true of the desert-dwelling E_. obscurus meridionalis as compared

with montane populations of the same species (Chapter 6). A relatively

narrow skull has been shown to facilitate heat loss in desert endotherms

(Niles 1973). 66

My field observations, and those of R. Davis, indicate that sonoriensis largely avoids the stresses of its environment by remaining in its (presumed) burrows between about 0900 and 1700. Lindstedt similarly found some indication of a bimodal activity rhythm in caged specimens; he also notes, however, that during May 1970 chipmunks at San

Carlos Bay were active from dawn until dusk. Even at midday, some indi­ viduals were active on rocks with surface temperatures of 55 to 60° C.

Zoogeographic Affinities

There has been some speculation that chipmunks may recently have been introduced to the San Carlos Bay area (B. Hayward, pers. comm.), for it seems odd that Burt (1938) would have overlooked these animals. On the other hand, there is no evidence of deliberate introduction, and it seems unlikely that a few escaped pets could establish themselves success­ fully in the desert.

The inland canyon populations could easily escape the notice of collectors, and it may be that agricultural activity has allowed the dispersal of chipmunks to the more accessible coastal areas only in recent years. I discount the possibility that the inland canyon popu­ lations themselves have been introduced. Two montane reptiles—Diadophis punctatus and Gerrhonotus kingi—also occur unexpectedly in the Guaymas area, suggesting that a woodland corridor may formerly have extended westward from the Sierra Madre (M. D. Robinson, pers. comm.; see also

Chapter 7). Also, the degree of morphological specialization exhibited by the Guaymas chipmunks (particularly by the inland canyon specimens) argues against recent introduction. The relative roles of ecophenotypic vs. genetic variation are unknown here, but are universally ignored in studies of this kind. CHAPTER 6

STATUS OF THE EUTAMIAS OBSCURUS COMPLEX

En el arroyo seco se ciernen sus gritas A1 pie del penasco pintado Por los indios antiguos, con el duende rayado: Por aca se avanzo el arbolado, Y por allS. se refluyd, cantan las mostelitas: Esperamos la redencion cfclica . . .

Vision de la Navidad (1973)

I have been unable to determine just how or why obscurus became

a subspecies of Eutamias merriami in the first place. G. Miller and Rehn

(1901) list the northern Baja California population as Eutamias obscurus,

following Allen (1890), but Nelson and Goldman (1909) refer to it as

"IS. m. obscurus." The synonymies compiled by Howell (1929) and sub­

sequent reviewers of the genus invariably list Nelson and Goldman (1909)

as the first authors to include obscurus with E^. -merriami.

Callahan (1975) reported that IS. merriami meridionalis and 15. m.

•merriami differ in several taxonomic characters, most notably the karyo­

type and the structure of the ossa genitalia. 15. m. obscurus was found

to have the same type of baculum as meridionalis, and because the name

obscurus (Allen 1890) has priority over meridionalis (Nelson and Goldman

1909), both Baja California forms were tentatively regarded as sub­

species of Eutamias obscurus. Further evidence for the specific dis­

tinctness of IS. obscurus was provided by a series of specimens (MVZ

68 ! i |:

69

39083-39085) collected In Baja California just south of the California

border and including typical representatives of both 15. obscurus and

12. merriami (Callahan 1977).

The matter was complicated by the discovery that JE. obscurus

occurs not only in Mexico, but also in the Transverse and Peninsular

Ranges of southern California (Callahan 1977). Thus it was necessary

to collect in several more areas of potential intergradation between the

two presumptive species. Furthermore, the IS. merriami holotype is from

the San Bernardino Mountains, where both species occur; if the holotype

belonged in fact to the southern species, then this species would become

15. merriami (Allen 1889) and the northern species would become IS. pricei

(Allen 1895).

As explained in the species accounts below, I was able to confirm

that the two forms do not intergrade and that the JE. merriami holotype

belongs to the northern species.

Howell (1922) made Eutamias durangae (Allen 1903) a subspecies of

JE. bulleri (Allen 1889). No reason was offered for the change of status;

indeed, Howell (1929:104) later remarked that "Although there is appar­

ently no barrier between the range of this race and that of bulleri there

is a striking difference between the two forms in coloration." Fleharty

(1960) also noted a marked difference between the bacula of the two al­

leged subspecies.

Baker and Greer (1962:83) believed that JS. b^. bulleri and IS. b_.

durangae are geographically isolated by the canyon of the Rfo Mezquital-

Rio San Pedro, considered to be an important zoogeographic barrier in i ; ! ' i i j i

70

; Durango. However, at least two of their specimens (MSU 3331 and 3332;

see Fig. lb), collected north of this barrier and listed by them as E.

£> durangae, proved on examination to be typical J2. b^. bulleri in all

respects. I visited southern Durango in May 1974 and 1976 in order to

confirm that bulleri and durangae are not geographically isolated and to

obtain ecological data and live specimens for karyotypic analysis.

The problem of holotype identification did not arise in this

case, as in the case of jE. merriami, because the type localities of

bulleri and durangae are not near the zone of contact (Fig. 26, p. 126).

However, a comparison of the ossa genitalia and other taxonomic charac­

ters (see species accounts) indicates that durangae, and also the iso­

lated Coahuilan form solivagus, belong with IS. canipes (Bailey). Because

the name canipes (Bailey 1902) has priority over both durangae (Allen

1903) and solivagus (Howell 1922), the latter two taxa become subspecies

of _E. canipes.

Eutamias merriami (Allen, sensu strictu)

Merriam's Chipmunk

(Synonymy under Subspecies)

General Characters

A large, grayish- or yellowish-brown chipmunk with rather in­

distinct dorsal and dorsolateral stripes and small, indistinct or obso­

lescent postauricular patches. Tail bushy and long in proportion to

body. Ears relatively long and narrow, not sharply bicolored. Little

or no sex dimorphism. Skull large and moderately flattened. Upper

incisor recurvature variable and not diagnostic, despite Hall and Kelson 71

(1959:309). Ossa genitalia as shown in Fig. 11. Karyotype is B of

Sutton and Nadler (1969). Spermatozoa as in Fig. 3c.

Comparisons

J5. merriami may occur sympatrically with any of eight other chipmunk species: IS. minimus, E_. amoenus, _E. sen ex, 15. quadrimaculatus,

15. panamintinus, E. umbrinus, 15. speciosus, and E.-obscurus (Hall and

Kelson 1959; Johnson 19A3; Sutton and Nadler 1974; Callahan 1977). The first two listed have bacula generally similar to that of merriami but with shorter shafts (White 1953b); both species are much smaller and more distinctly striped than merriami. The remaining species have bacula quite unlike that of merriami (White 1953b; Sutton and Nadler 1974; Figs.

15, p. 93, and 16, p. 94). For further comparison with j2. speciosus and

.E. obscurus see the 13. m. merriami account.

Geographic Variation

Three subspecies are currently recognized within E_. merriami. As

Johnson (1943) points out, color variation appears to follow Gloger's Rule

(Mayr 1970:200). Thus the darker populations (pricei) occupy humid coast­ al areas from San Francisco Bay southward, while the palest form (kernen- sis) is restricted to the semiarid Kern Basin and the eastern slope of the Sierra Nevada. The pale kernensis-like coloring appears also in some _E. m. merriami from the desert slope of the San Gabriel Mountains, and in the sibling species 15. obscurus; aridity appears to be the com­ mon denominator. None of the three named forms is geographically iso­ lated (Fig. 14, p. 82). According to Johnson (1943), color intergrada- tion between pricei and merriami occurs over an area several times as 72

O 1 2 3 mm

Fig. 11. Ossa genitalia of Eutamias-merriami.

All right lateral view: a, IS. m. merriami baculum (SD 23251), b, E. m. pricei baculum (CP 8-3). c, E_. m. kernensis baculum (MVZ 15029; topotype). d, IS. m. merriami baubellum (AMNH 1158; topotype) e, J5. m. pricei baubellum (MVZ 6154). 73 great as the entire range of price!. Therefore pricei represents one end of a shift cline (Smith and Cuellar 1972), and does not qualify as a subspecies by modern standards (Whitaker 1970).

The extreme form of pricei differs from merriami in two quanti­ tative characters: CD (t = 6.03, £ < .0001) and TV (t = 3.18, £ < .001).

I found no significant single-character differences between merriami and kernensis (see Appendix B). Miller and Stebbins (1964:291) similar­ ly noted that these two subspecies do not differ quantitatively, citing

Johnson's (1943:129) figures. Interestingly, Johnson (1943:135) cited these same figures as evidence that the two forms are very different.

Respectable proportions of all three subspecies were classified correctly by discriminant analysis (Fig. 12), despite the extensive overlap in single characters; a similarly paradoxical situation is dis­ cussed by Jolicoeur (1959). However, the sample mean vectors of male kernensis and merriami do not differ significantly (Milks' Lambda =

.48935, J? = .091). It is difficult to believe that the minute quanti­ tative differences separating kernensis from merriami are biologically significant, particularly in the absence of geographic isolation.

Although character variation in E^. merriami does not lend itself to "pigeonholing" (Mayr 1970), it may be interpreted in other ways. The ecological correlates of color variation were previously mentioned. The biological significance of cranial depth is unknown (Chapter 3), but tail length is known to follow Allen's Rule in other chipmunk species.

The desert forms have relatively long tails (p. 65), and data taken from

Howell (1929) and from the present study reveal that tail length in the 74

a. merriami pricei

b.

cr

11 c. kernensis

d.

-« -2 SCORE

Fig. 12. Linear discriminant scores: Eutamias merriami merriami, E_. m. pricei, and _E. m. kernensis. a-b, E. m. merriami vs. JE. m. pricei. c-d, _E. m. merriami vs. 12. m. kernensis. Symbols refer to all four graphs unless otherwise indicated. 75

genus as a whole is related to climate. The mean ratio of TV to total

(TV + HB) length of the three Eutamias subspecies occupying the Hudson-

ian life zone is .43; of 31 occupying the Canadian zone, .44; of 33

occupying the Transition zone, .45; of 11 occupying the Upper Sonoran

zone, .46; and of the two occupying the Lower Sonoran zone, .47.

I have therefore analyzed variation in tail length of E_. merriarai

in relation to three factors: latitude, altitude, and subspecies (the

latter represented by dummy variables; Draper and Smith 1966:134). Many

other environmental factors might be included in the model, but habitat

notes were unavailable for the majority of specimens examined.

TV is not correlated with latitude (r = .13, £ > .10) but is

fairly strongly correlated with altitude (r = .42, £ < .0001). This

correlation seems remarkably high, for undoubtedly it is obscured by

individual variation in measurement techniques among the dozens of col­

lectors who recorded the measurements (Simpson, Roe and Lewontin 1960: 2 22). R for the multiple regression of TV on altitude and subspecies

(Table 5) is .22 (P < .0001); the contributions of altitude and of sub­

species are .12 and .10 respectively. Thus it appears that ecotypic var­

iation in tail length is characteristic of-_E. mer-riami.

Thorington (1966:121) postulated that "the normal amount of hair

on the tail of a rodent is indicative of the importance of the role of

the tail of the animal in dissipation of heat to the environment", be­

cause hair on the tail (of Glis glis) significantly reduced heat loss.

Tail length evidently has some biological significance in IS. merriami,

and the correlation with altitude suggests that the tail is involved in

thermoregulation; yet this species has perhaps the bushiest tail of any TABLE 5. Analysis of variance: tail length of Eutamias merriami.

Source d.f. SS MS

Total 128 7324.4

Regression 4 1593.4322 398.3580

Altitude alone 1 1310.0272 1310.0272 27.663**

"Residual" 127 6014.3728 47.3573

Subspecies after altitude 3 283.4050 94.4683 2.044

Subspecies alone 3 1237.7 412.5667 8.473**

"Residual" 125 6086.7 48.6936

Altitude after subspecies 1 355.7322 355.7322 7.697**

Residual 124 5730.9678 46.2175

R^ due to altitude alone = .18 (P < .0001)

due to subspecies alone = .17 (P < .0001)

R^ due to altitude and subspecies = .22 (P < .0001) 77

chipmunk (except Sciurotamias). Tails serve other than thermoregulatory

functions, of course. Long distichous tails are believed to aid arboreal

rodents in balancing (Thorington 1966), a factor that may partly explain

the tail characteristics of 13. merriami. These chipmunks spend a good

deal of time climbing shrubs and trees, often hanging precariously up­ side down from slender twigs. But this explanation does not account for the correlation of tail length with altitude, for the species climbs at all altitudes.

Bailey (1931:93) noted that 15. merriami, and also JE. dorsalis,

exhibit at times a "slow, serpentine waving" of the uplifted tail (not

to be confused with the tail-jerk which accompanies the alarm call). I have observed that merriami may sit in the shade for 30 minutes or longer performing these movements, which apparently are accompanied by

piloerection of the tail, and I strongly suspect that they are dumping heat. Thorington (1966:87) showed that the rate of heat loss of a furred tail increases with the rate of air flow, although this increase is even greater if the tail is hairless.

These chipmunks need fur on their tails for climbing purposes

(and perhaps for insulation, for they do not hibernate in winter), yet they sometimes occupy very hot environments. Increasing the length (and thus the surface area) of the tail at low altitudes, and performing movements favoring heat loss, would appear to be a reasonable compromise.

It is interesting that male Asian chipmunks (E_. sibiricus) per­ form apparently identical tail movements, even including piloerection, as a courtship display (Dobroruka 1972). Examples of courtship displays derived from maintenance behavior are common in the ethological 78

literature (Eibl-Eibesfeldt 1970:108). In E_. merriami and E. dorsalis

this behavior seems unrelated to reproduction, and at least in merriami

it is performed by both sexes. An entirely different tail movement,

consisting of a rapid vibration, may be performed by male eastern chip­

munks (Tamias striatus) during courtship (Dunford 1972).

Subspecies

Eutamias merriami merriami (Allen)

Tamias asiaticus merriami. Allen 1889:176.

Tamias merriami. Allen 1890:60.

Eutamias merriami. Merriam 1897:197.

Eutamias merriami merriami. Miller 1912:310.

Eutamias merriami mariposae. Grinnell and Storer 1916:4.

Holotype: Adult female, skin and skull, no. 1157/728, AMNH; from San Bernardino Mountains, California, 4500', due north of San

Bernardino, according to Howell (1929:123); collected by F. Stephens on 13 June 1887; original number 482. Measurements provided by Dr.

Sydney Anderson are GLS 40.6; LN 13.3; ZB 21.05; LIB 9.2; CD 16.1; HB

140 (5.5 in.); TV 122 (4.8 in.). Note: the CD measurement may not be comparable to values given in Appendix B.

Topotype examined: AMNH 1158 (adult female, skin and stained baubellum).

Diagnosis: Sexes similar, female exceeding male only in LN (t =

3.11, £ < .005) and RHF (t = 3.04, P_ * .005). Coloration variable: generally beige, often with a yellow tinge but sometimes grayish. 79

Stripes usually dark brown, the mid-dorsal one often partly black; very rarely, all body stripes black or reddish. Winter pelage similar but duller. North of San Gorgonio Pass, throat region usually grayish due to black band at base of hairs. South of this barrier, hairs of throat typically white to base.

From 15. speciosus, distinguished by longer, proportionately nar­ rower and more flattened cranium, more recurved upper incisors (a use­ ful character in this instance), longer tail, and different coloration: speciosus has a conspicuous white dorsolateral stripe and sharply bi- colored pinnae.

From 12. obscurus, distinguished by larger size, longer tail and hind foot, and larger, less flattened cranium. These differences are less pronounced in the San Bernardino Mountains than in other zones of sympatry (see Chapter 7); however, the two species are 100% separable by discriminant analysis of skull and body measurements (Fig. 13, Table

6). Wilks' Lambda = .01592 for males, .07473 for females (£ < .0001 for both).

