Ammospermophilus leucurus
(White-tailed Antelope Squirrel)


Order: Rodentia
Order Description:Rodents
Family: Sciuridae
Family Description: Chipmunks, Marmots and Squirrels

Description:
This ground squirrel holds its tail erect, almost over its back, when moving about its environment. This distinguishes it from other ground squirrels in Idaho. Its tail is distinctly white underneath, perhaps an adaptation that makes the tail an important signal to other ground squirrels close by. It is well established that deer, such as the white-tailed deer use their tail as a danger signal. Its upper body is buffyClick word for definition to cinnamon brown during the spring and summer, but tends to turn grayish in winter. It has a narrow white stripe on its side from its back to its hip. Their total length is about 7.5 to 9.5 inches 194-239 mm), tail length is 2 1/8 to 3 3/8 inches (54-87 mm) and they weigh 3 to 5 ˝ ounces (85-156 g).

Range:
From southeastern Oregon and southwestern Idaho, south to Nevada, most of Utah, western Colorado, northwestern New Mexico, northern Arizona, eastern and southern California, and Baja California.

Habitat:
Found in low, dry, deserts and foothills, in sandy to rocky soil, in alkali sinks, and in shrub steppeClick word for definition with sagebrush, greasewood, shadscale, creosotebush, or sometimes juniper. In Idaho, restricted to salt-desert shrub communities (shadscale, halogeton).

Diet:
Omnivore. Eats green vegetation, seeds, insects, and carrion. May sometimes prey on small, live vertebrates. Diet changes seasonally with availability of various foods. In Idaho, known to feed primarily on shadscale and halogeton leaves and grass seeds.

Ecology:
They are not known to aestivateClick word for definition, but they may hibernateClick word for definition in the northern part of their range only. They are active throughout day even on extremely hot days. On hot summer days they may rest in shaded areas or in their burrow during hottest part of day. They are also known to rub saliva on their head, apparently attempting to cool themselves during extremely hot weather. In winter, they often bask in the sun. They may become torpidClick word for definition as a last resort if exposed to cold temperatures. They cannot survive indefinitely without free (drinking) water, but they are capable of acquiring water from their food. They store food and they may forage in trees or shrubs. Their burrows are often under a shrub but can be in the open, and they often use abandoned burrows of the kangaroo rat. They ay use multiple burrows over a period of a few weeks. They are primarily solitary. They do not maintain exclusive territories, but they form dominance hierarchies. In a southern Nevada study, their densityClick word for definition ranged from 0.06 per 2.5 acres (1ha) in late spring, to 0.35 per 2.5 acres (1 ha) in fall, and their average home range was about 15 acres (6 ha). In Utah, their population densityClick word for definition varied widely over time. They are well adapted to water conservation and desert life.

Reproduction:
In southern Nevada, breeds February-June with peak in February-March. In southern California, mating occurs mostly during first 2 wk of March. GestationClick word for definition lasts 30-35 days in Nevada and California. litterClick word for definition size varies from 5-14 young (average 8). Female probably produces 1 litter/yr, possibly 2 in some areas. In southern California, young first appear on surface in mid-May, 1-2 wk before weaningClick word for definition at age 8 wk.

Conservation:
Status: Unprotected nongame species

Global Rank:

G5

State Rank:

S4

Important State References:
Johnson, D.R. 1961. The food habits of rodents on rangelands of southern Idaho. Ecology 42:407-410.


Photos by David L. Chesemore ©2001
Information written by Donald Streubel,© 2000
Map image provided by
Stephen Burton,© 2000
Design by Ean Harker©1999, 2000.