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Occasional Papers

Tulane University

Museum of Natural History

3RA.X

Distributional Checklist of the Mammals along the Colorado River in the Grand Canyon

Clyde Jones

Glenn H. Clemmer

Royal D. Suttkus

Richard D. Curnow

Occasional Papers is published by Tulane University, Museum of Natural History. The Occasional Papers is dedicated primarily to Natural History: Systematics. Envi- ronmental Biology and Biogeography. The Occasi(.)nal Pai3ers will appear irregularly in consecutively numbered issues. For information and policy on exchanges, write to:

Royal D. Suttkus, Director Museum of Natural HistoiT Tulane University Belle Chasse, Louisiana 70037

When citing this publication, authors are requested to use the following: Occas. Pap. Tulane U. Mus. Nat. Hist.

Cover photo: Cardenas Creek, river mile 71, left bank, looking up river.

by Jeanne Suttkus

Printed by Drake Printers, Tuscaloosa, Alabama.

Distributional Checklist of the Mammals along the Colorado River

in the Grand Canyon

Clyde Jones

Glenn H. Clemmer

Royal D. Suttkus

Richard D. Curnow

ABSTRACT

Information obtained during field work carried out from September 1970 to June 1982 is pre- sented for 35 species of mammals that were encountered along the Colorado River in the Grand Canyon. Systematic accounts, with information on distribution, are provided for each form. Comments are made about recent changes in the habitats for mammals in the area, and some of these changes are correlated with the distribution and abundance of mammals.

Editorial Committee for This Paper

Dr. E. Lendell Cockrum Department of Zoology University of Arizona Tucson, Arizona 85721

Dr. William A. Dryer U. S. Fish and Wildlife Service Aylesworth Hall, Room 259 Colorado State University Fort Collins, Colorado 80521

Dr. Donald F. Hoffmeister Museum of Natural History University of Illinois Urbana, Illinois 61801

Distributional Checklist of Mammals along the Colorado River in the Grand Canyon

Clyde Jones

The Museum, Texas Tech University Lubbock, Texas 79409

Glenn H. Clemmer

Denver Wildlife Research Center

U. S. Fish and Wildlife Service

1300 Blue Spruce Drive Fort Collins, Colorado 80524

Royal D. SuTTKUs

Museum of Natural History

Tulane University

Belle Chasse, Louisiana 70037

Richard D. Curnow

Denver Wildlife Research Center

U. S. Fish and Wildlife Service

Denver Federal Center

Denver, Colorado 80225

Introduction

The Colorado River throughout its course from the central Rocky Mountains to the Sea of Cortez has been of considerable in- terest for many years to students of mammalian distribution. However, because of the extremely rugged terrain and the difficul- ty of access in many areas, systematic efforts to learn about the distributions of mammals along portions of the Colorado River, especially in the depths of the Grand Canyon, have lagged behind these kinds of biological investigations in other areas of the western United States.

Near the end of the last century, Merriam (1890) pioneered the survey of mammals along the Colorado River. Grinnell (1914a, 1914b) discussed the distribution of mammals in the lower Colora- do River valley of Arizona and California. Bailey (1935) presented a review of the mammals in the region of the Grand Canyon. Goldman (1937) described some of the effects of the Colorado River in northern Arizona on the distribution of mammals. Kelson (1951) and Durrant (1952) commented on the influence of the Colo- rado River on the distribution of mammals in Utah. Hayward et al. (1958) discussed the ecologic distribution of some vertebrates in the upper Colorado River basin, and Tanner (1965) studied some rodents in the vicinity of Canyonlands National Park. Mammals along the Colorado River and Green River in Canyonlands Na- tional Park were reported on by Armstrong (1979a, 1979b) and Johnson (1981). Durrant and Dean (1959) studied mammals at river level in Glen Canyon at the north end of the Grand Canyon. General information on mammalian distribution in this area and

the rest of Arizona was provided by Cockrum (1960, 1964). Hoff- meister (1971) published a comprehensive review of the mammals in the Grand Canyon National Park. Mammals of the Arizona Strip, that area of Arizona west and north of the Colorado River, were described by Hoffmeister and Durham (1971). Recent infor- mation on the distribution of mammals along the Colorado River in the Grand Canyon was provided by Ruffner and Carothers (1975), Ruffner and Tomko (1976), Ruffner et al. (1978), and Sut- tkus et al. (1978). A bibliography of works on the Grand Canyon and lower Colorado River from 1540 to 1980 was assembled by Spamer et al. (1981). Information on mammals of the national parks was presented by Van Gelder (1982).

The purposes of this report are to present a systematic account of the mammals that occur along the Colorado River in the Grand Canyon, and to provide some detailed information on the distribu- tion of mammals in this relatively unstudied area.

Methods

The specimens of mammals reported herein were obtained dur- ing more than a decade (from September 1970 to June 1982) of pe- riodic trips down the Colorado River using rubber rafts as the platforms to provide logistic support for field research on mam- mals. These specimens were assembled in order to document geo- graphic and ecologic distributions of mammals along 294.5 miles of the Colorado River from Lee's Ferry, Coconino County,

Arizona, to Sand Point. Mohave County. Arizona.