The os genitale (the best diagnostic character) was not pre­ served with the merriami holotype, and I have not had the opportunity to examine the skin and skull, which are at the American Museum. The type locality as stated by Howell (1929:123) is about 20 miles outside the known range of 12. obscurus (Fig. 14); however, Howell also gives a different altitude (4500' vs. 7000') and collection date (June 13 vs.

June 10) than does Allen (1889). Presumably, Howell had access to the collector's journal or other information, because he adds that the 80

13- 10 8 A

4- females >. g4 <0 J=.

a

males

ID- 10 score

Fig. 13. Linear discriminant scores: Eutamias obscurus davisi (shaded) and E. merriami merriami. 81

TABLE 6. Linear discriminant coefficients: Eutamias merriami merriami vs. E. obscurus davisi.

males females

GLS 34.20059 -10.84034

RL -18.42694 6.71143

LBC -22.35900 6.59522

MTR .11339 - .10027

LN - 1.27885 - .39209

ZB 1.02733 - .56472

CD .43465 - .00314

LIB .16869 - .25169

CB - .17060 - .26891

RB - .26059 .06663

WN .10926 .02889

HB .19614 - .95843

TV - .03687 .04441

RHF .06029 2.77642 82

Fig. 14. Geographic distribution of Eutamias obscurus and 33, merriami.

Stippled pattern = 13. merriami; striped pattern = E_. obscurus. Type localities indicated by dots: from north to south, 12. m. merriami, jE. obscurus davisi, 13. jo. obscurus, and JE. o_. meridionalis. Type locali­ ties are not shown here for E. in. pricei or for 12. m. kernensis, but the ranges are set off by lines; see text. ? = unconfirmed record. 83 specimen was taken due north of the city of San Bernardino, a fact not recorded by Allen (1889). But it is also possible that Howell simply made a mistake, so the locality alone is not adequate grounds for iden­ tification.

The holotype cannot be plugged into the discriminant (Table 6), because not all measurements are available. However, on the basis of tail length alone, the hypothesis that the holotype belongs to E_. ob- scurus is rejected at the .0001 level (t = 4.75). On the basis of GLS alone, the hypothesis is rejected at the .001 level (t = 4.25). Also, the coloration of the holotype as described by Allen (1889) and by S.

Anderson (pers. comm.) is typical of 13. merriami (sensu strictu). The slight remaining uncertainty does not warrant designation of a neotype.

Distribution (Fig. 14): Collected in the Coast and Diablo ranges from southern Santa Cruz Co., California, to Ventura Co.; on the west slope of the Sierra Nevada from Columbia, Tuolumne Co., south to Tulare

Co.; from Mt. Pinos through the San Gabriel, San Bernardino, and San

Jacinto Mountains; in San Diego Co., from Mt. Palomar south through the Cuyamaca and Laguna Mountains to the north end of Nachoguero Valley, just outside the U.S. boundary in Baja California del Norte. Absent from apparently suitable habitat in the Santa Ana range; in the foot­ hills of the Sierra Nevada north of Columbia; and in the vicinity of

Mt. Diablo (Johnson 1943).

Recorded at altitudes ranging from near sea level (7 mi W of

Gaviota, Santa Barbara Co.) to 8600' (Wildhorse Meadow, San Bernardino

Mountains). 84

Ecological notes: (1) Habitat. This subspecies apparently is

restricted to chaparral (particularly Arctostaphylos) throughout its

range, usually in association with oaks and/or pines. It is also re­

ported to occupy the pinon-juniper belt on the desert slope of the San

Gabriel Mountains (Vaughan 1954), but I found no chipmunks there in

May 1976.

The range of merriami overlaps that of ]£. obscurus at several

localities. In the San Bernardino Mountains, the two species meet just

north of Big Bear Lake at approximately 7000', where the Upper Sonoran

pinon-juniper woodland occupied exclusively by E." obscurus gives way to

the yellow pine (Pinus ponderosa) and white fir (Abies concolor) which

characterize the Transition life zone (see also Grinnell 1908). The

two species also meet on the desert slope of Sugarloaf Mountain in the

vicinity of Wildhorse Meadow (8500'-8600'). Grinnell (1908:18) noted

that this slope is "largely Upper Sonoran in spite of the high altitude;

for this is on the side influenced by the desert air currents . , .",

and I found E. merriami only above 8600' there, approximately where the

first white firs are seen.

On the Pacific slope of the San Bernardino Mountains, where 12.

obscurus does not occur, JE. merriami occupies both the Upper Sonoran

(Quercus kelloggii-Pinus coulteri) and Transition zones.

In the San Jacinto Mountains, merriami is largely restricted to

chaparral associated with oak-pine woodland. In the foothills south of

Banning, the species is common in fairly arid chaparral (Adenostoma

fasciculatum, Arctostaphylos sp., Quercus dumosa) with only scattered live oaks (Q. chrysolepis). On San Jacinto Peak at elevations above 5500', however, JE. merriaml is replaced by 12. obscurus—ail unexpected

reversal of zonation from that found in the San Bernardino Mountains.

Competitive exclusion is also suggested by the fact that merriami occurs

up to the summit of Thomas Mountain (6800'), an isolated peak not oc­

cupied by E. obscurus. However, merriami is scarce on Thomas Mountain

above about 6000', where the dense chaparral is replaced by more open

pine-fir forest. Within this Transition-zone "island" (which has an

area of less than 2 mi^) I collected only one chipmunk, an immature

merriami (UA 23296); its cheek pouches were filled with peanuts, suggest­

ing that it may have been attracted away from its usual chaparral habitat

by the refuse at the summit campground area. Thus the habitat occupied

by _E. obscurus elsewhere in the San Jacinto Mountains (and by IS. merriami

itself, in the San Bernardino Mountains) may be essentially vacant here.

In the relatively arid Santa Rosa Mountains to the southeast,

obscurus replaces merriami at all elevations, even in dense chaparral

that appears structurally suitable for the latter species (but dominated

by Adenostoma, which seems to provide a less favorable habitat than

Arctostaphylos). The eastern limit of IS. merriami may be determined by

aridity rather than by interspecific aggression (see Heller 1970). All zones of overlap between IS. merriami and JS. obscurus are quite narrow, but the mechanism(s) by which the two species maintain this segregation has not yet been determined.

E. merriami is the only chipmunk present in the mountains of

San Diego County, except in the vicinity of Jacumba and Mountain Spring on the east slope, where IS. obscurus (q. v.) has been taken. Chipmunks 86 were very scarce in these mountains at the time of my study; however,

I observed merriami near Julian in the usual chaparral-oak habitat.

(2) Food. The cheek pouches of specimens collected in the San

Jacinto Mountains in June (Alvin Meadow, 5000', and Black Mountain,

5600') contained seeds of Arctostaphylos pringlei exclusively. Chip­ munks near Poppet Flat (4000') were observed to feed on berries of an unknown arborescent species of Arctostaphylos.

(3) Reproduction. An estrous female merriami was collected at

Alvin Meadow (5000') in the San Jacinto Mountains on 15 March 1976. The epididymis of a male taken at the same locality on 16 March contained mature sperm (Fig. 3c). Lactating females were collected in the San

Jacinto and San Bernardino Mountains between 8 June and 24 June 1975, and at Sugarloaf Mountain (8600') on 28 May 1976.

(4) Behavior. The tail-waving behavior of E. merriami was previ­ ously described (p. 77). Vocalizations include the chuck, chip, chip­ per, and trill as defined by Brand (1970), who provides sonograms of the chip and trill of this species. My conclusions regarding the respective functions of the chuck and chip differ from Brand, who believed that the chuck indicates a lower degree of alarm but is otherwise equivalent to the chip.

In merriami the chuck is given at a maximum rate of about 160 per minute, normally by a concealed individual (see also Grinnell and

Storer 1924:186). This call seems to cause other chipmunks to keep quiet and hidden. Rarely, a second concealed individual in the vicinity may begin to give the chuck also. 87

At Sugarloaf Mountain (8600') in May 1976 I attempted to call a chipmunk out of cover by squeaking. It gave one answering chip (see below) and started to emerge; immediately another individual which I had not seen before, concealed in the meadow below me, started to chuck at the maximum rate, cutting off the chip of the other animal. The chuck continued for five minutes, during which neither individual was visible.

Then the calling slowed abruptly, became irregular in rhythm, and stopped, and the chipmunk I had been stalking reappeared for an instant—taking off in the opposite direction. I have recorded several such observa­ tions for this species and also for 12. dorsalis and 12. minimus.

The chip, in contrast to the chuck, is given usually by an ex­ posed individual near its den (in IS. merriami, 12. obscurus, and 12. dor­ salis; see also the chip-quaver of 12. bulleri). In campgrounds and other public areas, chipmunks seem to become "careless" and may give the chip even when distant from their burrows. Barash (1975) similarly notes that marmots give alarm calls only near their burrow entrances.

Unlike the ventriloquial chuck, which has a relatively narrow frequency range (see Marler 1955), the chip has a wide frequency range and is easily located. Where the chuck causes other chipmunks to be quiet, the chip causes them to be noisy; it is an allelomimetic call, given in a variety of contexts. As one might predict, merriami does most of its chipping in summer, when population densities are high and lactating females remain fairly close to their nests (see Martinsen 1968 for a discussion of home range dynamics in Eutamias). The threshold stimulus level may also be partially under hormonal control (see Balph and Balph

1966). 88

The chip appears to serve a number of purposes. Its possible

role as an advertising song was discussed in Chapter 3. As an alarm

call it effectively pinpoints the location of a predator without appre­

ciable risk to the caller (which is near its burrow), and when the popu­

lation joins in chorus the predator may be disoriented. These choruses

have also been interpreted as a possible mechanism of population density

limitation (Brand 1970:121, Dunford 1970) but this has not been sub­

stantiated.

Dobroruka (1970) described two alarm calls of the African bush

squirrel Paraxerus cepapi: one described as a quiet "chook-chook", given

in long series by one inconspicuous individual and not repeated by others,

and a louder "krick" or "chip", given from a prominent rock or other ex­

posed situation and repeated by all squirrels in the vicinity. These

calls apparently correspond to the chuck and chip of Eutamias. The

author did not discuss the significance of the calls, nor did he state

the location of the burrows or nests. He did note, however, that one squirrel took refuge in a rock crevice when attacked by an eagle.

Other calls of _E. merriami include the trill and chipper. The first call is given by a number of chipmunk species (see Chapter 3) but is particularly characteristic of IS. merriami. It normally follows, or is interspersed with, a rapid series of chips, and is heard in situations of high-intensity alarm. I have also heard it given by two merriami during an agonistic encounter. The chipper, a jumbled series of notes, is given by an individual that has been startled suddenly and is racing for cover; Brand (1970) reported that all species give the chipper in this context. 89

Eutamlas merriami pricel (Allen)

Tamias pricel. Allen 1895:333.

Eutamias merriami pricel. Merrlam 1897:197.

Holotype: Adult male, skin and skull, no. 11288/9552, AMNH; from

Portola, 500' el., San Mateo Co., California; collected by J. Diefenbach on 12 April 1895; original number 511. Measurements given by Howell

(1929) are GLS 38.3; LN 13.4; ZB 20.1; LIB 8.4.

Topotype examined; MVZ 3453 (adult male, skin and skull).

Diagnosis: Sexes similar; skull of female averaging slightly larger, but only LN significant (t = 2.90, P_ < .01). Cranial depth greater, tail longer, and general coloration darker than in other sub­ species of 15. merriami; measurements given in Appendix B; see also dis­ cussion pp. 71-2. No other chipmunk species occurs within the range of pricei. North of San Francisco Bay a related species, 12. sonomae, re­ places pricei in equivalent habitat. This species is distinguished from

15. merriami by its baculum (White 1953b), vocalizations (Brand 1970:58), and coloration (Johnson 1943:125).

Distribution (Fig. 14): Collected from the south San Francisco

Bay area (Woodside, Redwood City) southward through the Santa Cruz

Mountains to the vicinity of Watsonville; also in the northern Santa

Lucia Mountains south at least to Partington Point and east to include

Santa Lucia Peak. Altitudinal range from near sea level (Santa Cruz) to at least 5000' (Chews Ridge, Santa Lucia Mountains). 90

Ecological notes; In the summer of 1974 I spent several frus­

trating weeks attempting to collect or at least to observe this sub­

species. The northern part of its range is now heavily developed and

industrialized, and chipmunks seem largely confined to the county and

state parks. I obtained permission to collect in several such areas

but returned empty-handed, a fact that does more credit to my salesman­

ship than to my training as a zoologist.

The subspecies is very common in Big Basin State Park—one of

the few areas in which I was not authorized to collect—but field obser­ vations were difficult to interpret, because the chipmunks were found

primarily near garbage cans.

Chipmunks remain also in Henry Cowell State Park, near Felton; at China Ridge in the Forest of Nisene Marks, near Aptos; at Jasper

Ridge, near Searsville Lake; in Huddart and Wunderlich Parks, near

Woodside; and in Pescadero Park. I observed pricei under natural con­ ditions only at Huddart Park, in a region of dense chaparral (Arcto- staphylos, Ceanothus, etc.), Douglas fir (Pseudotsuga douglasi), red­ wood (Sequoia sempervirens), and madrone (Arbutus menziesi). One distinct burst of chipper was heard as the animal took cover in the chaparral.

Chipmunks had not been seen at the Hastings Reservation, at the northern end of the Santa Lucia range, during that year or in recent years (J. Davis, pers. comm.). It is difficult to judge whether pricei should be considered an endangered subspecies—if, indeed, it should be considered a subspecies at all—or whether the population had recently undergone one of its periodic crashes at the time of my study. 91

Eutamias merriami kernensis Grinnell and Storer

Eutamlas merriami kernensis. Grinnell and Storer 1916:5.

Holotype: Adult male, skin and skull, no, 15022, MVZ; from Fay

Creek, 4100', 6 mi H of Weldon, Kern Co., California; collected by

H. A. Carr and J. Grinnell on 13 July 1911; original number 266. Meas­

urements given by Howell (1929:137) are GLS 38.1; LN 13.3; ZB 20.3; LIB

8.7.

Topotypes examined: MVZ 15029, 15030 (adult males); MVZ 15016,

15018, 15019, 15020, 15023, 15028, 15031, 15032 (adult females).

Diagnosis: Sexes similar; dimorphic only for MTR (t = 3.16,

P_< .01). Coloration somewhat paler than in other subspecies; meas­

urements given in Appendix B; see also discussion pp. 71-3. From

other Eutamias species, distinguished by general characters given for

IS. merriami.

Distribution (Fig. 14): Specimens designated as kernensis have

been collected in the Piute and Kiavah Mountains; in the vicinity of

Isabella Reservoir and Walker Pass, Kern and southern Tulare Cos.; and at Onion Valley and Little Onion Valley, west of Independence, Inyo Co.

This disjunct distribution has no clear topographic boundaries of which

I am aware. Johnson (1943) regarded the Onion Valley population as an independent offshoot of _E. m. merriami. Altitudinal range: 2000' 0-2 mi below Bodfish) to 8500' (Onion Valley).

I have not observed kernensis. No chipmunks were in evidence either at Onion Valley or at Walker Pass at the time of my study. 92

Eutamias obscurus (Allen)

Western Cliff Chipmunk

(Synonymy under Subspecies)

General Characters

Superficially similar to ]£. merriami, but dark dorsal and dorso­ lateral stripes normally reddish in adult summer pelage. Light stripes gray, without any yellowish tinge. Marked sex dimorphism in quanti­ tative characters of two subspecies (the third, meridlonalis, is rep­ resented by a small sample). Cranium flattened; upper incisor recurvature variable. Ossa genitalia as shown in Fig. 15. Other diag­ nostic characters vary greatly by locality and are described below under subspecies headings.

Comparisons

IS. obscurus is locally sympatric with ]2. merriami (q. v.) and with J2. speciosus (Big Bear Lake, Sugarloaf, and San Jacinto Peak). For comparison with E. merriami see General Characters and subspecies ac­ counts. E^. speciosus has a more convex cranium, more distinct pelage markings, and consistently less recurved upper incisors than 32. obscurus; the ossa genitalia are shown in Fig. 16.

