Mammals of the Grand Mesa, Colorado

Part 1

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UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Volume 9, No. 16, pp. 405-414, 1 fig. May 20, 1959

Mammals of the Grand Mesa, Colorado

SYDNEY ANDERSON

UNIVERSITY OF KANSAS LAWRENCE 1959

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson

Volume 9, No. 16, pp. 405-414, 1 fig. Published May 20, 1959

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED IN THE STATE PRINTING PLANT TOPEKA, KANSAS 1959

27-7472

Mammals of the Grand Mesa, Colorado

SYDNEY ANDERSON

The Grand Mesa of Colorado is a westward extension of the mountains of central Colorado, standing more than five thousand feet above the valleys of the Colorado and the Gunnison rivers. To certain montane mammals the mesa is a peninsula of cool, moist, forest surrounded by inhospitable, hot, dry, barren lowland.

Few mammals previously have been preserved or reported from the Grand Mesa. Of the species here reported, Warren (1942, The Mammals of Colorado, Univ. Oklahoma Press) mentioned only four from the counties in which the Grand Mesa is located. Twenty-two species are here recorded from the Grand Mesa, and two localities below the rim of the Mesa on the north slope, on the basis of specimens preserved, and five additional species on the basis of observations. Many of these species are limited to a montane habitat or find their optimum conditions there. The known geographic ranges of some subspecies are extended westward.

Specimens and notes were obtained by members of a field party from the Museum of Natural History led by Dr. Harrison B. Tordoff. The party, including also R. Gordon Cliffgard, John M. Legler, Olin L. Webb, and Glen E. Woolfenden, was in the area from June 17 to July 5, 1954, and obtained all of the specimens listed excepting those from 28 miles east of Grand Junction (Sect. 29, T. 11S, R. 95W), Mesa County, that were obtained from June 13 to July 2, 1956, by Phillip M. Youngman, and those from Land's End Road that were obtained on May 13 and 14, and on October 1, 1948, by D. A. Sutton.

Localities designated by numbers in the accounts to follow are listed in the legend for Figure 1. Localities 1 and 3 lie below the rim of the Mesa on the north side. Catalogue numbers are of the Museum of Natural History of the University of Kansas, unless noted otherwise.

=Sorex cinereus cinereus= Kerr.--Two male (59642-59643) Masked Shrews weighing 4.8 and 4.9 grams were trapped on June 17 at locality 10, and a nonpregnant female (59644) was trapped on June 26 at locality 6. Sorex cinereus seemed to be less abundant on the Mesa than Sorex vagrans; more individuals of S. vagrans than of S. cinereus were trapped on June 17 at locality 10 and on June 26 at locality 6, and S. vagrans was trapped at three localities where no S. cinereus was obtained.

(1) 2 mi. N, 9 mi. E Collbran, 7000 ft., Mesa County. (2) Land's End Road to Grand Mesa, 6800 to 8050 ft., Mesa County. (3) 3 mi. E, 4 mi. S Collbran, 6800 ft., Mesa County. (4) 3 mi. E, 9 mi. S Collbran, 10,200 ft., Mesa County. (5) 5-1/2 mi. E, 11-1/2 mi. S Collbran, in Delta County. (6) 5-1/2 mi. E, 12 mi. S Collbran, 9600 to 10,400 ft., in Delta County. (7) 28 mi. E Grand Junction (Sec. 29, T. 11S, R. 95W), Mesa County. (8) 6 mi. E Skyway, 10,000 to 10,500 ft., in Delta County. (9) 7 mi. E Skyway, in Delta County. (10) 8 mi. E, 1/2 mi. S Skyway, 9500 to 10,200 ft., in Delta County. (11) 8 mi. E, 3/4 mi. S Skyway, 10,200 ft., in Delta County. (12) 8 mi. E, 1 mi. S Skyway, 10,000 to 10,200 ft., in Delta County. (13) 8 mi. E, 1-1/2 mi. S Skyway, 8500 to 9600 ft., in Delta County. (14) 8 mi. E, 2 mi. S Skyway, 9000 ft., in Delta County. (15) 8 mi. E, 2-1/2 mi. S Skyway, 9600 ft., in Delta County. (16) 1 mi. S, 4 mi. W Skyway, 10,200 ft., Mesa County.]

=Sorex vagrans obscurus= Merriam.--Fifteen specimens of the Vagrant Shrew (59645-59655, 59665-59668) were trapped in Delta County from localities 6, 10, 12, 13, and 14. The fourteen specimens having skulls fell into two distinct age-classes based on wear of the teeth as described by Findley (1955, Univ. Kansas Publ., Mus. Nat. Hist., 9:8); 5 were in the younger group and 9 in the older group. Weights in grams of the younger shrews were 4.6, 5.5, 5.7, 5.8, and 6.4; weights of the older shrews were 6.4, 6.8, 7.3, 7.4, 7.5, 8.0, 8.3, and 8.8. One of the seven females was lactating; none contained embryos.