Mammals were collected by hand, snap traps, live traps, mist nets, and guns. Specimens were prepared in the field as conven- tional study skins and skulls, some partial skeletons and embryos were retained, and some specimens were preserved entire in fluid. Localities were described in the field with the aid of the Belknap (1981) series of Grand Canyon River Guides. Additional mapping was done from the "Geologic Map of the Grand Canyon National Park, Arizona" (1:62,500, Grand Canyon Natural History Associa- tion and Museum of Northern Arizona. Flagstaff. 1976). Distances down the river were taken from Lee's Ferry, river mile 0, right bank. Specimens, field notes, catalogues, photographs, and related information were deposited at the Museum of Natural History, Tulane University; the United States National Museum of Natural History: and the U. S. Fish and Wildlife Service Biological Survey collections under the care of the Denver Wildlife Research Center.

In the accounts of species that follow, synonymies were not in- cluded because this information was made available by Hall (1981). Keys to the mammals of the area were presented by Cockrum (1960), Hoffmeister (1971). and Hall (1981), and were not reproduced in this report. Vernacular nomenclature and the order of presentation were taken mostly from .Jones rt al. (1982).

Study Area

The study area includes both banks of the Colorado River from Lee's Ferry near the Arizona-Utah border to Sand Point near the Arizona-Nevada state line. This area is in one of the longest and most unobstructed portions of the Colorado River of which to con- duct a study of mammals. The area extends from just below the Glen Canyon Dam for 294.5 miles to the upper part of the Mead Reservoir.

All of the study area falls within the Arizona climatic patten, which is a regime of winter precipitation, spring drought, summer rains, and fall dry periods (Lowe. 1964). The northern part of the area studied is in the Navahonian biotic province: the southern portion is included in the Mohavian biotic province (Dice. 1943. Lowe. 1964).

Before the closure of the Glen Canyon Dam in 1963, the Colorado River was heavily laden with silt, warm in summer, and cold in winter. The water levels ranged from essentially no flow during periods of drought to flows of catastrophic proportions during some flood periods (Fenneman. 1931). Because most of the water in the river comes from the bottom of Lake Powell as released through the Glen Canyon Dam, the Colorado River is now clear and cold. The water levels fluctuate daily dependent on releases through the dam in accordance with the demands for hydroelec- tric power.

The aforementioned changes in the river have had some dramatic impacts on the vegetation along the banks throughout the study area. The riparian vegetation along the Colorado River in the bottom of the Grand Canyon has been discussed and de- scribed in detail by Lowe (1964). Hoffmeister (1971). McDougall (1964). Dolan ft al (1974), Karpiscak (1976), Theroux (1976). Dolan et al (1977). Ruffner et al (1978), Suttkus ct al. (1978), Carothers et al (1979), and Carothers and Dolan (1982).

During our study, we sampled mammals at 50 localities along the river; there were 25 sites on the right bank and 25 on the left bank. General descriptions of many of these localities were pro- vided by Suttkus <'t al. (1978). The numbers of the localities in the following list correspond with numbers on the map (Figure 1).

List of Localities

1. Lee's Feriy. river mile 0. right bank.

2. 3.9 miles N Marble Canyon, river mile 2. right bank.

3. House Rock, river mile 17. right bank.

4. River mile 19. left bank.

5. River mile 21.8. right bank.

6. River mile 22. left bank.

7. River mile 26, left bank.

8. Stanton Cave, river mile 31.8, right bank.

9. Buck Farm Canyon, river mile 41, right bank.

10. President Harding Rapid, river mile 44. left bank.

11. Little Nankoweap. river mile .50. right bank.

12. Kwagunt Creek, river mile 56. right bank.

13. Kwagunt Rapid, river mile 56.5, left bank.

14. Lava Canyon, river mile 65.5, left bank.

15. Tanner Rapid, river mile 68. left bank.

16. Cardenas Creek, river mile 71. left bank. Cardenas Creek, river mile 71. right bank.

17. Unkar Rapid, river mile 72, right bank.

18. Granite Rapid, river mile 93.5. left bank.

19. Boucher Creek, river mile 9(i.5. left bank.

20. Crystal Creek, river mile 98.2, right bank.

21. Tuna Creek, river mile 99.3, left bank.

22. Lower Bass Camp, river mile 108.5, right bank.

23. River mile 1(19.5. right bank.

24. River mile 112. right bank.

25. River mile 114, right bank.

26. Elves Chasm, river mile 116. left bank.

27. River mile 119.5, left bank.

28. River mile 124. left bank.

29. Stone Creek, river mile 132. right bank.

30. Deer Creek Falls, river mile 136.2, left bank.

31. Overhang, river mile 137. left bank.

32. Backwater Camp, river mile 137.2. left bank.

33. Fishtail Canyon, river mile 139. right bank.

34. River mile 151.5. right bank.

35. Tuckup Canyon, river mile 164.5. right bank.

36. River mile 165. right bank.

37. National Canyon, river mile 166.5. left bank.

38. Fern Glen Canyon, river mile 168, right bank.

39. Mohawk Canyon, river mile 171.5, left bank.

40. Lava Falls Rapid, river mile 182, right bank.

41. River mile 1S3. right bank.

42. Whitmore Wash, river mile 1S8, right bank.

43. River mile 196, left bank.

44. Granite Park, river mile 209. left bank.

45. River mile 212.5. left bank.

46. 220 Mile Canyon, river mile 220. right bank.

47. Bridge Canyon dam site, river mile 2)38. left bank.

48. Scorpion Island, river mile 279.5, left bank.

49. Sand Point, river mile 291.5. left bank.

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Results

A checklist of the mammals encountered by us along the Colo- rado River in the bottom of the Grand Canyon is provided below. This list includes only those taxa of mammals from the study area for which we have either substantiated sight records or voucher specimens that are deposited in a museum. For details of the distribution of these forms in the area, as well as other general information, see the accounts of species that follow.