12. panamintinus approaches the range of IS. obscurus to within

50 miles, in the Providence Mountains, and apparently occupies habitat equivalent to that of the adjacent _E. obscurus populations (Johnson et al. 1948). It also resembles obscurus in its reddish stripes and flat­ tened cranium (Hall and Kelson 1959:316). However, panamintinus is con­ siderably smaller than--obscurus, and its ossa genitalia are different 93

d 3

2 e

lO (? mm c f

Fig. 15. Ossa genitalia of Eutamias obscurus.

All right lateral view except f, right anteriolateral view: a, IS. o. obscurus baculum (CAS 10882). b, 12. o_. davisi baculum (UA 23276). c, IS. cu meridionalis baculum (UA 22048). d, IS. £. obscurus baubellum (MVZ 39085). e, E_. cj. davisi baubellum (holo- type; USNM 398642). f, E. o. meridionalis baubellum (UA 22623). 94

erf

Fig. 16, Ossa genitalia of Eutamias speciosus and E, panamintinus.

All 11.5x, right lateral view: a, E, s, callipeplus baculum (UA 22844). b, E. speciosus baubellum (SD 21704). c, E., j). panamintinus bac­ ulum (after White 1953b). 95

(Fig. 16). 13. bulleri resembles E.~ obscurus in bacular morphology, but the baubella of the two species differ considerably (Figs. 15, 23). IS. bulleri also has a deeper cranium, a more rounded ear, and paler color­ ation on the ventral surface of the tail.

Geographic Variation

I recognize three subspecies within E^. obscurus. Two of these,

J5. £. obscurus and JS. o^. meridionalis, have merely been changed in status, aside from minor range extensions. The approximately 100 E. obscurus examined from California north of the Anza-Borrego Desert could not satisfactorily be assigned to either of the existing subspecies, however, because of cytological and quantitative characters defined below. Also, the California populations apparently are geographically isolated from that of northern Baja California by a gap of some 60 miles

(Fig. 14). Thus a third subspecies, 15. £. davisi, was designated

(Callahan 1977). Finer splitting would produce more subspecies; the conservatism of my treatment is reflected in the separation of the group centroids as compared with those of 15. merriami (Fig. 17).

Within 15. o^. davisi, at least four populations appear mutually isolated by low desert barriers. San Gorgonio Pass and the Coachella

Valley separate the chipmunks of the San Jacinto and Santa Rosa Moun­ tains from those to the north, while the Morongo Valley separates those of the eastern San Bernardino Mountains from those of the Little San

Bernardino range. I was unable to locate the Eagle Mountain population

(the area is posted against trespassing), but Miller and Stebbins (1964:

290) state that it is isolated. 96

k m

females CO _» <0 tH o CJ W 2\

m k

males

1 i j— -2 O score 1

Fig. 17. Group centroids: Eutamias merriami and E. obscurus. m = _E. m. merriami; p = E_. m. price!; k =- E_. m. kernensis; o = E_. o_. obscurus; d = E. o. davisi. 97

Rather surprisingly, the only major morphological discontinuity

I have noted within this subspecies is between the populations of the

San Jacinto and Santa Rosa Mountains. The former have longer skulls CP

.001) and usually more recurved upper incisors than the latter. The

two populations are connected by suitable habitat, except perhaps in the

vicinity of Palm Canyon (Grinnell and Swarth 1913), but gene flow may

be reduced by intervening populations of IS. merriami. One JS. £. davisi

(MVZ 1876) from Kenworthy, midway between the San Jacinto and Santa

Rosa populations, closely resembles the latter.

Tail length differs significantly among the three subspecies of

_E. obscurus, and I have analyzed variation in this character in the same

manner described for .E. merriami (p. 75). In E_. obscurus, however, TV

is correlated neither with latitude nor with altitude (Table 7).

Subspecies

Eutamias obscurus obscurus (Allen)

Local name: mostela

Tamias obscurus. Allen 1890:70.

E(utamias). obscurus. Merriam 1897:194.

E(utamias). m(erriami). obscurus. Nelson and Goldman 1909:23.

Holotype: Female, adult, skin and skull; no. 18050, USNM, from

Sierra San Pedro Martir, near Vallecitos, Baja California del Norte,

Mexico; collected by C. H. Townsend on 1 May 1889; original number 7.

Topotypes examined: MVZ 35507, 35511, 35514, 35515, 35517, 37665

(adult males); MVZ 35501 (adult female). TABLE 7. Analysis of variance: tail length of Etitamias obscurus.

Source d.f. SS MS

Total 111 5159.9

Regression 4 518.1094 129.5274

Altitude alone 1 109.7885 109.7885 2.391

"Residual" 110 5050.1115 45.9101

Subspecies after altitude 3 408.3209 136.1070 3.137*

Subspecies alone 3 517.8 172.6 4.016**

"Residual" 108 4642.1 42.9824

Altitude after subspecies 1 .3094 .3094 .007

Residual 107 4641.7906 43.3812

r\ R due to subspecies alone = .10 (P_ < .05) s

99

Diagnosis; Female exceeds male in GLS (t = 5.53, P^ < .0001),

RL (t = 2.43, P .01), LBC (t = 4.35, P < .0001), MTR (t = 2.73, P

< .005), LN (t = 3.31, P < .005), and HB (t = 2.13, P = .01). Col­

oration as described for species, but body stripes (other than mid-

dorsal) indistinct in winter pelage. Stripes fairly clear in summer

pelage, despite Allen's (1890) description, which was based entirely

on winter specimens. Measurements given in Appendix B.

Distinguished from 12. m. merriami by ossa genitalia, pelage

coloration, shorter hind foot, and more flattened cranium. One J2. o_.

obscurus examined (Fig. 18a) had karyotype A of Sutton and Nadler

(1969), while only B has been reported for 12. merriami; however, to my

knowledge no merriami collected south of San Gorgonio Pass have yet

been karyotyped.

Distribution (Fig. 14): Collected from Mountain Spring and

Jacumba, San Diego Co., California, southward through the Sierra

Juarez and Sierra San Pedro Martir to the Rosarito Divide. This range

includes a northward extension of approximately 40 miles from that

shown in Hall and Kelson (1959:309). Altitudinal range 2300' (Moun­

tain Spring) to at least 8500' (Sierra San Pedro Martir). Note: I was

unable to find chipmunks in the Jacumba Mountains, although several

specimens have been taken there (Appendix A).

Ecological notes: Howell (1929:129) stated that obscurus is

restricted to the Transition life zone and to elevations above 7000',

but I have found it to be at least as common in pinon-juniper woodland

(4000'+) as in pine-oak forest. I have observed it only the the vicin­

ity of granite outcroppings and talus, sometimes with Arctostaphylos or K .1 •» x * A lf$ 1CW H A * *

4 li { jl ftrt Aft A A A/, ftA AO A A A A 'in

•• A A rtft Oft (1/) Aft X X ft

A A #\ a »« n b.

JU K* **

Afi Art A/) A J| A A

A A A ft n o A A

A A A • X Y * R « * >*«« •„ c.

Fig. 18. Karyotypes of Eutamias obscurus. a, female E. o. obscurus (UA 23278). b, female E. o. davisi (holotype; USNM 398642) c, male 12. o^. merldionalis (UA 22048). I !

101

Artemisia. Huey (1964) described the habitat of this subspecies as

"higher chaparral and forested areas."

These chipmunks nest in rock crevices and in burrows under

large boulders. A juvenile collected on 11 June 1975 (UA 23278) at

5000' in the Sierra Juarez was approximately 2/3 grown, suggesting that

breeding begins at least as early as March. Adults observed in the

Sierra Juarez in mid-June had already assumed the summer pelage. A

male collected at Mountain Spring, California, on 15 May 1894 was in

summer pelage (Mearns 1907).

Vocalizations include the chip, chuck, chipper, and trill. The

behavioral context of each call is essentially as described for E.

merriami (pp. 86-8). The chip is usually given from the top of a boul­

der and may continue for five minutes or more. The rate varies from

100 to 165 per minute, each accompanied by a flip of the tail.

Eutamias obscurus davisi, new subspecies

Eutamias merriami (in part). Grinnell 1908:140.

Holotype: Adult female, skin, skull, and stained baubellum; no.

398642, USNM, from Barker's Reservoir, 4000' el., 10 mi SW of Twenty-

nine Palms, San Bernardino Co., California; collected by J. R. Callahan

on 5 August 1974; original number 143. Measurements are GLS 37.5; RL

13.9; MTR 6.0; LN 11.8; ZB 20.2; CD 14.2; LIB 8.6; CB 17.5; RB 8.4; WN

2.0; HB 136.0; TV 99.0; RHF 31.0; EN 22.0; OCL 1.4.

Topotvpes examined: MVZ 74705, 74707, 74708, 74710, 74711,

74712, 74713 (adult males); MVZ 74709 (adult female). 102

Paratypes: From Black Mountain, 7000', Riverside Co., Califor­ nia: UA 23283 (adult female); UA 23291 (adult male); UA 23281 (juvenile male). From Santa Rosa Mountain, 5200', Riverside Co.: UA 23279 (sub- adult female); 7000', UA 23292 (adult female). From 3 mi N of Baldwin

Lake, 6000', San Bernardino Co.: UA 23274 (adult female), UA 23275

(adult male). From 0.3 mi N of Big Bear City, 6800', San Bernardino

Co.: SD 23264 (adult female).

Diagnosis: Female exceeds male in GLS (t = 2.57, < .01), LBC

(t = 3.03, P < .005), MTR (t = 3.49, P < .001), ZB (t = 3.55, £ < .001), and HB (t = 4.81, £ < .001). Male exceeds female in T-TN (t = 4.07, P_

< .0005). Coloration as described for species; dorsal and dorsolateral stripes persist to some degree in winter pelage but usually appear blackish when worn. Pinnae often sharply bicolored, especially in win­ ter pelage: charcoal gray or black with posterior margin light gray.

Skull larger than in other subspecies; tail length intermediate; see

Appendix B for measurements. Karyotype of four specimens examined (Fig.

18b) was B of Sutton and Nadler (1969), unlike other subspecies.

Distinguished from IS. m. merriami by general characters Cp. 92) and also by shorter tail and hind foot. In the San Jacinto Mountains, adults of the two species are separable by throat coloration: gray in

IS. o. davisi, white in IS. m. merriami. Both species are gray-throated in the San Bernardino Mountains and cannot be separated on this basis.

100% of both sexes of IS. cj. davisi and E. m. merriami were cor­ rectly classified by discriminant analysis using cranial and external measurements only (Fig. 13). 92.1% of male E. o. davisi and E. o. 103

obscurus, and 90.2% of females, were correctly classified on the same

basis (Fig. 19, Table 8). Wilks' Lambda = .31803 for male davisi and

obscurus (P = .002), .42612 for females (£ < .0001). If the observed karyological difference is consistent, presumably 100% of the two sub­

species could be separated. However, the only davisi populations yet karyotyped are those of the Santa Rosa and Little San Bernardino ranges.

Distribution (Fig. 14): Collected from the desert slope of the

San Bernardino Mountains, California, eastward through the Little San

Bernardino and Eagle Mountains; also in the San Jacinto Mountains (ex­

cluding Thomas Mountain) and Santa Rosa Mountains. Altitudinal range

2975' (Cottonwood Springs, Riverside Co.) to 9000' (San Jacinto Peak).

Ecological notes: (1) Habitat. North of San Gorgonio Pass, davisi is largely restricted to arid, rocky situations in Upper Sonoran pinon-juniper woodland below 7000'. It occurs to 8500' on the desert slope of Sugarloaf (p. 84), where it is associated with yellow pine, incense cedar (Libocedrus decurrens), and serviceberry (Amelanchier alnifolia). IS. obscurus is replaced by _E. merriami at higher elevations in the San Bernardino Mountains.

In the San Jacinto Mountains, davisi occupies the Transition life zone and is typically associated with yellow pine, sugar pine

(Pinus lambertiana), western white pine (£. monticola), several species of oak, white fir, and incense cedar. These chipmunks are usually seen among boulders, although a few were taken in clearings with rotten logs and stumps. Apparently davisi enters the Pinus contorta-Castanopsis sempervirens belt in the vicinity of Round Valley (see Appendix A), but

I was unable to collect there. 104

obscurus

davisi

•

Fig. 19. Linear discriminant scores: Eutamias obscurus davisi and E. obscurus obscurus. 105

TABLE 8. Linear discriminant coefficients: Eutamias obscurus davisi vs. E. o. obscurus.

males females

GLS .17083 -1.76296

SL .61610 2.13258

LBC 1.42878 .43603

MIR .09561 - .20950

LN - .51862 .42768

ZB .64457 -1.52877

CD .75116 - .23141

LIB - .44780 - .87477

CB - .79561 .82263

RB - .00762 .22129

WN .13632 .19029

HB - .19274 - .44585

TV .15604 - .52960

RHF - .54755 .55064 106

15. merriami is absent from the Santa Rosa Mountains, and davisi

occupies both the Upper Sonoran and Transition zones there. Again,

rocks are usually but not invariably present in the habitat.

(2) Reproduction and molt. This subspecies has a remarkably

long breeding season. Miller and Stebbins (1964:291) report females

with embryos collected on 26 January and 22 April at Quail Spring (5

mi W of type locality), and on 23 March I collected a juvenile (UA

23272) at least eight weeks old near Baldwin Lake (6000'). Since the

gestation period in chipmunks is approximately 31 days (Dunford 1974),

these populations must begin breeding in early January, at least in

favorable years. An estrous female was collected at Sugarloaf (8500')

on 28 May 1976. The davisi holotype was lactating on 5 August 1974

but had assumed the summer pelage.

At the type locality on 4 and 12 August 1974 I observed two

individuals in molt, but it was not clear whether this was a delayed

summer molt or a rather early winter molt. Miller and Stebbins (1964:

291) state that chipmunks in that region undergo the summer molt in

April or May and the winter molt in late August or early September, but

Johnson (1943:70) notes that molt seems to follow the cessation of breeding activities and that pregnant or lactating females "often re­ tain the pelage of the preceding winter well into autumn, and molt into the 'summer' pelage soon after the young have become independent."

The baculum of one of the three adult male- davisi collected in

June 1975 (SD 23262) had been broken during life, as evidenced by sym­ metrical calcification along the broken edge (Fig. 20). The missing part was not present in the preserved phallus. The summer pelage had Fig. 20. Anomalous baculum of Eutamias obscurus davisi.

See text for explanation. 12x. i i i

108

not begun to appear, although the winter pelage was nearly worn off,

and it seems likely that the injury had prevented the animal from

breeding. This was the only anomalous chipmunk baculum I have ever

found. Burt (1960:13) reported that six of 2020 mink bacula examined

(0.3%) had been broken and healed.

(3) Nests. Most of the nests and/or refuge places that I was

able to locate were as described for JE. ja. obscurus. At Baldwin Lake

and in the San Jacinto and Santa Rosa Mountains, chipmunks were seen

to enter burrows with entrances protected by large boulders. None of

these could be excavated, but I reached into one at Black Mountain

(7000') and found it to be a straight tunnel at least 36" long, with

a diameter sufficient to admit my arm to the shoulder. The angle of

descent was approximately 45°. Broadbooks (1974), Snigirevskaya (1962),

Ognev (1966), and others have described similar burrows for 12. amoenus,

IS. minimus, IS. ruficaudus, IS. townsendii, and IS. sibiricus. Broadbooks

(1974) states that these species dig the tunnels themselves; Johnson

(1943:71), however, suggests that chipmunks may sometimes utilize bur­

rows of other mammals. Confirmation of either viewpoint would require

extraordinary luck.

At the davisi type locality, in a narrow canyon, I located a

chipmunk den in a rock crevice. The vestibule was about 12" high by 18"

wide and was littered with gnawed acorn hulls. It narrowed to a natural

4" by 1-1/2" opening beyond which I was unable to investigate.

