Natural History of the Ground Squirrels of California/Key to the Ground Squirrels of California

by Joseph Grinnell and Joseph Dixon

 

KEY TO THE GROUND SQUIRRELS OF CALIFORNIA.

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1. Size large: body alone more than 9 inches (228 mm.) long; tail more than 6 inches (152 mm.), not counting hairs; ears tall and rather pointed; tail bushy.

2. A blackish brown wedge-shaped patch on middle of back between shoulders Douglas Ground Squirrel (p. 52).

2'. No blackish patch on back.

3. Tail longer: without hairs, about 8 inches (203 mm.); no sharply defined triangular whitish patch on each shoulder Rock Squirrel (p. 58).

3'. Tail shorter: without hairs, 7½ inches (190 mm.) or less; a more or less sharply defined triangular whitish patch on each shoulder.

4. Size larger: body alone more than 10¾ inches (273 mm.) long; general tone of coloration darker Catalina Island Ground Squirrel (p. 49).

4'. Size smaller: body alone less than 10¾ inches (273 mm.); general tone of coloration lighter.

5. Coloration pale in general tone, near light cinnamon-drab; shoulder patches clear silvery white and more extensive Fisher Ground Squirrel (p. 44).

5'. Coloration somewhat darker, near wood brown; shoulder patches duller white and less extensive California Ground Squirrel (p. 9).

1'. Size medium or small: body alone less than 9 inches (228 mm.); tail less than 6 inches (152 mm.), not bushy; ears low and rounded, or else reduced to mere rims.

6. Body with conspicuous lengthwise stripes; coloration varied.

7. One white stripe on each side of body; under side of tail conspicuously white; head not more or less yellowish or coppery.

8. Smaller: body alone 6 inches (152 mm.) or less; general coloration grayish drab Desert Antelope Ground Squirrel (p. 94).

8'. Larger: body alone 6¼ inches (158 mm.) or more; general coloration light clay color.

9. Size slightly greater; tone of color slightly darker, more deeply clay color Nelson Antelope Ground Squirrel (p. 103).

9'. Size slightly less; tone of color slightly paler, more buffy Los Baños Antelope Ground Squirrel (p. 110).

7′. Three stripes on each side of body, one white and two black; head more or less yellowish or coppery.

10. Tail longer: without hairs, about 3½ inches (89 mm.).

11. Tone of coloration lighter; middle of back more of an ashy brown Inyo Golden-mantled Ground Squirrel (p. 89).

11'. Tone of coloration darker; middle of back more of a cinnamon-brown Sierra Golden-mantled Ground Squirrel (p. 83).

10'. Tail shorter: without hairs, about 3⅛ inches (79 mm.) San Bernardino Golden-mantled Ground Squirrel (p. 92).

6'. Body without any stripes: general coloration nearly or quite uniform.

12. Size larger: body alone more than 7 inches (178 mm.).

13. Larger: body about 8½ inches (216 mm.); middle of back not bright reddish-brown, but grayish-brown Oregon Ground Squirrel (p. 59).

13'. Smaller: body about 7+⁴⁄₅ inches (198 mm.); middle of back bright reddish-brown Belding Ground Squirrel (p. 67).

12'. Size smaller: body alone less than 7 inches (178 mm.).

14. Tail round and relatively long: over 3 inches (76 mm.).

15. Tone of coloration paler, light pinkish-cinnamon Yuma Round-tailed Ground Squirrel (p. 76).

15'. Tone of coloration darker, wood brown Death Valley Round-tailed Ground Squirrel (p. 80).

15". Tone of coloration medium, grayish-brown or avellaneous Palm Springs Round-tailed Ground Squirrel (p. 81).

14'. Tail flat-haired and relatively short: under 3 inches (76 mm.).

16. Under side of tail pinkish-buff; rim of ear distinct though low Stephens Soft-haired Ground Squirrel (p. 73).

16'. Under side of tail white; rim of ear scarcely discernible above general surface of head Mohave Ground Squirrel (p. 75).

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Note.—Figures indicating page numbers refer to folios at foot of pages.