Checklist of Mammals Studied

ORDER CHIROPTERA Bats

Family Vespertilionidae (Vesperti

Myotis yumanensis My Otis thysanodes Myii t is cal ifornims Pipist)-elliw hrsperus Euderma maculatum Plecotus townse7uiii Idionycteris phyllotis Antrozovs pallidus

Family Molossidae (Molossid Bats)

Tadarida hrasiliensis

lionid Bats)

Yuma Myotis Fringed Myotis California Myotis Western Pipistrelle Spotted Bat

Townsend's Big-eared Bat Allen's Big-eared Bat Pallid Bat

Brazilian Free-tailed Bat

ORDER LAGOMORPHA Lagomorphs Family Leporidae (Hares and Rabbits) Sylvilagus audubomi Desert Cottontail

Lepus californwus Black-tailed Jack Rabbit

ORDER RODENTIA Rodents

Family Sciuridae (Squirrels)

Eutamias dorsalis A m m ospenn oph ihis hanisi i A mmospermophilus leucunis Spermophilus variegatus

Cliff Chipmunk Harris' Antelope Squirrel White-tailed Antelope Squirrel Rock Squirrel

Family Heteromyidae (Heteromyids)

Perognathusamplus PeriKj na t hus formosus Perognathus intermediiis Dipodomys memanri

Family Castoridae (Beavers)

Castor canadensis

Arizona Pocket Mouse Long-tailed Pocket Mouse Rock Pocket Mouse Merriam's Kangaroo Rat

Beaver

Family Cricetidae (New World Rats and Mice)

Reithrodontomys megalotis Peromyscus crem.icus Peromysats manicidatuji Peromyscus crinitus Peromyscus hoylii Peromyscus tniei Neotoma alhigula Neotoma lepida Neotoma devia

Western Harvest Mouse Cactus Mouse Deer Mouse Canyon Mouse Brush Mouse Pinon Mouse White-throated Woodrat Desert Woodrat Arizona Woodrat

ORDER CARNIVORA Carnivores

Family Canidae (Canids)

Canislatraiis Coyote

Urocyon cineredcirgcnteus Gray Fox

Family Procyonidae (Procyonids) Bnssarisciis (istutiis RingUiil

Family Mustelidae (Mustelids) Spilogale pntorius Spotted Skunk

ORDER ARTIODACTYLA Even-toed Ungulates Family Cervidae (Cervids)

CMncoileus hemionus Mule Deer

Family Bovidae (Bovids)

Ovw canademm Mountain Sheep

ORDER PERISSODACTYLA Odd-toed Ungulates Family Ekjuidae (Ex:iuids) Equus asinuii Domestic Ass

Species Accounts

Family Vespertilionidae

Myiitis yumanensis (H. Allen) Yuma Myotis

This species occurs from southwestern British Columbia south- ward across the southwestern United States, except for the central Great Basin, into Mexico to the Distrito Federal and throughout Baja California.

Myotis yumanensis ifumanensis (H. Allen)

The Yuma myotis ranges from western Nevada, extreme north- western Colorado and central Utah, and from southern Colorado southward to Durango and most of Baja California (Hall, 1981).

Ruffner et al. (1978) reported that this bat was distributed wide- ly along the Colorado River from Lee's Ferry to the Grand Wash Cliffs: they listed specimens from the vicinity of river mile 33 to 38 and from Havasu Creek. Suttkus et al. (1978) reported on speci- mens from river mile 41 and river mile 294. .5, which is south of the Grand Wash Cliffs. Hoffmeister (1971) stated that these bats were common at Phantom Ranch and in Havasu Canyon. On 22 August 1981, we found several dozen M. ifuiimiwmis roosting on the tops of vegas in an old house at Lee's Ferry; both adult and young bats were present.

Specimens examined, 43.— Coconino County: Lee's Ferry, river mile 0, right bank, 7: River mile 19, left bank, 2: Buck Farm Can- yon, river mile 41, right bank, 26; Cardenas Creek, river mile 71, left bank. 2; Lower Bass Camp, river mile 108.5, right bank, 1; Deer Creek Falls, river mile 136.2, left bank, 2; Backwater Camp, river mile 137.2, left bank, 1. Mohave County: Fern Glen Canyon, river mile 168, right bank, 1; Sand Point, river mile 294.5, left bank, 1.

Myotis tliyiianodes Miller Fringed Myotis

This bat occurs from southern British Columbia southward throughout the western and southwestern United States and into

Mexico to Chiapas. There is an isolated population in the Black Hills of South Dakota and adjacent parts of Wyoming and Nebraska.

Mjiiitix tlutsiiiKKlfx tlnjtfdiiiKlrK Miller

This sub.species ranges from southern British Columbia and throughout the western and southwestern United States, as noted above, and in Mexico to Morelos (O'Farrell and Studier, 1980).

Only a single specimen of the fringed myotis has been obtained along the Colorado River in the bottom of the Grand Canyon (Sut- tkus <■! III.. 1978).

Specimens examined, 1.— Coconino County; River mile 19, left bank, 1.

Miiotiii caHforiiicus (Audubon and Bachman) California Myotis

Tlie California myotis occurs from southwestern British Colum- bia southward across the western United States throughout Baja California and in Mexico to Chiapas. This species is absent from the central portion of the Great Basin.