At Black Mountain (6500') I found a chipmunk burrow in a partial­

ly hollow rotten log which lay on a steep hillside. I tore the log 109 apart, and found that the burrow began in the log itself and continued into the ground. This burrow was 2-1/4" to 3" in diameter.

(4) Food and water. At the type locality, chipmunks feed largely on acorns and pinon (Pinus monophylla) seeds and on the berries of Arctostaphylos and Juniperus (see also Miller and Stebbins 1964).

A specimen taken at Santa Rosa Mountain (7000') had a piece of acorn in its mouth.

There is permanent water at the type locality, as its name im­ plies. However, most chipmunk populations in the Little San Bernardino range cannot possibly have access to permanent water, a conclusion also reached by Miller and Stebbins (1964:290).

(5) Behavior. The vocal repertoire of this subspecies is es­ sentially as described for IS. o^. obscurus. However, an estrous female davisi (field no. 221) collected at Sugarloaf (8500') on 28 May 1976 gave several chipm calls (pp. 25-26) following a series of simple chips.

Unfortunately, these calls were not recorded.

In March 1975 and 1976, both sexes of davisi seemed equally nu­ merous and vocal, but the chuck call was heard more often than the chip.

The latter was given by both sexes, but I was unable to locate and col­ lect individuals giving the chuck (see pp. 86-7), so I cannot say whether it is peculiar to one sex or the other.

All davisi collected in June and July 1975 while giving the

(simple) chip were lactating females or juveniles of either sex. The three adult males (of 27 specimens) collected in summer were silent; I could not determine whether adult males were actually scarce in that season or merely difficult to locate because of their silence. Male 110

E. dorsalis and 15. sonomae are known to become inactive or inconspic-

ouos in early summer (Dunford 1974; Hart 1967; S. Smith, pers. comm.)*

On the other hand, Balph and Balph (1966) found that male Uinta ground

squirrels (Citellus armatus) vocalized less after the breeding season,

and that females vocalized more than usual while caring for their young.

Eutamias obscurus meridionalis (Nelson and Goldman)

Peninsula Chipmunk

Local name: mostela; mostelita (dimin.)

Eutamias merriami meridionalis. Nelson and Goldman 1909:23.

Eutamias obscurus. Callahan 1975:268.

Holotype: Female, old adult, skin and skull; no. 139597, USNM, from Aguaje* de San Esteban, 1200' el., ca. 25 mi NW of San Ignacio,

Baja California del Sur, Mexico; collected by E. W. Nelson and E. A.

Goldman on 5 October 1905; original number 18268. Measurements given by Howell (1929) are GLS 35.5; IN 11.1; ZB 18.2; LIB 8.4; HB 120; RHF

33.

Diagnosis: Sex dimorphism not indicated in specimens available

(n = 8). Coloration somewhat paler than in other subspecies, but otherwise as described for species. Dorsolateral stripes indistinct or obsolescent in winter pelage, as in JE. o^. obscurus. Skull much smaller and narrower than in other subspecies, but with interorbital breadth

1. Agua.1 e = a watering place for cattle; see Fig. 21, p, H3. Ill

relatively great. Body size very small, with relatively long tail, av­

eraging 47% of total length (42% in subspecies obscurus and dayisi).

Measurements given in Appendix B. Available sample inadequate for

discriminant analysis; for univariate t-values see Table 9. Three

specimens examined cytologically had karyotype A (Fig. 18c). No other

chipmunk species occurs within the range of meridionalis.

Distribution (Figs. 14 and 21): Known only from the Sierra San

Francisco, Baja California del Sur. Altitudinal range 1000' (San

Pablo) to at least 4500' (San Gregorio). Larson (1964) stated that meridionalis does not occur on the Gulf slope, but I observed it near

Santa Marta in December 1973 (Callahan and Davis 1976).

H. W. Crosby (pers. comm.) has observed chipmunks in the Sierra

San Borja and also in the mountains south of Mulege; the latter record was confirmed independently by F. Hillary (pers. comm.). I have not had the opportunity to verify these reports. Both localities are indi­ cated by question marks in Fig. 14.

Ecological notes: (1) Habitat. At present this subspecies is known only from the Lower Sonoran life zone, although patches of oak woodland apparently occur within its range (Larson 1964; L. Arce, pers. comm.). Tables 10 and 11 list associated plant and animal species.

(2) Reproduction: Like davisi, meridionalis begins breeding quite early in the year. Ranchers in the Sierra San Francisco reported that nests containing young juvenile chipmunks were usually found in

February, and confirmed this report by presenting me with two subadults in mid-July. Both were molting into summer pelage, while two 112

TABLE 9. Student's t values: Eutamias obscurus meridlonalls vs. E_. o_. obscurus.

The sexes of merldlonalls are combined because of the small sample (App. A and B) and apparent absence of dimorphism, while those of ob­ scurus are considered separately.

males females

t P t P

GLS 5.06 .0001 7.35 .0001

EL 4.06 .001 5.33 .0001

LBC 1.27 .1 4.72 .0001

MTR 2.75 .01 5.09 .0001

LN 4.45 .0001 6.88 .0001

ZB 5.56 .0001 6.67 .0001

CD 3.85 .001 4.00 .001

LIB 0.76 .25 1.05 .25

CB 5.09 .0001 4.49 .0001

RB 3.51 .005 3.75 .001

WN 0.98 .25 0.51 .50

HB 5.68 .0001 6.14 .0001

TV 2.75 .01 1.79 .1

RHF 0.69 .50 2.55 .025 113

113 W ftfiMSiifei

\san » „ —eVpablo ®san gre^orio

10 mi

las •santa mai sane calabasas '27 30'N esteban

•san esteban \\San Ignacio

Fig. 21. Finding the Peninsula Chipmunk.

This figure is based on a composite of eight published maps, partic­ ularly those of Crosby (1974:111), Senterfitt (1972), Nelson (1922), and Meighan (1969:23), and on my own observations. The ranches at which seven of the nine extant specimens were collected—Las Calabasas and San Gregorio—do not appear on any published map known to me; their locations here are approximate. Note that there are two ranches named San Esteban. The double-dashed route is El Camino Real (not a road). The single-dashed route is that followed by the Biological Surveys Ex­ pedition of 1905. A jeep road constructed in 1973 (not shown) now con­ nects Santa Marta with Highway 1. It intersects the highway about 8 miles east of San Ignacio. 114

TABLE 10. Common plant species associated with Eutamias obscurus meridionalis.

Vernacular names, if available, are provided for convenience.

Acacia sp. Riparian only:

Bursera microphylla (Copal) Erythea armata (Blue Fan Palm)

Cercidium microphyllum (Paloverde) Ficus palmeri (Wild Fig)

Encelia farinosa (Brittlebush) Prosopis juliflora (Mesquite)

Ferocactus peninsulae (Barrel Cactus) Prunus aff. integrifolia

Fouquieria peninsularis (Ocotillo) Salix bonplandiana (Willow)

Jatropha sp.

Lemairocereus thurberi (Organpipe)

Lysiloma Candida (Palo Blanco)

Machaerocereus gummosus

Myrtilocactus cochal (Cochal)

Opuntia sp. (Cholla and Prickly Pear)

Pachycereus pringlei (Cardon)

Pithecellobium confine 115

TABLE 11. Common vertebrate species associated with Eutamias obscurus meridionalis.

Hyla regllla (Pacific Treefrog)

Dlpaosaurua dorsalis (Desert Iguana) Sceloporus magiater (Desert Spiny Lizard) Sceloporua orcuttl (Granite Spiny Lizard) Streptoaaurus mearnsi (Banded Rock Lizard) Urosaurua mlcroacutatua (Small-scaled Lizard) Cnemidophorus tlgris (Western Whiptail) Maatlcophla lateralis (Striped Racer) Crotalus ruber (Red Diamond Rattlesnake)

Buteo lamaicenals (Red-tailed Hawk) Cathartes aura (Turkey Vulture) Lophortvx californicus (California Quail) Zenaida asiatica (White-winged Dove) Phalaenootilus nuttallil (Poor-will) Calypte costae (Costa's Hummingbird) Hylocharia xantusll (Xantus' Hummingbird) Centurua uropyglalla (Gila Woodpecker) Colaptes auratus (Common Flicker) Dendrocopoa scalaris (Ladder-backed Woodpecker) Myiarchu3 cinerascens (Ash-throated Flycatcher) Savornis nigricans (Black Phoebe) Corvua corax (Common Raven) Aurlparus flaviceps (Verdin) Campvlorhynchus brunneicaoillus (Cactus Wren) Catherpes mexlcanus (Canyon Wren) Mimus polvglottos (Mockingbird) Toxostoma cinereum (Gray Thrasher) Poliootlla caerulea (Blue-gray Gnatcatcher) Phainopepla nitens (Phainopepla) Icterus cucullatus (Hooded Oriole) Amphisplza bilineata (Black-throated Sparrow) Carpodacus mexlcanus (House Finch) Pipilo fuscua (Brown Towhee) Rlchmondena cardlnalla (Cardinal) Soinua psaltria (Leaser Goldfinch)

Bassariscus astutus (Ringtail) Spllogale gracilis (Spotted Skunk) Canis latrans (Coyote) Urocyon clnereoargenteus (Gray Fox) Fells concolor (Mountain Lion) Lynx rufua (Bobcat) Ammospernophllus leucurus (Whitetail Antelope Squirrel) Citellua atricapillua (Lower California Rock Squirrel) Neotoma leplda (Desert Woodrat) Peromyscus eva (Lower California White-footed Mouse) Lepus californicus (Blacktail Jackrabbit) Svlvllagus auduboni (Desert Cottontail) Odocoileus hemlonus (Mule Deer) !I j •'

116

nonlactating adult females collected at the same time had already as­

sumed the summer pelage. The fifth specimen obtained at that time was

a juvenile, apparently born in late April or May. Larson (1964) re­

ported taking an adult male merldionalis in breeding condition, and a

nearly full-grown subadult female, in June 1963. However, Larson (in

litt.) stated that the male was a subadult when collected.

(3) Nests. This subspecies often nests in cavities in the car-

don cactus (Fig. 22). Apparently either live or fallen cactuses may

be used (J. Arce and R. Carrillo, pers. comm.), but all the nests that

I observed were in live ones, usually 10' to 15' above the ground. Two

such nests were examined closely, and each had a single opening approx­

imately 1-3/4" in diameter. Neither contained food or nesting material.

One nest was cut out of the cardon and measured more precisely: its

opening was 38 by 43 mm, and the volume of the chamber (dry) was 870

cubic centimeters.

Similar but usually larger nests are made by the Ladder-backed

Woodpecker (Dendrocopos scalaris lucasanus; Bent 1939:82), and it seems

likely that chipmunks appropriate abandoned or unfinished nests. Some

other Eutamlas species are known to use woodpecker nests in trees

(Ingles 1965, Broadbooks 1974). Caged specimens of merldionalis used

their incisors to scrape the interior of cardboard nest boxes until

the walls were paper-thin, a habit not observed in any of the six other

chipmunk species I have kept. This habit suggests that existing nests

may be enlarged and modified.

In the foothills on the Gulf side of the Sierra San Francisco,

chipmunks were observed on rock outcroppings. Observations of the 117

|JULE.1 |»v.g

Fig. 22. Peninsula Chipmunk (Eutamias obscurus meridionalis) nesting in cactus.

Drawing by Robert P. Hale, based on field sketches by the author. 118 species elsewhere suggests that meridionalis probably nests among rocks as well as in cactuses. Another saxicolous species, IS. dorsalis, often nests in hollow oaks at the southern limit of its range (Knobloch 1942,

Baker 1956:212).

(4) Food and water. JE. jo. meridionalis feeds on the flowers and fruit of most of the cacti listed in Table 10, and on the seeds of copal, paloverde, palo bianco and mesquite. According to L. Arce Cpers. comm.), the fruit of an enigmatic tree known locally as yrlai is one of the most important foods of chipmunks, but this fruit had not yet ripened at the time of my visit in July 1973. Annetta Carter has tenta­ tively identified the tree as Prunus aff. P_. integrifolia.

These chipmunks do not always live within commuting distance of water, but their diet contains a great deal of moisture. One individual was observed apparently licking dew from the surface of a cardon cactus.

(5) Behavior. The chip and trill vocalizations (pp. 87-88) were given frequently by meridionalis, both in the field and in captivity, but I did not hear the chuck or chipper. The chip was given at a rate of 30 to 50 per minute, usually by chipmunks perched on side branches of cardon cactuses 10' or more above the ground. Occasionally such an individual would enter a cavity in the same cactus after it had stopped calling, but if approached it would emerge from the cavity and descend to the ground.

E. £. obscurus (p. 101) in July 1974 gave approximately three times as many chip calls per minute as did meridionalis in July 1973.

Differences in this rate may have taxonomic significance (Brand 1970,

Dunford and Davis 1975), but the rate is also influenced by the degree 119 of alarm and perhaps by the stage of the reproductive cycle, the popu­ lation density, or other factors.

Sonograms of the chip and trill of meridionalis, prepared from recordings of my specimens, were published by Dunford and Davis (1975).

Eutamias bulleri (Allen)

Buller's Chipmunk

Local name: chichimoco"'"

Tamias asiaticus bulleri. Allen 1889:173.

Tamias bulleri. Allen 1890:92.

Eutamias bulleri. Miller and Rehn 1901:40.

Eutamias bulleri bulleri. Howell 1922:184.

Cotypes

Adult females, skins and skulls, nos, 1972/1241 and 1973/1242,

AMNH; from Sierra Valparaiso, 8700' el., Zacatecas, Mexico; collected by A. Buller on 2 August 1889.

Topotypes Examined

AMNH 1967/1236 (subadult male), 1974/1234 (subadult female).

Note: A number of others from the Sierra Valparaiso were also examined

(Appendix A), but some were represented by skulls only,, or were not identified as to sex, or were "neo-topotypes" (Doutt 1961).

1. This word is similar to an obscenity and should be pro­ nounced with care. The word mostela, which signifies a chipmunk in the mountains of Baja California, apparently is unknown on the Mexican mainland (a mustela is a weasel). 120

General Characters

A large, grayish chipmunk with distinct stripes and small, dis­

tinct postauricular patches. Median and two submedian stripes usually

black (submedian pair may be brown, median partly brown). Light stripes

gray, without cinnamon or yellow tinge; lateral pair of dark stripes

reduced, often indistinct. Tail narrow, sparsely haired, with ventral

surface light yellowish-tan medially. Pinna broad, rounded at tip, and

distinctly tricolored: charcoal gray with anterior margin rusty and pos­

terior margin whitish. Note: Allen (1889:175) made much of the tri­

colored ear, but in fact all chipmunk species included in this study

have some rusty hairs on the anterior margin of the pinna.

Male with narrower skull (t = 2.45, P_ = .01, ZB) and longer

tail (t = 3.26, I? < .005) than female; a trend toward smaller body size

in males is also indicated (t = 1.86, < .05). TV averages 43.1% of

total length in males, 39.6% in females. For measurements see App, B.

Ossa genitalia as shown in Fig. 23. Karyotype of two specimens examined (Fig. 24a) was A of Sutton and Nadler (1969).

Comparisons

From JE. canipes durangae, distinguished by the ossa genitalia

(Figs. 28c, p. 135; lc), by the absence of a cinnamon wash on the upper parts, and usually by lighter ventral tail coloration. Individuals with typical coloration are readily distinguishable in the field; however, some durangae examined (e.g., UA 9775, 9776; MSU 10274, USNM 95333) have tails like those of bulleri. All these are from northern Durango or southern Chihuahua, outside the range of bulleri. Quantitative 121

Fig. 23. Ossa genitalia of Eutamias bulleri.

Both IQx, right lateral view: left, baculum (KU 109108); right, baubellum CAMNH 1974/1234; topotype). 122

«• V» *•«-, ...

>\}) i{(\ /»r> Af 56 0i\

op on uft *«*

« *w XX #% /\ r« «• #% • • a.

