POCKET GOPHEES 135 



than those on hind foot; skin loose-fitting; fur short, smooth but not plush-like; coloration 

 uniform, light to dark brown, varying according to age as well as to species. Habits: 

 Fossorial; live in self-constructed burrows in ground, appearing above surface but 

 rarely. Workings : Low mounds of loose earth with crescentic or moraine-like topography 

 (pi. 28c), mouth of burrow being near one side and left plugged. 



Occurrence. — Common practically without interruption throughout the Yosemite sec- 

 tion up to timber line.n Most plentiful about margins of meadows and on semi-open, 

 timbered slopes; absent only in densest forests and on bare rock formations. Indi- 

 viduals work independently, though often in close proximity to one another. 



The characters upon which most emphasis is laid by systematists for separating the 

 species of pocket gophers have to do with the skull and teeth, and determination of 

 these requires preparation of materials and special technical knowledge. It does not 

 seem desirable to deal with these internal characters here; for them the reader interested 

 is referred to Bailey's Revision of the Pocket Gophers of the Genus Thomomys (N. Am. 

 Fauna, no. 39, 1915, U. S. Dept. Agr., Bur. Biol. Surv.). As to external characters our 

 pocket gophers, though much alike, do possess features of difference which are appre- 

 ciable. These consist in tone of color, general size, and relative size of ear. These 

 external features are here given. The sequence of species is from the west base of the 

 Sierras across the mountains to Mono Lake. 



Fresno Pocket Gopher, Thomomys bottae pascalis Merriam, a race occupying most 

 of the floor of the San Joaquin Valley, was found to enter the Yosemite section only 

 along the bottom lands of the Merced River around Snelling. There it was abundant, 

 and troublesome in gardens and alfalfa fields. This gopher is slightly the largest of the 

 five kinds, and it is palest in color of those on the west side of the Sierra Nevada. In 

 summer it is bright cinnamon-buff all over, save for whitish tail and feet and dull brown 

 around mouth; in winter, darker, snuff brown, paler underneath. Head and body 5% 

 to 6% inches (130-168 mm.), hind foot 1 to IVt inches (25-32 mm.), ear (from crown) 

 about 1/1 inch (5-7 mm.), weight 3 to 6 ounces (82-172 grams). In this race and the 

 next, maximum dimensions and weights are for males, minimum for females; but in the 

 other three species, the sexes differ in size little or not at all. 



Digger Pine Pocket Gopher, Thomomys bottae mewa Merriam, a race inhabiting 

 a long narrow north-to-south strip along the western flank of the Sierras, was found 

 in the Yosemite section to occupy very closely the Upper Sonoran Zone. We found it 

 from Lagrange and Pleasant Valley east to six miles east of Coulterville, El Portal, 

 and Pinoche Peak (at 5500 feet). This gopher is smaller than pascalis; its color tone 

 in summer is still brighter, more reddish, and in winter darker, almost blackish down 

 the middle of the back. Head and body 4% to 6 inches (120-153 mm.), hind foot about 

 1 inch (24-28 mm.), ear (from crown) slightly less than ^4 inch (6-7 mm.), weight 

 21/4 to 41/2 ounces (67-129 grams). 



Yosemite Pocket Gopher, Thomomys alpinus awahnee Merriam, occupying the 

 Transition Zone along the west flank of the Sierras, chiefly south of the Yosemite 

 section, was found to be the common gopher on the floor of Yosemite Valley, west to 

 Cascades. Outside of the Valley it has been recorded only from Sequoia. This gopher 

 is dark grayish brown both summer and winter, and nearly all the individuals examined 

 have more or less blotching of pure white on the under surface, especially around the 

 chin and on the chest. Head and body 5i/4 to 6 inches (132-150 mm.), hind foot 1 to 

 I'Ys inches (26-29 mm.), ear (from crown) about V^ inch (5-6 mm.). 



Sierra Nevada Pocket Gopher, Thomomys monticola monticola Allen. A species 

 whose range covers the higher parts of the central and northern Sierras. It inhabits 

 rather strictly the Canadian and Hudsonian zones of the Yosemite region. We found 

 it from Aspen Valley and Chinquapin eastward across much of the intervening territory 

 below timber line to Gem Lake. Highest point of actual capture, 10,350 feet, at Vogel- 

 sang Lake. This gopher differs from all the others in its finer, longer pelage and in its 

 larger, pointed ears; the color tone on the back is dark brown tinged with russet, with 

 lower surface dull buffy white; a slaty patch behind ear. Head and body 5 to 6 inches 

 (126-150 mm.), hind foot 1 to \\i inches (26-31 mm.), ear (from crown) about % inch 

 (8-9 mm.), weight 3% to 5% ounces (90-158 grams). 



Fisher Pocket Gopher, Thomomys quadratus fisheri Merriam. Occupies the western 

 parts of the Great Basin, and inhabits the arid east slopes of the Sierras and the territory 

 around Mono Lake, chiefly within the Transition Zone. We took specimens from Leevin- 

 ing Creek (at 9200 feet). Walker Lake, and Silver Lake, east to Mono Craters. This 

 is the smallest and palest colored of the five kinds; its ear is very small. Color a dull 

 pinkish cinnamon above, buffy white beneath; a dusky spot at base of ear. Head and 

 body 4% to 5% inches (117-146 mm.), hind foot about 1 inch (25.5-27 mm.), ear (from 

 crown) about % inch (3-5 mm.), weight 2% to 3% ounces (65-98 grams). 