Mijtitk califiiniicus Mepheusi Dalquest

This form ranges from western Nevada and adjacent California into northern Baja California, southwestern Sonora, western Arizona, northwestern New Mexico, and into western Colorado and southeastern Utah (Hall, 1981).

Hoffmeister (1971) and Ruffner rt al. (1978) considered this the most common myotis within the Grand Canyon. These bats were observed in a day roost near the mouth of Havasu Creek, and were found roosting in Stanton's Cave (Ruffner et al. 1978). We found these animals especially common in the upper portion of the area studied.

Specimens examined, 80.— Coconino County: Lee's Ferry, river mile 0, right bank, 4; River mile 19, left bank, 22; River mile 26, left bank, 1; Buck Farm Canyon, river mile 41, right bank, 19: Cardenas Creek, river mile 71, left bank, 4: Boucher Creek, river mile 96.5, left bank, 4: Lower Bass Camp, river mile 108.5, right bank, 21: River mile 112, right bank, 1; Deer Creek Falls, river mile 136.2, left bank, 1 : Backwater Camp, river mile 137.2, left bank, 3.

Pijmtnlhiti hrfip(')^ll.^< (H. Allen) Western Pipistrelle

This species occurs from southeastern Washington and eastern Oregon southward through much of California and adjacent western Nevada, and from the Great Salt Lake through Utah and western Colorado throughout the Southwest to Baja California and in Mexico as far south as Morelos.

PipL^trcUvA hcftpems hesperns (H. Allen)

This subspecies ranges throughout the Southwest, mostly west of the Arizona-New Mexico state line, and throughout Baja Cali- fornia and in western Mexico to Morelos (Hall, 1981).

The western pipistrelle is widely distributed all along the Colo- rado River in the bottom of the Grand Canyon. Hoffmeister (1971) and Ruffner ft al. (1978) commented that these were the most com- mon bats in the Grand Canyon. Frequently, these small bats were observed flying during the day over the river, expecially in narrow

portions of the canyon.

Specimens examined, 87.-Coconino County; Lee's Ferry, river mile 0, right bank, 1; River mile 19, left bank, 7; Buck Farm Can- yon, river mile 41, right bank, 16: Little Nankoweap, river mile 50, right bank, 3; Cardenas Creek, river mile 71, left bank, 6; Boucher Creek, river mile 96.5, left bank, 2; Lower Bass Camp, river mile 108.5, right bank, 9; Deer Creek Falls, river mile 136.2. left bank, 16; Overhang, river mile 137, left bank, 3; Backwater Camp, river mile 137.2, left bank, 7. Mohave County: River mile 183, right bank, 1; Granite Park, river mile 209, left bank, 9; Scor- pion Island, river mile 279.5, left bank. 6: Sand Point, river mile 294..5, left bank, 1.

Euderma macvlatum (J. A. Allen) Spotted Bat

This monotypic sjjecies ranges from south-central Montana and southern Idaho through Nevada and southeastern California to western Wyoming, Colorado, and New Mexico southward on the Mexican Plateau toQueretaro(Watkins, 1977).

Hoffmeister (1971) included the spotted bat in the list of mam- mals that may be present in the Grand Canyon National Park. Poche (1981) reported that these bats were fairly common in Fort Pierce Wash, which is on the Utah-Arizona border near the Nevada state line. A modern summary of the biology of the spot- ted bat was presented by Poche (1981).

On the morning of 19 June 1979, we captured a male E. macnlatiim in a mist net set across the upper end of a ravine at river mile 19, left bank. The animal was photographed and re- leased; it flew up the ravine and disappeared apparently into a crevice in the cliffs above the ravine where it was captured. The elevation at river mile 19. left bank, is 912 m (2,990 ft.) according to Ruffner et al. (1978); Reynolds (1981) found a specimen of this bat at an elevation of 3,230 m (10,600 ft.). To our knowledge, this is the first record of E. maculatiim in the bottom of the Grand Can- yon along the Colorado River and in the Grand Canyon National Park. In addition, this may be the lowest elevation recorded for the spotted bat in this portion of its geographic range.

Si^ecimens examined, 0.

Plecotim tommeiidii Cooper Townsend's Big-eared Bat

This species occurs from southern British Columbia throughout the western United States to Oaxaca. In addition, some popula- tions occur in eastern Oklahoma, southwestern Missouri, and northwestern Arkansas, as well as in West Virginia and Virginia. In the East, the species is distributed in the vicinity of caves; in the West, these animals are ?nore widespread in distribution.

Plecotus tounmendii pallescens (Miller)

Townsend's big-eared bats range from southeastern British Col- umbia through central Washington, Oregon, and California throughout the Great Basin, Rocky Mountains, and western Great Plains southward to Sonora, much of Chihuahua, and south- western Texas (Hall, 1981).

Plrriitii.^ tdii'ii.'ioidii is fairly common along the Colorado River in the Grand Canyon from river mile 19 to river mile 168. These animals were captured in mist nets at a total of eight places in the study area. The presence of a large colony of P. tnwmeridii in Stanton Cave, river mile 31.8, right bank, was discussed by Ruff-

ner and Carothers (1975) and Suttkus ft ai. (1978).