(t XI *» 51 8ft M ft* A * 64

HA IMA aA

n tr A & X X

Fig. 24. Karyotypes of two Eutamias species. a, female E. bulleri (field no. 220). b, female E, canipes durangae (UA 22843). 123 differences: both sexes of bulleri with longer braincase (t = 3.51, J?

^ .0005) and shorter maxillary tooth row (t = 3.62, £ < .0005) than durangae; male bulleri with longer tail (t = 4.78, P_ < .0005) and long­ er hind foot (t = 3.49, £ < .005) than male durangae; female bulleri with more flattened braincase (t = 3.45, < .005, CD) and shorter nasals (t = 2.46, 1? = .01) than female durangae. 100% of both sexes of 12. bulleri and 12. canipes durangae were correctly classified by dis­ criminant analysis (Fig. 25, Table 12) using cranial and external meas­ urements only. Wilks' Lambda = .00012 for males, .02254 for females

(P < .0001 for both).

From 12. dorsalis, distinguished by the ossa genitalia (Fig. 7), by the round-tipped ear and more distinct stripes of bulleri, and pre­ sumably by karyotype (Fig. 9); however, no E_. dorsalis from Durango have been karyotyped. For comparison with E_. obscurus see that account.

Distribution

Collected from 2.5 miles east of Los Mimbres, Durango, south­ ward along the east base of the Sierra Madre to the canyon of the Rfo

Mezquital; also south of the Rfo Mezquital in the mountains of southern

Durango, Zacatecas, and extreme northern Jalisco (Fig. 26). This range includes a northwestward extension of approximately 80 miles Csee Hall and Kelson 1959, Baker and Greer 1962). Altitudinal range 6800' (10 mi

NE of Huejuquilla, Jalisco) to at least 8700' (type locality).

The northern limit of the range has not been determined, but strictly on the basis of topography it would appear to be the canyon of the Rfo Nazas. North of this barrier, dorsalis replaces E. bulleri 124

females

n n -8

males

-ao -40 40 score

Fig. 25. Linear discriminant scores: Eutamias bulleri (shaded) and 12. canipes durangae. 125

TABLE 12. Linear discriminant coefficients: Eutamlas bulleri vs. IS. canlpes durangae.

males females

GLS 80.57591 -21.36824

RL -88.96666 19.89502

LBC -62.43563 7.34048

MTR -74.52496 - .19006

LN 28.27614 - .73688

ZB 44.39694 .03458

CD -12.11046 .10454

LIB - 6.27878 .48629

CB -48.38567 - 1.05040

RB 50.82990 .79190

WN 45.60655 - .17168

HB - .15839

TV - .85949

RHF 3.03679 126

c h i hua hu a

durango

• «P

GULF OF ^ CALIFORNIA •c

50 100 mi

Fig. 26. Distribution of Eutamias bulleri, JS. canipes durangae, and E. dorsalis dorsalis in northwestern Mexico.

Square = bulleri, circle = durangae, triangle = dorsalis; arrow = type locality. 127

in equivalent habitat. Curiously, however, Petersen (1976) does not

include Eutamias in his discussion of mammalian biogeography in that

region. j5. canipes durangae occurs on both sides of the Rio Nazas, but within the range of 13. bulleri this species seems largely restricted to

the western slope of the Sierra Madre. Because the Rfo Nazas cuts only

the eastern slope, it is not a barrier to durangae.

Geographic Variation

No significant geographic variation is apparent within the re­ stricted range of 15. bulleri, so no subspecies are designated.

Ecological Notes

Habitat. I was unable to visit the type locality, but the alti­ tude suggests a habitat of pine-oak forest (Alfaro et al. 1972). Resi­ dents of Jimenez del Teul, Zacatecas, confirmed that chichimocos are common among the pines in the high mountains. Baker and Greer (1962) collected bulleri in pine-oak habitat in southern Durango, and Genoways and Jones (1973) reported that the species was associated with oak, man- zanita, and scattered small pines in northern Jalisco.

I observed and collected bulleri at two localities in Durango:

21 miles south of Ciudad Durango (7700') and 2.5 miles east of Los Mim- bres (7450'). At the first locality, chipmunks occupied massive col­ umnar rock outcropplngs with oak and manzanita; Pinus engelmanni grew above and at the base of the cliffs. At the second locality, chipmunks were very abundant on rocky cliffs and stone walls along the valley of the Rio Mimbres. The streambed was dry in mid-May 1976. Trees included 128

Pinus chihuahuana, P^. engelmanni, Junlperus sp., Populus tremuloides,

and an unidentified deciduous oak.

E. canipes durangae, by contrast, was observed only in denser

and more mesic woodland (Pinus durangensis, Arbutus glandulosa, etc.)

and was not associated with cliffs, although Hooper (1955) reported that

it sometimes uses rock crevices. Annual precipitation on the west slope

of the Sierra Madre in the vicinity of El Salto, where durangae appar­

ently reaches its maximum abundance (pers. obs.; specimens examined;

Baker and Greer 1962), is nearly twice that on the eastern slope

(Angeles et al. 1964).

Reproduction. All three adult male bulleri collected at Rfo

Mimbres on 17-19 May 1976 had scrotal testes, and the epididymes con­

tained very large numbers of sperm. All the sperm were immature, however

(Fig. 3). None of the three adult females taken during the same period

was pregnant, lactating, or visibly estrous. Five of the adults were

in fresh summer pelage; the sixth, a male, is questionable because of a

skin disease.

One female subadult was taken 21 miles S of Ciudad Durango on

13 May, indicating that breeding may begin at least as early as January.

The Rfo Mimbres population probably bred in late summer, judging by the

condition of the specimens taken in May. A female (KU 109106) collected

in northern Jalisco on 10 November 1966 appears to have been lactating,

although the collector did not record its reproductive condition.

If IS. bulleri in southern Durango does in fact have a bimodal reproductive cycle, as the preceding observations suggest, then it skips 129

entirely around the breeding season of adjacent _E. canlpes durangae

populations. A female duransae (UA 22843) collected 33 miles W of El

Salto on 8 May 1974 contained four small embryos when sacrificed two

weeks later. A juvenile durangae approximately 2/3 grown was observed at

the same locality on 7 May; presumably it was born in March. Baker and

Greer (1962) reported pregnant and lactating durangae between 26 June

and 20 July.

Nests. A. Buller reported that 15. bulleri at the type locality

"live in hollow trees, but come down to the ground to feed" (Allen 1889).

This statement seems reasonable but is difficult to evaluate. At the two sites where I observed these chipmunks they behaved in just the op­ posite manner, nesting underground but often climbing trees to feed.

A burrow located at the Rifo Mimbres site had its entrance pro­

tected by a large boulder at the base of the cliffs. The tunnel, which was about 3" in diameter, descended at an angle of about 30° for a foot or so and then veered off sharply to the left. A nest located at the other study area was not investigated in detail, but it too was located among boulders at the base of a cliff.

Predators and Parasites. Notwithstanding their abundance, the chipmunks at Rfo Mimbres were in dreadful condition. Two of the three live-trapped had lost most of their tails, and other virtually tailless

Individuals were observed. Chipmunks often lose the tips of their tails, which come off very easily when grasped; the vertebrae do not sever easily, but the skin slips off and the exposed vertebrae dry up later.

Either predators or conspecifics may be responsible (Preble 1936, Miller i I I

130

and Stebbins 1964:290, Michener 1976), but I have never seen such ex­

treme examples nor in such numbers as at R^o Mimbres.

All the chipmunks were heavily laden with fleas (probably

Monopsyllus polumus), and one had a heavy infestation of roundworms

and an unidentified skin condition resembling mange.

The most likely predator observed was the red-tailed hawk (Buteo

jamaicensis), which "hunted" daily along the face of the cliffs, but

was not actually seen to capture anything.

Food. Chipmunks at Rio Mimbres fed on the seeds of Juniperus

sp. and on the flowers of an unidentified deciduous oak. At the study

site 21 miles S of Ciudad Durango, a chipmunk appeared to be eating the

new growth at the tip of a Plnus engelmanni branch.

Behavior. These chipmunks frequently climbed to 15-20' when

feeding. On one occasion at least six individuals were observed feeding

on oak flowers in the same tree. When approached, they did not climb

higher but instead descended to the ground and hid among boulders.

Three different vocalizations were heard in the field. One was

the familiar chuck, given in its usual context: a concealed and distant

chipmunk would give a series of chuck calls as I approached the cliff

or after I had shot another individual.

A second vocalization may be written as tcfr-tch-tch. This was

given by a live-trapped female at Rio.Mimbres, shortly after she was

placed next to a second caged female. The sound was different from the

chip of other species; it was a short, explosive sound rather than an

articulated syllable. It was also distinct from the growl (Brand 1970)

often given by chipmunks caged together. The sound most nearly resembled li

1

131

a call given by E_. sibiricus (Fig. 2b) and described by Smit (1976) as

Fauchlaute (= "spitting sound"). This sound was given by the female

bulleri for only a few seconds and was not recorded.

The third vocalization, which will be called the chip-quaver

(Fig. 27a), is not given by any of the other 16 Eutamias species whose

vocal behavior has been studied, or by Tamias striatus (pers. obs.;

Brand 1970; Smit 1976; S. M. Russell, pers. comm.). Only two bulleri

were heard to give this call: one of the adult females collected at Rfo

Mimbres (recorded) and the subadult female collected 21 miles south of

Durango. Each was shot while calling from the top of a boulder within

6' of the entrance to a burrow that it (or another chipmunk) had prev­

iously been seen to enter. The chip-quaver begins with the syllable

"whisk", or in other words the usual chip given by other species; note

that the context is also that of the chip, except that the call is not

repeated by other individuals in the vicinity. The initial syllable is

followed by a loud series of quavering notes, similar to those sometimes

produced by the California ground squirrel (Citellus beecheyi). The

chip-quaver of the subadult descended sharply in pitch toward the end.

This call was given at a rate of only 4 to 5 per minute, at uni­

form intervals of 12 to 15 seconds. 15 calls were recorded; the number

of syllables per call ranged from 11 to 19 (X = 13.47, sg = .70). De­

spite this unusual vocalization, the hyoid apparatus of JE. bulleri does

not differ from those of other chipmunk species.

I noted previously (Callahan 1975) that the trill vocalization

is given by E_. bulleri. This statement referred to J£. canipes" durarigae, l;u icmmm

L'-Fir Mf&nr.r. f a. ' , '

•A< i ; C %$i\ ^ ill/ lltw/L ^lirUHUnHfiiWMiinwIitt'ii Win)

Fig. 27. Sonograms of Eutamias bulleri and IS. canipes durangae vocalizations, a, chip-quaver of 12. bulleri female (field no. 218). b, chipm and trills of IS. bulleri female (field no. 223): from left to right, chipm and chip followed by two- and three- syllable trills, c, trill of IS. canipes durangae female (UA 22843). 133 which at that time was 12. bulleri durangae. As it turns out, however,

_E. bulleri (s_. s_.) also gives the trill. One of the females trapped at Rfo Mimbres in May 1976 was kept alive in Tucson until October. She was silent and extremely secretive until mid-August, when she began to run around the cage in a highly agitated manner. When startled by the approach of an observer she would utter short single- or double-noted chirping sounds; some of the latter closely resembled the chipm (Fig.

27b; p. 26). The amount of activity and vocalization increased during

August, and the calls gradually became typical trills of three to nine or more syllables.

The timing of this behavior coincided with the projected breed­ ing season of the Rib Mimbres population (p. 128). The female showed no external sign of estrus, but she was not examined daily, nor were smears of the vaginal epithelium taken. Moreover, Saddington (1966) reported that a female JE. sibiricus gave no indication of estrus other than a change in vocal behavior.

None of the longest trill vocalizations of JE. bulleri were re­ corded, but shorter ones are shown in Fig. 27b. Note the continuum between the chipm and trill. A trill given by a caged female E. canipes durangae (UA 22843) is given for comparison in Fig. 27c.

Eutamias canipes (Bailey)

The numerous montane islands of the American Southwest favor superspecies formation (Mayr 1970:287), as exemplified by the Eutamias quadrivittatus group. Ttfhile this superspecies is interesting from an evolutionary viewpoint, it is a taxonomist's nightmare. 134

Figs. 28 and 29 show the ossa genitalia of most of the taxa

comprising the quadrivittatus group. Those populations previously re­

ferred to 12. bulleri durangae and to IS. b^. solivagus clearly belong

here; both geographically and morphologically they are closest to IS.

canipes. The group centroids of several IS. canipes populations and

of JE. bulleri are plotted in Fig. 30.

All nominal species in the quadrivittatus group are allopatric.

I have omitted E_. umbrinus and jS. bulleri from this group, with which

they have often been included (Howell 1929), because their ossa geni­

talia are considerably different and because they have achieved para-

patry with jS. quadrivittatus and E_. canipes respectively (Long and

Cronkite 1970, and previous account).

The definition of morphospecies in the quadrivittatus group is

not as simple a matter as suggested by Fleharty (1960), who compared

only the most divergent populations. As shown in Fig. 28, there is very

nearly a continuum in bacular morphology within the group (see also

Findley et al. 1975:103). Karyology does not help, for all forms ex­

amined have Neotamias-A (Fig. 24b; Sutton and Nadler 1969; B. Patterson,

unpublished), except jS. quadrivittatus—and JE. ruficaudus, which prob­ ably is an offshoot of the same lineage. Pelage coloration varies along the usual environmental gradients, and the skulls of all populations ex­ amined thus far are quite similar, differing only in size. A complete revision of the quadrivittatus superspecies is beyond the scope of the present study. 135

Fig. 28. Bacula of Eutamlas quadrivlttatus superspecies.

All right lateral view except a, right lateral and dorsal views, a, 12. canipes canipes (UA 2532). b, JE. canipes solivagus (KU 33104). c, E_. canipes durangae (MVZ 115343). d, unnamed subspecies of 15. canipes (see Appendix A), presently classified as E_. cinereicollis cinereus (NMS 5189). e, 12. quadrivlttatus quadrivlttatus (after White 1953b). f, IS. cinereicollis cinereicollis (after White 1953b). 136

Fig. 29. Baubella of Eutamias quadrivittatus superspecies.

All 13.5x, right lateral view: a, E.. canipes sacranentoensis (WHP 5518). b, E^. c.. solivagus (USNM 16884). c, E_. ,g_. quadrivittatus (MHP 9). d, E_. cinereicollis cinereus (WHP 6109), For E_. canities duraneae. see Fig. lc. 137

6

4

2

O C s' -2 s

-4- females

01

® AJ U O- ou to 4J

2

O -2

-4 males

-20 -16 -12 -8 -4 0 4 8 12 score 1

Fig. 30. Group centroids: Eutamias bulleri and _E. canipes. b = JE. bulleri; c = _E. _c. canipes; d = _c. durangae; s = E. _c. sacramentoensis; s' = JE. solivagus. CHAPTER 7

DISCUSSION

Morphological, cytological, Immunological, and biochemical ev­

idence indicates that the present assemblage of western chipmunk species

probably originated no earlier than the Pleistocene (Chapter 3; Hight

et al. 1975; Hight, pers. comm.; Nadler et al. 1975). This conclusion

is supported by the parapatric distribution of most species. Behavioral

differences apparently allow the coexistence of I!. speciosus and 12. senex

in California (Grinnell and Storer 1924), but such cases are the excep­

tion rather than the rule. The often-cited habitat segregation of E_.

dorsalis and 15. minimus in the Great Basin is not clearcut, and it dif­ fers from the more usual altitudinal zonation only to the extent that sagebrush and pinon-juniper woodland interdigitate (pers. obs.).

In a study of the birds of New Guinea, Diamond (1972) concluded

that altitudinal segregation often precedes other ecological sorting mechanisms. The same generalization seems applicable to western chip­ munks, except that in most instances the zone of parapatry between chipmunk species coincides (now) with a boundary between vegetation types.