=Sorex palustris navigator= (Baird).--Six Water Shrews (59633-59638) were trapped in Delta County at localities 10, 13, 14, and 15. The one specimen from locality 10 was trapped on June 17; all others were taken on June 21. None was pregnant or lactating. Two are young, weighing 11.0 and 12.9 grams; the other four are older, weighing 16.6, 17.0, 19.2, and 21.5 grams.

=Myotis evotis evotis= (H. Allen).--One female Long-eared Myotis (59671), containing no embryos, was shot at dusk on July 2, at locality 3, which is below the rim of the Mesa.

=Myotis volans interior= Miller.--One female Long-legged Myotis (70016), containing no embryos, was shot at locality 7 on July 1, 1956.

=Ochotona princeps figginsi= J. A. Allen.--Six specimens of the Pika (59672-59675, 70018-70019) from localities 5, 6, 7, 8, and 9 extend the known range of the subspecies approximately 55 miles to the westward from Irwin in Gunnison County. Each of two females taken on June 18 and 26 contained three embryos, which measured 20 millimeters in the latter; a third female on June 29 contained two embryos 35 millimeters in length.

=Lepus americanus bairdii= Hayden.--No Snowshoe Rabbit was taken, but one individual was observed by H. B. Tordoff on June 18, 1954, at locality 8. Droppings of a large lagomorph were seen in the woods, and tracks were seen in the snow.

=Marmota flaviventris luteola= A. H. Howell.--The seven specimens of the Yellow-bellied Marmot (59731-6, 70022, four adult and two young, each a skin and skull, and one skull only of an adult) are referable on the basis of size, color, and locality as discussed by Warren (1936, Jour. Mamm., 17:394) to M. f. luteola. The total lengths in millimeters are as follows: young male 582; adult males 640, 655; young females 460, 520; adult female 630. The color and condition of the pelage is the same in all the specimens except that the two largest males are much more worn and show irregular patches of new hair on the back, and the two young females are paler especially on the back and tail. These marmots were taken at localities 4, 7, 8, 10, and 16.

=Spermophilus lateralis lateralis= (Say).--Eleven specimens of the Golden-mantled Ground Squirrel (59748-59756, 59763-59764) were taken at localities 1, 3, and 4. Young were born before late June; three young of the year were taken at locality 3 on June 29 and 30, and none of the adult females taken at locality 1 (1 female) and at locality 4 (3 females) was pregnant. Most adults of both sexes at all elevations represented (6800 to 10,200 ft.) showed molt in progress and proceeding from anterior to posterior. All specimens were obtained from June 25 to July 4.

Part 2

=Spermophilus variegatus grammurus= (Say).--Three Rock Squirrels (59738-59739, 59742) were obtained at locality 3. One of these specimens was a skull found near a wood rat nest. The other two were nonpregnant females; the adult measured 485 millimeters in total length, and the younger individual measured 413 millimeters. The two skins are characteristic of S. v. grammurus in their paleness.

=Eutamias minimus consobrinus= (J. A. Allen).--The 63 specimens of the Least Chipmunk (59770-59824, 60105-60108, 70024-70025, and nos. 5194 and 5196 in Univ. of Colorado Museum) were taken at localities 2, 3, 4, 6, 7, 8, 10, 13, and 15. The reproductive condition at time of death had been noted for 20 females obtained from June 17 to July 2 at elevations from 9500 to 10,400 feet. Eleven of these had no embryos, but six have mammae that are still prominent on the dried skins and may have had litters prior to their capture. Nine females contained embryos, numbering 3 in two specimens, 5 in four specimens, 6 in two specimens, and 7 in one specimen.

=Eutamias quadrivittatus hopiensis= Merriam.--Four specimens of the Colorado Chipmunk were obtained by D. A. Sutton at locality 2, at 6800, 6900, 7175, and 8050 feet elevation. All are males taken on May 13 and 14, 1949; the specimens bear numbers 5197, 5198, 5199, and 5201 in the collection of the University of Colorado Museum.

=Thomomys talpoides fossor= J. A. Allen.--The 27 specimens of the Northern Pocket Gopher (59840-59849, 70086-70102) were trapped at localities 3, 6, 7, 10, 11, and 13. The eight skins from locality 7 differ from those from the other localities on the Mesa in being uniformly duller in color dorsally. No significant difference in size or cranial characters was observed. Specimens assigned to T. t. fossor, in the collection of the Museum of Natural History, from other localities in Colorado differ in color from any of the specimens from the Grand Mesa. Until larger numbers of Thomomys talpoides from other localities in Colorado and from the type locality of T. t. fossor, stated to be at Florida, in southern Colorado, have been studied, the specimens from the Grand Mesa seem best referred to T. t. fossor. Three females from localities 7, 10, and 11 contained embryos (2, 4, and 5 in number), and seven other females from localities 6 and 7 show distinct mammae on the dried skins or were recorded by the collectors as lactating.

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