Specimens examined, 28.— Coconino County: River mile 19, left bank, 8: Stanton Cave, river mile 31.8, right bank, 5: Buck Farm Canyon, river mile 41, right bank, 2; Cardenas Creek, river mile 71, left bank, 4; Unkar Rapid, river mile 72, right bank, 2: Lower Bass Camp,' river mile 108.5, right bank, 4; Backwater Camp, river mile 137.2, left bank, 1. Mohave County; Tuckup Canyon, river mile 164.5, right bank, 1; Fern Glen Canyon, river mile 168, right bank, 1.

Idiiiinjcteriit phyUotis (G. M. Allen) Allen's Big-eared Bat

This species occurs from southern UUih and Nevada southward mostly on the Mexican Plateau to the Distrito Federal, Mexico (Hall, 1981).

Hoffmeister (1971) included Allen's big-eared bat in the list of mammals that may be present in the Grand Canyon National Park. Ruffner and Carothers (1975) reported a male /. phijlUitk taken at Shiva Temple, and another male taken at Basin Spring: both of these localities are within the Grand Canyon National Park.

On the morning of 26 August 1981, we obtained a male /. phyllotk from a mist net stretched across a small pool in Buck Farm Canyon, river mile 41, right bank. To our knowledge, this is the first specimen of this bat taken in the bottom of the Grand Canyon near the Colorado River.

Specimens examined, 1.— Coconino County: Buck Farm Canyon, river mile 41, right, bank, 1.

Anirozous; pnllidiis (Le Conte) Pallid Bat

This species occurs from southern British Columbia southward through Baja California, as well as across the Great Basin and on the Colorado Plateau, and southward in Mexico to Hidalgo.

Antnizoiu'i palliduit pallidit.'^ (Le Conte)

This form ranges throughout much of the Great Basin, the Colo- rado Plateau, southwestern part of the Great Plains, and to cen- tral Mexico (Hall, 1981).

Pallid bats are reported as being widely distributed in the Grand Canyon, especially in the northern portion (Hoffmeister, 1971, Ruffner ct al. 1978). However, Hoffmeister (1971) plotted only a single locality along the Colorado River for this species, Ruffner rt al. (1978) reported capturing these bats at four localities, and Suttkus rt al. (1978) had specimens from two localities.

Specimens examined, 11. —Coconino County: Lee's Ferry, river mile 0, right bank, 5; River mile 19, left bank, 3; Buck Farm Can- yon, river mile 41, right bank, 3.

Family Molossidae

Tadarida brasilievs'is (I. Geof. St.-Hilaire) Brazilian Free-tailed Bat

Brazilian free-tailed bats occur throughout about the southern one-half of the United States, the West Indies, Central America except for the Yucatan Peninsula, and much of South America.

Tadarida tirasilietuik mexkana (Saussure)

This subspecies ranges from about the Missouri River through- out the western United States southward in Mexico to Chiapas (Hall, 1981).

Hoffmeister (1971) postulated that this species probably oc- curred in many areas in the bottom of the Grand Canyon. Ruffner I't (\l. (1978) reported on specimens from five places in the Inner Gorge, all along the left bank of the Colorado River. Bat Cave, river mile 266 , was mined commercially for guano for several years: the guano deposits were made probably by Brazilian free- tailed bats. Suttkus ct al. (1978) reported that no bats were present in this cave when they visited it on 8 September 1976.

Specimens examined, 2.— Coconino County: Lee's Feriy, river mile 0, right bank, 1; Lower Bass Camp, river mile 108.5, right bank. 1.

Family Leporidae

Sylvilagus auduhomi (Baird) Desert Cottontail

The desert cottontail occurs from central Montana, Wyoming, and adjacent North Dakota, South Dakota, and Nebraska west- ward to the Pacific Coast and southward throughout Baja Cali- fornia and in Mexico as far as central Veracruz and Puebla.

Sylvilagus auduhanii arizonae (J. A. Allen)

Tliis form ranges from southern Nevada and adjacent western Utah to southeastern California and western Arizona through most of Sonora (Chapman and Willner, 1978).

Hoffmeister (1971) reported the desert cottontail as being abun- dant on the South Rim of the Grand Canyon, but no specimens were available from along the Colorado River in the bottom of the canyon. Ruffner et al. (1978) suggested that 5. aiidubonii may enter the Inner Gorge of the Grand Canyon. On 9-10 June 1980, several animals were seen and collected during the day on Scor- pion Island.

Sjjecimens e.xamined, 4.— Mohave County: Scorpion Island, river mile 279.5, left bank, 4.

Lepus calijornicua Gray Black-tailed Jack Rabbit

Except for part of the Central Valley, this species occurs throughout California and across the Great Basin from southern Washington and southwestern Montana southward throughout Baja Calfornia, and in the Great Plains from southern South Dakota into Mexico to Hidalgo.

Lepus califoniicKS deserticala Mearns

This subs]:)ecies ranges from southwestern Montana and southern Idaho through most of Nevada and adjacent western Utah southward through western Arizona and southeastern Cali- fornia into northern Baja California and Sonora (Hall, 1981).

We observed black-tailed jack rabbits in the vicinity of Lee's Ferry and on Scorpion Island. Because of its preference for open, brushy country, it seems that there are few suitable habitats for this species within the Grand Canyon. Hoffmeister (1971) reported L. califiiriiicu,<^ as common on the South Rim and uncommon on

the North Rim of the Grand Canyon. Ruffner ft al. (1978) sug- gested that this hare may enter the Inner Gorge on occasion. Specimens examined, 0.