Altitudinal zonation in Eutamias has received a great deal of attention (Sheppard 1965, Heller 1970, Brown 1971, Findley 1969, States

1974). The first three authors concluded that zonation results primarily from direct interference competition (R. S. Miller 1967), but Findley and

138 139

States believed habitat selection to be the deciding factor. None of

these authors mentioned certain curious phenomena; for example, the

fact that the range of altitudes and/or habitats occupied by a given

chipmunk species often varies geographically in a manner inconsistent with the usual boreal model. This and other geographic patterns will

be analyzed in the present chapter.

Origin of the Ftttamias oh scums Complex

Chipmunks (ss. JL.) appeared in western North America in the late

Oligocene or early Miocene (Black 1963; see also Chapter 4). Because

the Coast Range and Sierra Nevada had not yet risen to their present heights, the climate was "oceanic" as far east as the central Rockies

(Chaney 1940). Vegetation was fairly uniform over this area; also, plant communities were less segregated than at present (Axelrod 1958).

The Southwest was dominated by the Madro-Tertiary Geoflora, except at high elevations, where elements of the Arcto-Tertiary Geoflora were present, and at low latitudes, where the Neotropical-Tertiary Geoflora persisted (Axelrod 1958). The mountains of Baja California, including the Peninsular Ranges of California, were joined to the Mexican main­ land and were continuous with the Rocky Mountain-Sierra Madre Occidental axis (Anderson 1971).

Orogeny and a resultant trend toward drier climates during the

Miocene and early Pliocene favored expansion of the Madro-Tertiary live oak woodland; the humid tropical forests of Mexico retreated to the southeast (Axelrod 1958, Petersen 1976). Most elements of the Madro-

Tertiary flora were gradually restricted to regions with mild winters I I

140

and summer precipitation (the Sierra Madre and associated ranges),

while other elements remained in southern California and adapted to the

summer drought. Consequently, the habitat in which chipmunks probably

originated survives today only in the Sierra Madrean region.

Two members of the E_. obscurus complex—E_. obscurus and JE.

bulleri—are endemic to this region. Both have genital and vocal char­

acteristics previously defined as ancestral with respect to the sub­

genus Neotamias (Chapter 3). Sex dimorphism, a condition theoretically

favored by environmental heterogeneity (Selander 1966, Smouse 1971)

prior to the segregation of modern plant communities, is strongly

marked in both species. Moreover, each exhibits other presumed ances­

tral characters: obscurus is eurytopic, flat-skulled, and relictual in

distribution, while bulleri has a rounded ear (shared with the subgenera

Tamias and Eutamias, and with many other sciurids) and a unique, Citel-

lus-like vocalization.

In the early Pliocene the Baja California peninsula became de­

tached from the mainland and began to move toward the northwest (Ander­

son 1971). Affinities between 12. bulleri and E^. obscurus strongly

suggest that the two species are derived from a single stock whose

range was divided by the opening of the Gulf of California. Chipmunk

fossils from this period have been found in southern California (Hall

1930) but consist exclusively of teeth; about all that can be inferred

is that these chipmunks were similar in size to the larger modern

species, and occupied a chaparral-like habitat (Alf 1970). 141

At the end of the Pliocene, when the Baja California peninsula had reached essentially its present position, woodland communities were

broken up by the development of the southwestern deserts (Axelrod 1958).

The simplest explanation of existing chipmunk distribution patterns

(Fig. 14) is that the proto-obscurus populations north and south of San

Gorgonio Pass gave rise to _E. merriami and E, obscurus respectively, and that both these species crossed the Pass during a subsequent pluvial interval. By analogy, the proto-bulleri populations north and south of

the Rfo Mezquital may have given rise to E. canipes and JE. bulleri; in this instance, however, the reinvasion was not reciprocal (Fig. 26), and less detailed ecological information is available for these two species than for 15. merriami and IS. obscurus.

It appears that the fundamental niche of 12. merriami is in­ cluded within that of E. obscurus (Chapter 6) and that the more spe­ cialized merriami is also the superior competitor (see Miller 1967).

Pinon-juniper woodland is a marginal habitat for merriami (p. 84) but an optimal one for obscurus, and it is occupied by merriami only where obscurus is absent (e.g., Walker Pass). Live oak-mixed chaparral is optimal for both species, but it is occupied by obscurus only where merriami is absent (e.g., parts of northern Baja California). Arid juniper-yucca woodland and greasewood are habitats apparently accept­ able only to obscurus.

The secondary reinvasion of the San Bernardino range by obscurus probably displaced merriami from pinon-juniper woodland there. When merriami crossed San Gorgonio Pass, it eliminated obscurus from 142

virtually all Upper Sonoran chaparral-oak habitat north of the Sierra

Juarez, and it may still be expanding its range southward (Fig. 14).

The obscurus population of San Jacinto Peak is compressed into a 3000'

belt between IS. merriami and 15. speciosus, and may eventually be

squeezed out; both merriami and speciosus are relatively specialized, as

chipmunks go, with fundamental niches overlapping one another very lit­

tle but both apparently included within that of obscurus (except that

speciosus is more arboreal than obscurus). Diamond (1972) found that

the middle species of a 3- or 4-species altitudinal sequence was often

eliminated. The origin of such sequences in chipmunks will be dis­

cussed in more detail in the next section.

Zones of secondary contact between merriami and obscurus in the

San Bernardino and San Jacinto Mountains differ in certain respects. In

both localities the ossa genitalia differ sharply and altitudinal seg­

regation is maintained; but in the vicinity of Big Bear Lake and Sugar-

loaf, in the San Bernardino Mountains, other characters appear to

converge in a zone less than five miles wide. Long and Cronkite (1970)

described a similar pattern for IS. quadrivittatus and IS. umbrinus in

Colorado. In the San Jacinto Mountains, by contrast, obscurus and

merriami exhibit a moderate degree of character displacement (Brown and

Wilson 1956): the two species are readily distinguished by external char­

acters (size, coloration, tail length), and there is no zone of conver­

gence at all. An inadequate number of specimens is available from the

third major zone of secondary contact, near the California/Mexico border, but those specimens examined indicate a considerable degree of character

displacement in that region also. 143

All three zones of parapatry require further study, but a pos­ sible explanation is as follows. obscurus, being more tolerant of aridity than is IS. merriami, might well have been the first to cross

San Gorgonio Pass during a gradual shift in climate. Therefore the initial contact between the two recently diverged species would have been in the San Bernardino Mountains, and a period of introgressive hybridization, with subsequent reinforcement of isolating mechanisms, would account for the existing pattern. Then when merriami crossed to the south of San Gorgonio Pass, it would already be fully reproductively isolated from obscurus, and in the San Jacinto and Laguna Mountains hybridization would not occur.

As explained in Chapter 6, merriami has not given rise to well- marked subspecies. Character variation is essentially clinal; the only major topographic discontinuity within the species' range is San Gor­ gonio Pass, and there is a corresponding but minor discontinuity in coloration. The range of IS. obscurus, by contrast, is fragmented by desert barriers and by intervening merriami populations. The three subspecies of obscurus now constitute a dichopatric cline (Smith and

Cuellar 1972); however, gene flow has probably occurred as recently as

8,000 to 12,000 years B. P., when pinon-juniper-live oak woodland was continuous over much of the Southwest (Wells and Jorgensen 1964; Wells

1966; Wells and Berger 1967).

Altitudinal Zonation

In Chapter 6 I noted that habitat occupied by E_. merri*"ff in the

San Bernardino Mountains is occupied by JE. obscurus in the San Jacinto I

144

Mountains. Zonation is not strictly reversed, for merriami monopolizes

the Upper Sonoran oak woodland in both mountain ranges; obscurus occu­

pies the Upper Sonoran zone only on the desert slope of the San Bernar­

dino range, where this zone consists of piHon-juniper woodland. De­

spite this qualification, it appears that the ecological relationships

of the two species differ (temporarily, at least) between these two

geographic areas.

A survey of the literature reveals that geographic reversal of

zonation occurs in a number of eurytopic chipmunk species. E« minimus,

for example, occupies sagebrush, coniferous forest, and alpine situa­

tions where competing chipmunk species are absent. The presence of a

competitor excludes minimus from coniferous forest and restricts it to

one of the two marginal habitats named above CSheppard 1965). Curious­

ly, however, minimus occupies the boreal zones in the Rocky Mountain

region, where it is always (?) the uppermost species of an altitudinal

sequence; while at the western periphery of its range, in the Great

Basin and Sierra Nevada, it is confined to sagebrush and is always the

lowest in a sequence. Reversal of the Rocky Mountain zonation is also

observed at the southeast periphery of its range, in the Sacramento

Mountains of New Mexico (Conley 1970).

The best explanation appears to be that each of these fugitive

species—obscurus and minimus—occupies a higher elevational zone with­

in its center of origin than elsewhere. It is easy to visualize a res­

ident species being compressed upward by an invading competitor. E.

obscurus seems clearly to be of Sierra Madrean derivation, as previously

discussed; the region where it occurs above E. merriami is thus within i

145

its own center of origin. _E. minimus may well have originated in the

Rockies, for a large number of subspecies occur there (Hall and Kelson

1959:301); a single form (scrutator) occurs on isolated peaks and ranges

over the greater part of Oregon, Nevada, and eastern California, sug­

gesting that this region may only recently have been occupied by the

species.

A third species, E^. amoenus, appears to have originated in the

Pacific Northwest (Gambs 1965) and is largely confined to that region.

In the Olympic Mountains of Washington, amoenus is confined to alpine

and subalpine habitat above 1J. townsendii (Sheppard 1965). In central

Washington, the sequence from higher to lower elevations is amoenus-

mlnimus (Howell 1929). Still farther east, however, in southern Alberta

and western Montana, the sequence is minimus-amoenus or minimus-

ruficaudus-amoenus (Sheppard 1965, Gambs 1965, Beg 1969). Similarly,

amoenus is seen to occupy successively lower life zones as we proceed

southward from Washington. In Oregon and northern California the alti-

tudinal ranges of amoenus and E_. senex overlap broadly, but in general

the two species occupy the Transition and Canadian zones respectively

(Johnson 1943, Gambs 1965). Finally, at the southern limit of its

range, amoenus is restricted to the arid eastern slope of the Sierra

Nevada, where the sequence is alpinus-speciosus-amoenus-minimus (Grinnell

and Storer 1924, Heller 1970).

The distribution of amoenus clearly contradicts the boreal model

of Findley (1969). Certain more specialized chipmunk species, by con­

trast, fit Findley's model very well. E_. speciosus, for example, has

established populations at the summits of several isolated peaks in 146

southern California (Johnson 1943). The species probably originated in

the northern part of its present range, however, for it is restricted

to the Canadian life zone, and none of its relatives—E. sen ex, JE.

ochrogenys, IS. siskiyou, and JE. umbrinus, according to my interpreta­

tion—occur south of the Sierra Nevada.

A more ambiguous example is provided by the 12. quadrivittatus

superspecies, which probably originated in the Sierra Madrean region,

as discussed in the previous section. _E. canipes occurs above J2. mini­ mus in the Sacramento Mountains of New Mexico (Conley 1970), but far­

ther to the north and northwest, canipes and other members of the quad­ rivittatus group seem always to occur below minimus• This reversal of zonation would be predicted by either the boreal or the center-of-origin model.

In the White Mountains of Arizona, the elevational sequence of species is minimus-cinereicollis-dorsalis (Findley 1969), in Colorado minimus-quadrivittatus-dorsalis (Warren 1942), and in western Montana and southern Alberta- minimus-ruficaudus-amoenus (Beg 1969). Note that ruficaudus and the quadrivittatus superspecies have similar bacula, as do amoenus and dorsalis (White 1953b). To the extent that this char­ acter reflects relationships, these appear to be equivalent species associations. Biogeographic data may therefore provide important cor­ roborative evidence regarding species relationships. Eventually it should be possible to correlate major Pleistocene events with the ex­ pansion of each progenitor species into its present range.

My hypothesis that the altitudinal range of a resident species may be compressed upward by an invading species implies that 147 interference competition of some sort takes place. As previously mentioned, several authors have attributed existing patterns of zona- tion to direct interspecific aggression. States (1974), however, noted that interspecific encounters are very infrequent under natural condi­ tions. He concluded that interspecific aggression may have been im­ portant historically in establishing distributions, but that habitat selection appears to be the more Important factor at present. This hypothesis explains why zones of parapatry generally follow ecotones, but the aggression hypothesis can also be used to account for this phenomenon: Brown (1971) believed that the ability of one species to behave aggressively toward another may depend upon habitat structure.

While it is true that selection would probably favor the replace­ ment of overt aggression by some mechanism requiring less expenditure of energy (States 1974), divergence in habitat preference is not the only available course. A possible alternative is suggested by the scent-marking behavior of certain chipmunk species. Sheppard (1965) reported that E_. amoenus and E_. minimus often rub their cheeks against a perch or other substrate, apparently to spread the secretion of a sebaceous gland in the jaw. Dobroruka (1972) described similar behav­ ior in captive E. sibiricus but reported that marking with urine is more common in this species. Apparently all chipmunks of both sexes use the same marking points, and there is no evidence of intraspecific terri­ toriality in any species, except in the sense that an individual is generally dominant near its own den (Dunford 1970). However, the main­ tenance of parapatric species ranges by mutual or unilateral inter­ ference is essentially a form of group interspecific territoriality. 148

Because most chipmunk species are similar in appearance and normally do not vocalize during interspecific encounters, species recognition is probably olfactory, and scent marking—whatever its primary or original function-—would provide a medium for the replacement of overt aggressive interference by indirect interference (Miller 1967). APPENDIX A

SPECIMENS EXAMINED

Eutamias dorsalis dorsalis

(71, including 49 adults)

Arizona: Santa Catalina Mts,, 30 UA; Chlricahua Mts., 24 UA;

Graham Mts., 3 UA, 5 ASU; Pinal Mts., 2 UA; Rincon Mts., 1 UA.

New Mexico: Guadalupe Mts,, 2 USNM.

Chihuahua, Mexico: 2 mi W of Samachique, 7000', 1 KU.

Durango, Mexico: 13 mi S of Tepehuanes, 8100', 3 MSU.

Eutamias dorsalis sonoriensis

(24, including 20 adults)

Sonora, Mexico: 15 mi NE of Guaymas, 11 UA; vie, San Carlos Bay,

1 CSLB, 4 LACM, 6 UA, 2 uncatalogued.

Eutamias merriami merriami

(85, including 66 adults)

California, Fresno Co.: Kings River, 13 MVZ. Kern Co.: Old Fort

Tejon, 1 MVZ; Rancheria Creek, 1 MHP. Los Angeles Co.: Bushtit Camp­ ground, 1 MHP; Chilao, 1 MVZ; Crystal Lake, 1 LACM; Horse Flats

Campground, 1 LACM; Mt. Waterman, 1 LACM; Mt. Wilson, 1 MVZ; Pacoima

Canyon, 1 LACM; Pine Flats, 2 LACM, 1 MVZ; Sandbergs, 1 MVZ; Verdugo

Hills, 1 LACM. Monterey Co.: Jolon, 6 MVZ; 8-3/4 mi WNW Jolon, 1 MVZ,

149 15Q

Riverside Co.: Alvin Meadow, 2 SD, 2 uncatalogued; Black Mtn., 2 UA;

Kenworthy, 1 MVZ; Poppet Flat, 1 SD, 1 MVZ; San Jacinto Mts., 1 USNM;

Schain's Ranch, 1 MVZ; Strawberry Valley, 2 USNM; Thomas Mtn., 3 SD,

1 UA. San Bernardino Co.: E end Big Bear Lake, 1 UCLA; Bluff Lake, 1

SD; Deep Creek, 1 UCLA; 1 mi W of Fawnskin, 1 SD; Fleming's Mills, 2

AMNH; 1 mi S of Lake Arrowhead, 2 SD; Poligue Canyon, 1 SD; San Bernar­ dino Mts., N of San Bernardino, 1 AMNH; Santa Ana River, 1 MVZ; Seven

Oaks, 2 MVZ, 2 SD; Wildhorse Meadows, 2 UA. San Diego Co.: Campbell's

Ranch, 1 AMNH; Cuyatnaca Mts., 1 MVZ; Julian, 2 MVZ; Laguna Mts., 2 MVZ,

1 SD; Palomar Mtn., 1 SD, 1 UCLA; Volcan Mtn., 1 MVZ; Warner's Ranch,

1 SD; Witch Creek, 1 SD, 1 UCLA. Ventura Co.: Mt. Pinos, 1 UA; Ojai

Valley, 1 UCLA.