Family Sciuridae

Evtamias dorsalis (Baird) Cliff Chipmunk

Cliff chipmunks are known from extreme southern Idaho, south- western Wyoming, northwestern Colorado, across much of Utah and eastern Nevada southward across Arizona and western New Mexico to eastern Sonora, western Chihuahua, and into northern Durango. An apparent isolated population occurs along the coast in central Sonora.

Eutamias dorsalis dorsalia (Baird)

Tills form occurs in central Arizona, western New Mexico, and in eastern Sonora and western Chihuahua into northern Durango (Hall, 1981).

According to Hoffmeister (1971), these animals "... are found not only along the edge of the South Rim but also down in the can- yon, as at Indian Garden and Havasu Canyon." Ruffner ct al. (1978) were unaware of any specimens from the inner gorge of the Grand Canyon, but they reported sight records from about five places on the left bank between river mile 27 and river mile 186. During our studies along the Colorado River, we have seen cliff chipmunks several times in the vicinity of river mile 19, left bank. On 24 August 1981, an animal was trapped at this locality; another chipmunk was taken on 20 June 1982. To our knowledge, these are the first specimens of E. d.nrmlis from the bottom of the grand Canyon along the Colorado River.

Specimens examined, 2.— Coconino County: River mile 19, left bank, 2.

Ammospermiiphihis hanisii (Audubon and Bachman) Harris' Antelope Squirrel

Harris' antelope squirrel occurs throughout southern Arizona, the southwestern corner of New Mexico, and northern Sonora. Throughout its range, this animal seems relatively wary and diffi- cult to observe closely, as compared with other ground squirrels.

Ammospermopkilm Imirisii harrisii (Audubon and Bachman)

This form is found in south-central Arizona, the southwestern corner of New Mexico, and north-central Sonora (Hall, 1981).

This species has not been recorded from within the Grand Can- yon (Hoffmeister, 1971), but it does occur along the east side of the lower Colorado River (Suttkus ct al, 1978); Cockrum (1960) exam- ined sj^ecimens from 4 mi SW Pierce Ferry. We found this antelope squirrel fairly abundant on Scorpion Island, river mile 279.5, left bank. This island, which was formed by the filling of Mead Reservoir, is just upriver from Pierce Ferry (sometimes referred to as Pierce Landing).

Specimens examined, 10.— Mohave County: Scorpion Island, river mile 279.5, left bank, 10.

Ammospermophil-ns leucurus (Merriam) White-tailed Antelope Squirrel

The white-tailed antelope squirrel ranges from southeastern

Oregon and southwestern Idaho southward through Baja Califor- nia, and occurs in the deserts of the Great Basin and on the Colo- rado Plateau in Nevada, Utah, western Colorado, northern Arizona, and northwestern New Mexico. A rather typical habitat seems to be rocks at the edges of sandy grasslands.

Ammmpermophihis leucimt.^ escalante (Hansen)

This form occurs in the northern Arizona Strip and adjacent southwestern Utah (Hall, 1981).

Hoffmeister (1971) considered that this species was primarily, but not exclusively, restricted to the Inner Gorge and the Grand Canyon proper. Ruffner, et al. (1978) referred to specimens taken at river mile 52-56, right bank, 66-71, left bank, 168, right bank, and 185.5-188, right bank. Mead and Phillips (1981) stated that this squirrel was found throughout the Grand Canyon. We were successful in obtaining specimens at only two localities along the Colorado River. Cockrum (1960) referred specimens from "N side Colorado R., Lees Ferry (Lee Ferry)" to A. I. cinmm.omeus. We agree with the comment by Armstrong (1979a) that "... popula- tions of antelope ground squirrels do not seem as distinctive as current nomenclature might lead one to imagine."

Specimens examined, 106.— Coconino County: Lee's Ferry, river mile 0, right bank, 105; River mile 21.8, right bank, 1.

SpermophUus variegahm (Erxleben) Rock Squirrel

Rock squirrels range from Utah, Colorado, and southeastern Nevada southward to Puebla. It seems that these animals are associated usually with coUuvial rubble in semiarid foothills and mountains.

SpermophUus variegatus grammurus (Say)

This subspecies occurs in southern Utah and adjacent Colorado southward through Arizona and New Mexico into Sonora and Chihuahua (Hall, 1981).

Tliese animals occur along the Colorado River above the Nevada- Arizona state line (Cockrum, 1960, Hoffmeister, 1971). According to Ruffner et al. (1978), rock squirrels are especially common at Havasu Creek. We spotted these animals frequently in the vicini- ty of river mile 19, left bank.

Si^ecimens examined, 4.— Coconino County: River mile 19, left bank, 2; Granite Rapid, river mile 93.5, left bank, 1; Elves Chasm, river mile 116, left bank, 1.

Spennophihus variegatus utah (Merriam)

This form is found in central and southwestern Utah, the Arizona Strip, and in southern Nevada (Hall, 1981).

Ruffner ft al. (1978) reported specimens from the vicinity of river mile 31. .5-35 and at Phantom Ranch, river mile 88. Except for Phantom Ranch, where these animals were seen frequently, rock squirrels seemed less common on the right bank than on the other side of the Colorado River. The difficulties of identifying to subspecies rock squirrels from each side of the Colorado River were mentioned by Hoffmeister (1971), Armstrong (1979a), and Hall (1981.)

Specimens examined, 2.— Coconino County: House Rock, river mile 17, right bank, 1. Mohave County: River mile 165, right bank, 1.

Family Heteromyidae

Perognathm amplux Osgood Arizona Pocket Mouse

Pcrinimithnu anijilii,^ is confined to north-central Arizona, an area adjacent to the Nevada-Arizona border, and south-central Arizona, as well as in northwestern Sonora.

FrnKinathNK amplioi pcrgmcilis Goldman

This subspecies is found in west-central Arizona, along the Nevada-Arizona border (Hall, 1981).

Hoffmeister (1971) did nut record this species from within the Grand Canyon. Cockrum (196(t) reported on a series of specimens that were collected near Pierce Landing, Arizona, in 1942. The current distribution and status of this subspecies in west-central Arizona seems unclear, especially since the filling of Mead Reservoir.

Specimens examined, 2.— Mohave County: Scorpion Island, river mile 279.5, left bank. 2.

Pc n iij fiat h iiti /(innii^u.'i Merriam Long-tailed Pocket Mouse

This species occurs in the Great Basin from the Great Salt Lake and northwestern Nevada southward along the west side of the Colorado River into northern Raja California.

Perognathusfonuusus domisaxensis Cockrum

This pocket mouse ranges from southern Utah to northern Arizona north of the Colorado River (Hall, 1981).

Since Cockrum (19.56) described this form, a considerable amount of information has become known about the distribution of long-tailed pocket mice in the Grand Canyon in particular and in northwestern Arizona in general (Hoffmeister, 1971, Ruffner ct al. 1978, Suttkus ct al. 1978, Hall, 1981). It was our impression that these animals were not at all common in the area studied.

Specimens examined, 2.— Coconino County: Lee's Ferry, river mile 0, right bank, 1; 3.9 miles N Marble Canyon, river mile 2, right bank, 1.

Perognathusformosus melanocaudus Cockrum

This subspecies occurs in the southern part of the Arizona Strip along the north side of the Colorado River (Hall, 1981).

Ruffner et al. (1978) reported specimens from about 12 localities in the bottom of the Grand Canyon. We found these mice most commonly at Unkar Rapid, river mile 72, right bank. See the com- ments above about the distribution of long-tailed pocket mice in the Grand Canyon. To our eyes these populations ofP.furmaiius do not seem as distinctive as current nomenclature leads us to imagine.

Specimens examined, 35.— Coconino County: Buck Farm Can- yon, river mile 41, right bank, 4: Little Nankoweap. river mile .50, right bank, 3; Cardenas Creek, river mile 71, right bank, 7: Unkar Rapid, river 72, right bank, 20; Fi-shtail Canyon, river mile 139, right bank, 1.

Perogmithvft ititermedivs Merriam Rock Pocket Mouse

Perogmithus interrnedius occurs in south-central Utah, central New Mexico, and southward into Sonora and Chihuahua.

FinigHdthiis inte.iine.dvns crinitus Benson

This form ranges from southern Utah into northwestern Arizona almost to the Nevada-Arizona border south of the Colora- do River (Hall, 1981).

All of our records of the rock pocket mouse are from below the confluence of the Little Colorado River with the Colorado River. Ruffner ct al. (1978) reported specimens from two localities above the Little Colorado River, and from l(i lalaces along the lower por- tion of the Colorado River. We found these animals especially common at Cardenas Creek, river mile 71, left bank, where they were trapjjed mostly among sand dunes. Specimens from our southernmost localities should be examined m(}re closely in con- nection with the determination of subspecific affiliations.

Specimens examined, 232.— Coconino County: Lava Canyon, river mile 65, left bank, 2; Tanner Rapid, river mile 68, left bank, 1; Cardenas Creek, river mile 71, left bank, 87; Boucher Creek, river mile 96.5, left bank. 6 ; River mile 119.5. left bank. 1; Deer Creek Falls, river mile 136.2, left bank, 30; Overhang, river mile 137, left bank, 9; Backwater Camp, river mile 137.2, left bank, 3; National Canyon, river mile 166.5, left bank, 1; Mohawk Canyon, river mile 171.5, left bank, 1; River mile 196, left bank, 3; Granite Park, river mile 209, left bank, 26. Mohave County: Bridge Canyon dam site, river mile 238. left bank, 51; Scorpion Island, river mile 279.5, left bank, 10; Sand Point, river mile 294.5, left bank, 1.

Dipudamyff mcmaiHi Mearns Merriam 's Kangaroo Rat

Merriam's Kangaroo rat ranges from western Nevada and adja- cent southeastern California across southern Arizona and New Mexico southward into Baja California. Sonora, and central Mex- ico to San Luis Potosi.

Dipodamys meniami menia.nii Mearns

This subspecies occurs in western Nevada, adjacent southeast- ern California, southern Arizona, and into northwestern Sonora (Hall, 1981).

Dipodomys memami was not reported from the Grand Canyon National Park by Hoffmeister (1971), who discussed some reasons why these kangaroo rats probably do not occur in the area. Ruff- ner ct (d. (1978) listed records from Grapevine Wash, river mile 274, left bank. On Scorpion Island, river mile 279.5, left bank, this kangaroo rat was the most common mammal that we encountered.

Si^ecimens examined, 65.— Mohave County: Scorpion Island, river mile 279.5, left bank, 62; Sand Point, river 294.5, left bank, 3.