Eutamlas merriami kernensis

(60, including 49 adults)

California, Kern Co.: Bear Mtn., 1 MVZ; Bodfish, 2 MVZ; Fay

Creek, Weldon, 10 MVZ; French Gulch, Piute Mts., 10 MVZ; Isabella, 2

MVZ; Kelso Valley, 2 MVZ; Little Lake, 3 AMNH; Little Onion Valley, 3

MVZ; 4 mi SW of Olancha, 1 MVZ; Walker Basin, 9 MVZ; Walker Pass, 5 MVZ.

Tulare Co.: Fork of Big and Little Kern Rivers, 4 AMNH; Loyd Meadow, 2

AMNH; Morro Rock, 1 MVZ; Taylor Meadow, 5 MVZ.

Eutamlas merriami price!

(46, including 42 adults)

California, Monterey Co.: Big Pines, 6 MVZ; 1.5 mi S of Chalk

Peak, 3 MVZ; Chews Ridge, 5 MVZ; "Mountains", 1 MVZ; Palo Colorado 151

Canyon, 1 MVZ; San Antonio Creek, 2 MVZ; Santa Lucia R. S., 1 MVZ. San

Mateo Co.: Portola, 1 MVZ; Woodside, 2 CP, 1 UA. Santa Clara Co.: Black

Mtn., 1 MVZ. Santa Cruz Co.: 1 mi E of Aptos, 2 MVZ; Bonny Doon, 7

MVZ; 1/2 mi N of Brookdale, 1 MVZ; 2.5 mi N of Corralitos, 1 MVZ; Head of Doyle Gulch, 3 MVZ; 1.2 mi E of Glenwood, 1 MVZ; Granite Creek, 1

MVZ; Santa Cruz, 4 MVZ; 4 mi W of Watsonville, 2 MVZ.

Eutamias obscurus obscurus

(77, including 52 adults)

California, San Diego Co.: Jacumba, 1 USNM; Mountain Spring,

1 USNM.

Baja California del Norte, Mexico: La Grulla, 25 MVZ; Laguna

Hanson, 5 MVZ; 14 mi N of Laguna Hanson, 5 CAS, 1 UA; N end Nachoguero

Valley, 1 MVZ; Sierra San Pedro Martir, 31 CAS; Vallecitos, 7 MVZ.

Eutamias obscurus davisi

(103, including 84 adults)

California, Riverside Co.: Black Mtn., 4 SD, 10 UA, 1 uncata- logued; Dark Canyon, 2 UA; Eagle Mts., 2 MVZ; Garnet Queen Mine, 1 MVZ; vie. Fuller's Mill, 5 MVZ; Jolley Springs, 1 MVZ; Kenworthy, 1 MVZ;

Lower Covington Flat, 5 MVZ; Pinyon Wells, 3 MVZ; Round Valley, 1 MVZ;

San Jacinto Mts., 1 USNM; San Jacinto Peak Trail, 3 USNM: Santa Rosa

Mtn., 3 MVZ, 3 SD, 4 UA, 1 uncatalogued; Strawberry Valley, 4 MVZ, 12

USNM; Toro Peak, 2 MVZ. San Bernardino Co.: Baldwin Lake, 5 SD; 3 mi

N of Baldwin Lake, 4 UA; 5 mi N of Baldwin Lake, 1 UA, 1 uncatalogued;

4.5 mi ESE Baldwin Lake, 1 SD; Barker's Reservoir, 9 MVZ, 1 UA; 0.5 mi

N of Big Bear City, 1 SD; 1.5 mi NW of Big Bear City, 1 SD; Black Rock 152

Springs, 2 MVZ; Doble, 1 MVZ; Quail Springs, 4 MVZ; Sugarloaf, 1 MVZ,

1 UA; 6 mi W, 3 mi S of Twentynine Palms, 1 MVZ.

Eutamias obscurus meridionalis

(8, including 7 adults)

Baja California del Sur, Mexico: Rancho Las Calabasas, 1 CAS,

4 UA; Rancho San Gregorio, 2 UA; San Pablo, 1 USNM.

Eutamias bulleri

(77, including 27 adults)

Durango, Mexico: 21 mi S of Ciudad Durango, 1 AMNH; 24 mi SSE

of Ciudad Durango, 3 MSU; 6 mi SE of Llano Grande, 1 MSU; 2.5 mi E of

Los Mimbres, 6 AMNH; Rancho Las Margaritas, 6 MSU.

Jalisco, Mexico: 10 mi NE of Huejuquilla, 20 KU,

Zacatecas, Mexico: Sierra Madre, 9 USNM; Sierra Valparaiso, 5

AMMH, 19 USNM; 9 mi NW of Valparaiso, 7 MSU,

Eutamias canipes canipes

(95, including 43 adults)

New Mexico: Capitan Mts., 10 MSB, 42 USNM; Gallinas Mts., 2

MSB; Guadalupe Mts., 1 MSB; Jicarilla Mts., 7 USNM; White Mts., 3 MSB,

1 USNM.

Texas, Culberson Co.: Guadalupe Mts,, The Bowl, 3 MSB, 21 TCRC,

4 USNM; McKittrick Canyon, 1 TCRC. 153

Eutamias- canipes durangae

(75, including 41 adults)

Chihuahua, Mexico: 7 mi SW of El Vergel, 1 MVZ; Guadalupe y

Calvo, 12 USNM; Sierra Madre, 14 USNM.

Durango, Mexico: vie. El Salto, 7 KIT, 1 MSU, 4 MVZ, 13 USNM;

Hacienda Coyotes, 1 MSU; vie. La Ciudad, 1 KU, 1 MVZ, 1 UA; vie. Las

Adjuntas, 13 KU, 1 MVZ; 6 mi H of Sandias (35 mi SW of Hidalgo del

Parral), 2 UA; vie. San Luis, 2 MSU; 18 mi SSW Tepehuanes, 1 MSU.

Eutamias canipes sacramentoensis

(72, including 22 adults)

New Mexico, Sacramento Mountains: vie. Cloudcroft, 18 MHP, 38

MSB, 3 UA, 11 USNM; Eagle Creek, 1 UA; 2 mi W of Mayhill, 1 NMS.

Eutamias canipes solivagus

(31, including 22 adults)

Coahuila, Mexico: 12-13 mi E of San Antonio de Alazanas, 17 KU;

Sierra Guadalupe, 14 USNM.

Eutamias canipes, unnamed subspecies

(18, ages not determined)

New Mexico, Organ Mountains: 4 MCZ, 14 NMS.

The following species require taxonomic revision, so subspecies are not designated:

Eutamias quadrivittatus QL3)

Colorado, Boulder Co.: vie. Ward, 1 MHP. Conejos Co.: vie.

Platoro, 2 MHP. El Paso Co.: 1 mi W Manitou Springs, 1 MHP. Larimer 154

Co.: vie. Estes Park, 4 MHP. New Mexico, Bernalillo Co.: Sandia Crest,

1 MHP. Colfax Co.: vie. Eagle Nest, 2 MHP. Sandoval Co.: vie. Jemez

Springs, 1 MHP. Taos Co.: vie. Tres Ritos, 1 MHP.

Eutamias cinereicollis (11)

New Mexico, Catron Co.: 10 mi E of Mogollon, 6 MHP. Socorro

Co.: Bear Trap ^anyon, 5 MHP.

Eutamias ruficaudus (4)

Idaho, Latah Co.: 13 mi N, 20 mi E of Moscow, 4 MHP.

Eutamias speciosus (13)

California, San Bernardino Co.: San Bernardino Mts., 2 AMNH;

Big Bear Lake, 1 SD. Ventura Co.: Mt. Pinos, 9 UA.

Nevada: 8 mi SW of Carson City, 1 ITA.

Eutamias sibiricus (11)

Japan, Hokkaido: Kura-Daka, 2 MVZ.

Korea, Kangwon-Do: 1 MVZ. Kyonggi-Do: 5 MVZ.

Siberia: no locality, 1 MSB; Transbaikalia, 2 MVZ.

Sciurotamias davidianus (22)

China: Chihli (Hopei?) Prov., 3 AMNH; Shansi Prov., He-Shuin,

1 AMNH; Shensi Prov., Taipashiang, 5 AMNH, Fengsiangfu, 1 AMNH; Szech- wan Prov., Tsao Po, 12 AMNH. APPENDIX B

MEASUREMENTS

All statistics in this Appendix appear in the following se­ quence: mean, variance, sample size, range, and coefficient of vari­ ation; m = males, f_ = females, * = dimorphic character (t > t q^).

Eutamias dorsalis dorsalis

m 36.20 0.44 20 35.2-37.5 1.82 GLS f_ 36.57 0.55 21 35.1-37.9 2.02

m 13.60 0.13 21 13.0-14.1 2.65 KL f_ 13.54 0.21 23 12.7-14.3 3.40

m 22.62 0.25 20 21.6-23.4 2.21 LBC* f 23.02 0.37 21 22.4-23.6 1.61

m 5.80 0.05 22 5.4- 6.1 3.97 MTR f. 5.82 0.06 24 5.2- 6.2 4.12

m 11.37 0.28 21 10.5-12.4 4.65 LN _f 11.20 0.19 23 10.1-12.0 3.93

m 19.64 0.23 22 18.7-20.8 2.45 ZB f_ 19.91 0.18 25 19.3-20.7 2.11

m 14.48 0.09 21 13.9-15.0 2.07 CD f_ 14.66 0.12 22 14.0-15.3 2.39

m 8.75 0.17 22 7.7- 9.4 4.69 LIB f_ 8.73 0.18 23 7.7- 9.7 4.81

155 156

m 17.51 0.10 22 17.0-18.4 1.77 CB f 17.57 0.08 25 17.1-18.3 1.59

m 8.70 0.29 22 7.6- 9.6 6.21 RB f 8.84 0.37 24 7.8- 9.9 6.90

m 2.55 0.06 22 2.0- 3.0 9.41 WN f 2.43 0.11 25 1.3- 2.8 13.58

m 129.76 66.89 21 105-159 8.83 HB f_ 129.94 96.53 18 110-149 7.56

m 93.76 66.89 21 76-110 8.72 TV f_ 94.72 78.92 18 72-106 9.38

m 32.48 2.06 21 29-34 4.40 RHF f 32.04 5.19 22 28-37 7.12

BT 1.16 0.01 9 1.0- 1.3 7.76

BS 3.46 0.04 10 3.1- 3.7 5.49

OCL 1.65 0.02 13 1.4- 1.9 8.48

Eutamias dorsalis sonorlensis

m 34.84 0.59 8 33.7-35.7 1.69 GLS f_ 35.04 0.59 8 33.5-35.8 2.20

m 12.70 0.10 8 12.2-13.1 ~ 2.44 RL f. 12.65 0.18 8 12.0-13.0 3.32

m 22.14 0.32 8 21.5-22.9 2.58 LBC f 22.39 0.17 8 21.5-22.8 1.83

m 5.56 0.06 11 5.2- 5.9 4.32 MTR f_ 5.42 0.12 8 5.2- 5.9 6.46 157

m 10.86 0.23 8 10.1-11.6 4.42 LN f 11.02 0.29 8 10.2-11.7 4.90

m 18.75 0.18 10 18.0-19.5 2.24 ZB f_ 18.72 0.11 8 18.3-19.2 1.76

m 13.80 0.08 11 13.4-14.4 2.03 CD f 13.89 0.10 8 13.5-14.4 2.30

m 7.85 0.12 11 7.4- 8.4 4.46 LIB f 7.82 0.25 8 7.2- 8.7 6.39

m 16.49 0.06 10 15.9-16.8 1.46 CB £ 16.60 0.03 8 16.3-16.8 1.02

m 8.56 0.38 10 7.4- 9.7 7.24 RB £ 8.76 0.04 8 8.4- 9.2 2.28

m 2.34 0.09 11 2.0- 3.0 12.82 WN f 2.44 0.13 8 1.9- 2.9 14.75

m 120.40 11.38 10 117-126 2.80 HB f_ 123.33 58.00 9 111-135 6.18

m 98.11 29.36 9 91-110 5.52 TV f_ 97.62 67.70 8 84-106 8.43

m 32.70 2.46 10 29-35 4.80 RHF f 33.11 0.86 9 31-34 2.81

BT 1.19 0.003 8 1.1- 1.3 4.20

BS 4.04 0.03 8 3.7- 4.2 4.21

OCL 1.96 0.02 5 1.8- 2.1 7.14 158

Eutamlas merriami merriami

m 38.04 0.80 22 36.3-40.1 2.35 GLS f. 38.24 0.84 38 36.7-40.7 2.40

m 13.99 0.30 23 12.6-15.3 3.90 KL f 14.10 0.29 41 13.0-15.2 3.84

m 24.05 0.23 22 23.2-25.0 2.01 LBC f 24.21 0.42 38 22.8-25.8 2.68

m 5.92 0.05 23 5.5- 6.5 3.90 MTR f. 5.93 0.05 41 5.5- 6.4 3.63

m 12.08 0.34 23 11.2-13.7 4.84 LN* f 12.56 0.37 40 11.4-13.6 4.85

m 20.36 0.31 23 19.4-21.5 2.75 ZB f. 20.30 0.21 41 19.4-21.4 2.27

m 14.72 0.13 21 14.0-15.4 2.40 CD f_ 14.72 0.08 38 14.0-15.3 1.98

m 8.71 0.20 23 7.7- 9.5 5.14 LIB f. 8.55 0.11 41 7.9- 9.4 3.81

m 17.64 0.18 22 16.8-18.4 2.40 CB f_ 17.66 0.16 37 16.7-18.4 2.29

m 8.44 0.26 23 7.5- 9.4 6.03 RB f_ 8.54 0.26 42 7.1- 9.6 6.02

m 2.59 0.12 22 1.9- 3.1 13.51 WN 2.42 0.12 41 1.8- 3.2 14.24

m 133.38 51.95 21 120-154 5.40 HB f 135.68 32.72 41 123-147 4.22 I

m 109.38 47.25 21 93-122 6.28 TV f_ 109.52 91.02 40 85-124 8.71

m 35.24 2.32 23 31- 38 4.32

RHF* O o C f 36.38 1.88 41 i 3.77

Eutamlas merrlaml price!

m 38.12 0.46 17 37.1-39.2 1.77 GLS f_ 38.72 0.84 20 36.8-40.7 2.37

m 13.90 0.21 18 12.9-14.7 3.27 RL f_ 14.16 0.13 22 13.4-15.0 2.59

£L 24.15 0,21 17 23.0-24.9 1.89 LBC _f 24.57 0,36 20 23.1-25.8 2.44

m 5.78 0.02 19 5,6- 6.2 2.66 MTR f_ 5.90 0.04 22 5.4- 6.2 3,61

m 12.28 0,42 18 11.1-13,4 5.30 LN* _f 12.83 0.32 22 11,8-13.9 4.39

m 20.30 0.22 17 19.4-21.2 2.31 ZB £ 20.41 0.18 22 19.7-21.1 2.05

m 15.24 0,08 17 14.5-15.7 1.83 CD _f 15.06 0.16 21 14.4-15.8 2.63

m 8.72 0.11 18 8.3- 9.5 3.81 LIB 8.70 0.14 22 8.2- 9.4 4,31

m 17.86 0.19 18 16.8-18.6 2.44 CB _f 17.88 0.19 21 17.9-18.6 2.43

m 8.72 0.13 19 8.3- 9.6 4.10 RB f 8.84 0.14 22 7.8- 9.6 4.23 160

m 2.35 0.11 18 1.8- 2.9 14.17 WN _f 2.32 0.19 23 1.5- 3.0 18.82

m 135.35 101.12 17 122-163 7.43 HB f_ 138.26 44.04 21 129-151 4.80

m 115.80 126.46 15 84-129 9.71 TV £ 116.32 53.08 22 103-130 6.26 m 36.56 2.25 17 34- 40 4.10 RHF f 36.86 2.22 22 34- 40 4.04