Family Castoridae

Castor canadomiii Kuhl Beaver

Beavers are known from throughout most of the United States and Canada, except for parts of the arid Southwest, the southern Great Basin, and the peninsula of Florida. These mammals are restricted to areas with constant water supplies. Beavers were ex- tirpated from many areas of their natural range by fur trappers. Since 1900, some of these regions have been restocked with ani- mals not always of the same subspecies that had been extirpated.

Castor canadensi'i repentinus Goldman

This form occurs in the Colorado River drainage from the Tavaputs Plateau in Utah southward to the mouth of the Colorado River in the Sea of Cortez (Jenkins and Busher, 1979).

Ruffner et al. (1978) made a census of beavers by counting bank burrows along the Colorado River from Nankoweap Canyon to Kwagunt Creek; four burrows were observed in this 3-mile section of the river. Durrantand Dean (1959) estimated 10 active dens per river mile in Glen Canyon. Brazell et al. (1977) reported a total of 105 dens, 64 of them active, in Canyonlands National Park, Utah.

Beavers and their fresh signs have been seen by us from Lee's Ferry, river mile 0, to the vicinity of Fern Glen Canyon, river mile 168. Additional sightings of beavers in tributaries of the Colorado River were at Bright Angel Creek (Hoffmeister, 1971), Paria River (Suttkus et al.. 1978), and Little Colorado River (Ruffner et at.. 1978). The post-dam development of e.xlensive riparian habitat may have led to an expansion of beaver populations in the Grand Canyon (Carothers et al.. 1979). Brazell et al. (1977) reported that willows and cottonwoods were utilized extensively for food by beavers along the Green River and the Colorado River in Canyon- lands National Park: tamarisk was not used by beavers in this area.

Specimens examined, 0.

Family Cricetidae

Reithnidontiimys megalotis (Baird) Western Harvest Mouse

This species inhabits grasslands and shrublands in North Amer- ica from British Columbia and Alberta to Oaxaca and from In- diana to California.

Reithrodontomys megalotis megalotis (Baird)

This subspecies ranges from British Columbia throughout most of the Great Basin and the arid Southwest, and in Mexico to Guanajuato (Hall, 1981).

Hoffmeister (1971) referred to two localities in the bottom of the Grand Canyon for the western harvest mouse. This species was not common adjacent to the Grand Canyon in the Arizona Strip (Hoff- meister and Durham, 1971). Ruffner et al. (1978) reported specimens from four places along the right bank of the Colorado River. In the bottom of the Grand Canyon, these mice seemingly require rather mesic areas with dense ground cover (Ruffner et al... 1978, Suttkus et al. 1978).

Specimens examined, 3.— Coconino County; Buck Farm Canyon, river mile 41, right bank, 3.

Peromyseus eremicus (Baird) Cactus Mouse This species ranges from southern Nevada and adjacent south- western Utah southward thr(}ughout most of Baja California and to Sinaloa and San Luis Potosi.

Peromyscus eremicus eremiciis (Baird)

This form occurs from southern Nevada southward into Baja California and northern Sonora, as well as on the Mexican Plateau to Durango (Veal and Caire, 1979).

Durrant and Dean (1959) did not collect these mice in Glen Can-

yon. Merriam (1890) found that this species was the most common mammal in the Grand Canyon. Hoffmeister (1971) and Suttkus ct al. (1978) reported that the cactus mouse was the most ubiquitous Peromyscus that they encountered. This species was collected from nearly every available habitat in the Arizona Strip (Hoff- meister and Durham, 1971). Ruffner et al. (1978) reported specimens from a total of 61 localities in the Inner Gorge, and thought that the cactus mouse was the most widely distributed and the most abundant mammal there.

Specimens examined, 898.— Coconino County; Lee's Ferrv, river mile 0, right bank, 5; River mile 19, left bank, 77; River mile 22, left bank, 14; River mile 26, left bank, 2; Buck Farm Canyon, river mile 41, right bank, 61; President Harding Rapid, river mile 44, left bank, 2; Little Nankoweap, river mile 50, right bank, 7; Kwagunt Creek, river mile 56, right bank, 6; Kwagunt Rapid, river mile 56.5, left bank 12; Lava Canyon, river mile 65.5, left bank, 14; Tanner Rapid, river mile 68, left bank, 8; Cardenas Creek, river mile 71, left bank, 99; Cardenas Creek, river mile 71, right bank, 11; Unkar Rapid, river mile 72, right bank, 49; Boucher Creek, river mile 96.5, left bank, 26; Crystal Creek, river mile 98.2, right bank, 2; Tuna Creek, river mile 99.3, left bank, 5; Lower Bass Camp, river mile 108.5, right bank, 132; River mile 114, right bank, 4; River mile 119.5, left bank, 6; River mile 124, left bank, 2; Stone Creek, river mile 132, right bank, 5; Deer Creek Falls, river mile 136.2, left bank, 38; Overhang, river mile 1-37, left bank, 34; Backwater Camp, river mile 137.2, left bank, 35; Fishtail Canyon, river mile 139, right bank, 3. Mohave County; Tuckup Canyon, river mile 164.5, right bank, 17; National Canyon, river mile 166.5, left bank, 6; Fern Glen Canyon, river mile 168, right bank, 133; Mohawk Canyon, river mile 171.5, left bank, 4; Lava Falls Rapid, river mile 182, right bank, 7; River mile 183, right bank, 2; Whitmore Wash, river mile 188, right bank, 6; River mile 196, left bank, 4; Granite Park, river mile 209, left bank, 22; River mile 212.5, left bank, 2; 220 Mile Canyon, river mile 220, right