Eutamias merriami kernensis

m 37.44 0.60 24 35.9-38.8 2.06 GLS 37.77 0.89 18 35.9-39.3 2.49

m 13.79 0.17 • 24 12.9-14.5 3.00 RL f_ 13.92 0.28 19 13.0-14.9 3.81

m 23.65 0.33 24 22.7-25.0 2.42 LBC f_ 23.82 0.33 18 22.9-24.7 2.43

m 5.76 0.05 25 5.2- 6.1 3.72 MTR* f_ 5.94 0.04 20 5.6- 6.4 3.30

m 12.02 0.44 24 10.5-13.4 5.52 LN f_ 12.31 0.51 18 11.3-14.1 5.78

m 20.00 0.19 26 19.3-20.8 2.20 ZB jf 20.30 0.19 20 19,8-21.5 2.16

m 14.89 0.09 26 14.2-15.4 2.01 CD f_ 14.93 0.07 20 14.4-15.5 1.81

m 8.59 0.24 26 7.8- 9.8 5.68 LIB f_ 8.71 0.26 20 7.7- 9.5 5.84 161

m 17.52 0.13 26 16.8-18.1 2.10 CB f_ 17.49 0.20 21 16.7-18.3 2.58

m 8.66 0.12 26 7.9- 9.5 3.97 RB £_ 8.67 0.35 21 7.6- 9.8 6.85

m 2.61 0.08 26 2.1- 3.2 10.91 m f 2.55 0.13 20 1.9- 3.3 14.16

m 131.42 47.45 26 114-144 5.24 HB f. 132.48 38.06 21 120-145 4.66

m 108.65 43.52 26 89-125 6.07 TV _f 110.25 50.51 20 93-120 6.45

m 35.50 3.83 25 28- 38 5.52 RHF £ 35.26 4.12 21 28- 38 5.75

Eutamias obscurus obscurus

m 36.18 0.36 21 34.8-37.7 1.67 GLS* £ 36.98 0.49 25 35.8-38.1 1.90

m 13.52 0.15 21 12.8-14.2 2.90 RL* f_ 13.81 0.19 27 13.0-14.8 3.13

m 22.66 0.20 21 22,0-23.9 1.97 LBC* £ 23.20 0.15 25 22.5-23.8 1.69

m 5.74 0.04 21 5.4- 6.1 3.50 MTR* _f 5.90 0.03 28 5.5- 6.2 3.12

m 11.49 0.23 21 10.8-12.6 4.16 LN* f_ 11.95 0.23 26 10.9-12.9 4.00

m 19.64 0.25 23 18.8-20.9 2.53 ZB 19.85 0.25 26 18.4-20.9 2.53 162

m 13.70 0.06 23 13.4-14.4 1.86 CD f 13.72 0.07 26 13.3-14.2 1.95

m 8.42 0.17 23 7.6- 9.2 4.92 LIB f. 8.37 0.17 27 7.7- 9.4 4.90

m 17.50 0.14 22 17.1-18.6 2.10 CB f 17.52 0.21 26 16.8-18.5 2.62

m 8.25 0.24 23 7.2- 9.4 5.97 RB f. 8.25 0.21 28 7.3- 9.1 5.57

m 2.17 0.09 23 1.6- 2.7 13.73 WN f_ 2.23 0.12 27 1.3- 2.9 15.87

m 127.78 24.72 23 115-140 3.89 HB* f_ 130.82 38.82 28 114-140 4.76

m 91.90 13.15 20 85- 98 3.95 TV f_ 94.69 47.342 26 75-105 7.27

m 33.48 2.10 23 30- 36 4.33 RHF f. 34.18 1.06 28 32-36.5 3.01

Eutamlas obscurus davisi

m 37.29 0.30 26 36.3-38.5 1.47 GLS* _f 37.66 0.46 46 36.1-39.6 1.81

m 13.94 0.15 26 13.2-14.6 2.80 EL £ 14.02 0.18 49 13.3-15.2 3.00

m 23.35 0.17 26 22.8-24.2 1.76 LBC* _f 23.66 0.17 46 22.5-24.5 1.76

m 5.72 0.05 26 5.4- 6.2 3.74 MTR* 5.89 0.03 49 5.4- 6.2 3.07 163

m 12.04 0.28 26 11.2-13.2 4,38 LN £ 12.00 0.31 49 10.9-13.1 4.62

m 19.96 0.20 27 19.3-21.1 2.26 ZB* f 20.36 0.26 47 19.5-22.0 2.49

m 13.97 0.07 26 13.6-14.5 1.90 CD £ 14.02 0.12 47 13.4-14,8 2.42

m 8.48 0.13 28 7.8- 9.1 4.22 LIB _£ 8.63 0.11 50 7.9- 9.2 3.86

m 17.57 0.13 27 16.7-18.2 2.08 CB £ 17.73 0.12 46 16.7-18,5 1.96

m 8.40 0.16 28 7.2- 9.1 4.84 KB f_ 8.44 0.20 49 7.5- 9.7 5.29

m 2.51 0.13 28 1.8- 3.4 14.28 WN* f 2.17 0.11 49 1.7- 2.9 15.21

m 127.79 46.03 29 108-141 5.31 HB* f_ 134.73 23.61 48 120-146 3.61

m 96.23 28.81 30 84-104 5.58 TV _f 98.94 27.54 47 87-108 5.30

m 34.05 1.77 31 31- 36 3.91 RHF _f 34.45 2.04 47 31- 37 4.14

Eutamlas obscurus raeridionalis Csexes combined)

GLS 34.71 0.86 8 33.3-35.9 2.68

RL 12.73 0.27 6 12.1-13.4 4.08

LBC 22.32 0.89 6 21.5-23.9 4.26

MTR 5.48 0.01 5 5.4- 5.6 1.64 164

LN 10.64 0.17 8 10.0-11.2 3.85

ZB 18.50 0.27 8 17.9-19.2 2.81

CD 13.26 0.09 7 12.7-13.6 2.26

LIB 8.56 0.31 8 7.6- 9.6 6.54

CB 16.58 0.21 6 16.2-17.3 2.71

RB 7.57 0.07 7 7.3- 8.1 3.57

WN 2.31 0.19 7 1.7- 2.9 19.05

HB 114.00 57.33 7 106-122 6.64

TV 102.40 272.30 5 81-120 16.11

RHF 33.07 1.04 7 31- 34 3.08

Eutamias bulleri

m 37.97 0.22 11 37.2-38.6 1.22 GLS f. 38.25 0.44 14 37.0-39.5 1.74

m 14.35 0.22 10 13.9-14.8 1.62 RL 14.38 0.09 15 14.0-14.9 2.12

m 23.65 0.17 10 22.9-24.3 1.76 LBC f_ 23.89 0.20 14 23.0-24.6 1.86

m 5.98 0.04 12 5.7- 6.4 3.41 MTR f_ 6.06 0.08 14 5.7- 6.7 4.60

m 11.68 0.28 12 10.2-12.3 4.53 LN _£ 11.61 0.35 15 10.5-12.4 5.08

2L 20.16 0.23 11 19.4-20.8 2.39 ZB* f 20.57 0.14 14 20.1-21-5 1.79

m 14.98 0.14 10 14.3-15.5 2.46 CD f 14.84 0.06 13 14.5-15.3 1.66 165

m 8.57 0.22 11 7.9- 9.5 5.47 LIB f 8.63 0.08 15 8.3- 9.2 3.32

m 17.71 0.16 11 17.3-18.4 2.29 CB f 17.70 0.13 14 17.3-18.5 2.03

m 9.25 0.17 12 8.5- 9.8 4.43 RB £_ 9.31 0.36 14 8.3-10.7 6.39

m 2.97 0.12 12 2.5- 3.8 11.80 WN f 2.77 0.05 15 2.5- 3.3 8.28

m 134.54 72.47 11 119-147 6.33 HB f 140.10 23.66 10 127-144 3.47

m 102.00 26.44 10 94-112 5.04 TV* _f 91.78 68.94 9 77-108 9.05

m 36.46 0.87 11 34- 37 2.56 BHF _f 36.05 5.53 10 30- 38 6.52

Eutamias canlpes canlpes

m 36.42 0.40 19 35.3-37.5 1.73 GLS f. 36.30 0.36 15 35.2-37.2 1.65

m 13.54 0.17 26 12.8-14.4 3.04 RL t 13.44 0.10 16 12.8-14.0 2.29

m 22.78 0.12 19 22.1-23.4 1.51 LBC f_ 22.79 0.17 15 22.2-23.7 1.80

m 5.77 0.04 26 5.4- 6.1 3.35 MTR f 5.80 0.04 15 5.5- 6.1 3.45

m 11.42 0.20 26 10.6-12.3 3.89 LN f_ 11.53 0.22 16 10.9-12.7 4.05 m 19.45 0.25 24 18.5-20.5 2.57 ZB _f 19.58 0.17 16 18.6-20.3 2.12

m 14.42 0.09 20 13.7-14.8 2.08 CD f_ 14.31 0.09 15 13.7-14.8 2.06

m 8.15 0.16 25 7.5- 8.8 4.92 LIB f. 8.01 0.15 16 7.5- 8.7 4.80

m 16.97 0.11 20 16.3-17.7 1.98 CB f 16.82 0.12 16 16.2-17.4 2.05

m 8.24 0.10 26 7.8- 9.1 3.82 RB £ 8.30 0.13 16 7.6- 8.8 4.29 m 3.02 0.22 26 2.1- 3.8 15.98 WN f_ 2.73 0.26 16 1.9- 3.5 18.53

m 127.41 29.49 22 114-138 4.26 HB f_ 130.29 44.97 17 115-138 5.15

m 97.41 64.63 17 81-110 8.25 TV _f 100.94 61.00 16 90-116 7.74

m 33.70 1.29 23 32- 37 3.37 RHF f_ 33.26 4.39 17 30- 36 4.39

Eutamlas canlpes durangae

m 37.38 0.76 14 36.0-38.9 2.34 GLS* £ 38.01 0.35 22 36.9-39.5 1.55 m 14.24 0.18 17 13.6-15.1 3.00 RL f 14.43 0.25 23 13.5-15.8 3.47

m 23.17 0.37 14 22.0-24.2 2.62 LBC f_ 23.53 0.07 21 23.1-24.0 1.14 167

m 6.16 0.04 18 5.8- 6.4 3.35 MTR* f_ 6.30 0.02 22 6.0- 6.6 2.44

m 11.65 0.40 17 10.2-12.6 5.43 LN* f_ 12.10 0.25 24 11.2-13.3 4.12

m 20.22 0.11 16 19.9-21.2 1.65 ZB* £ 20.58 0.20 22 19.5-21.3 2.15

m 15.21 0.10 14 14.8-16.0 2.08 CD f 15.17 0.06 21 14.7-15.7 1.68

m 8.53 0.18 18 7.5- 9.3 5.02 LIB f_ 8.37 0.10 24 7.9- 9.1 3.79

m 17.67 0.12 13 17.0-18.2 1.98 CB f 17.73 0.11 22 17.2-18.5 1.90

E 9.20 0.18 18 8.3- 9.9 4.60 RB £_ 9.25 0.25 23 8.4-10.3 5.38

m 2.93 0.10 18 2.5- 3.6 10.77 WN f 2.88 0.10 23 2.4- 3.4 10.89

m 137.12 66.36 17 125-156 5.94 HB £_ 138.00 33.52 22 131-150 4.20

m 91.00 34.33 13 80-100 6.44 TV* f. 98.05 35.63 20 87-110 6.09

m 34.88 2.11 17 31- 37 4.17 RHF* £ 36.40 1.29 21 34- 38 3.12 168

Eutamias canipes sacramentoensis^

m 36.15 0.04 2 36.0-36.3 0.59 GLS* f_ 37.42 0.51 17 35.9-39.0 1.91

m 13.43 0.02 3 13.3-13.6 1.14 RL* f. 14.08 0.14 17 13.4-15.0 2.66

m 22.65 0.005 2 22.6-22.7 0.31 LBC* f 23.35 0.18 17 22.5-24.0 1.80

m 5.58 0.03 4 5.4- 5.8 3.07 MIR f 5.71 0.03 16 5.4- 6.0 2.89

m 11.27 0.02 3 11.1-11.4 1.36 LN* i 12.18 0.15 17 11.4-12.8 3.20

m 20.05 0.08 4 19.7-20.4 1.44 ZB f_ 20.08 0.12 17 19.3-20.8 1.74

m 14.67 0.04 3 14.5-14.9 1.42 CD f 14.52 0.04 16 14.1-14.8 1.38

m 8.28 0.19 4 7.9- 8.9 5.26 LIB f_ 8.12 0.08 17 7.7- 8.6 3.41

m 17.10 0.07 3 16.8-17.3 1.55 CB f_ 17.21 0.08 17 16.9-17.7 1.64

m 8.82 0.08 4 8.5- 9.1 3.12 RB f_ 9.04 0.11 17 8.4- 9.5 3.61

m 3.28 0.13 4 2.8- 3.6 10.96 WN f 3.25 0.06 17 2.8- 3.6 7.78

1. I was able to locate only four adult males of this sub­ species (72 specimens examined). All five sexually dimorphic charac­ ters are nevertheless significant at the .0001 level; see p. 34. 169

m 132.00 2.00 4 131-134 1.07 HB* f_ 140.62 46.78 16 130-157 4.86

m 100.50 12.50 2 98-103 3.52 TV f_ 101.80 22.60 15 95-108 4.67

m 34.00 2.67 4 32- 36 4.80 RHF f 34.43 0.57 14 33- 36 2.20

Eutamias canipes solivagus

ja 36.37 0.72 7 35.7-38.2 2.33 GLS _f 36.30 0.34 12 35.4-37.2 1.60

m 13.21 0.12 9 12.7-13.9 2.58 KL f_ 13.24 0.10 11 12.8-13.8 2.37

m 23.17 0.30 7 22.7-24.3 2.35 LBC f_ 23.07 0.21 10 22.3-23.6 1.98

m 5.69 0.04 10 5.3- 6.0 3.46 MTR f_ 5.76 0.06 12 5.4- 6.3 4.34

m 11.20 0.29 9 10.0-11.9 4.81 LN f_ 11.22 0.21 13 10.3-12.1 4.07

m 19.41 0.17 9 18.7-20.1 2.10 ZB _£ 19.62 0.13 11 19.2-20.5 1.82

m 14.64 0.03 9 14.3-14.8 1.14 CD I 14.46 0.08 11 14.0-14.9 1.96 m 8.04 0.06 9 7.7- 8.3 3.06 LIB _£ 8.05 0.09 13 7.7- 8.6 3.64

m 17.22 0.11 9 16.7-17.8 1.90 CB f 17.21 0.08 11 16.8-17.6 1.65 170

m 8.30 0.17 10 7.6- 9.1 4.95 RB f. 8.32 0.18 12 7.8- 9.1 5.04

m 2.81 0.08 9 2.4- 3.2 9.82 m f 2.72 0.09 12 2.1- 3.2 11.08

m 129.40 22.04 10 121-137 3.63 HB f 128.92 60.99 12 119-144 6.06

m 96.00 56.89 10 85-112 7.86 TV f. 102.58 77.17 12 86-112 8.56

m 33.75 2.85 10 30-35.5 5.00 RHF 1 34.42 1.90 12 31-36 4.01 LITERATURE CITED

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