Antilocapra americana

Upperparts are reddish brown to tan; underparts, lower sides, rump, and two bands on the neck are white; neck has a short black mane; male has a black band along each side of the snout, a black patch on each cheek, and sometimes black bands on the neck; males and most females have horns (larger and usually forked in males; sheaths are shed annually); two toes on each hoofed foot; head and body length 100-150 cm, tail 8-18 cm, mass 36-70 kg (Nowak 1991).

Shape of the horns and annual shedding of horn sheaths are unique among North American ungulates. Differs from the bighorn sheep in having white bands on the neck and slightly curved horns rather than strongly curved horns. Differs from deer in having white lower sides rather than lower sides the same basic color as the upper sides; also, deer lack conspicuous white bands on the neck.

Grasslands, sagebrush plains, deserts, and foothills. Need for free water varies with succulence of vegetation in the diet. Birth and fawn bedding sites in a sagebrush-steppe community in south-central Wyoming were in dense shrub cover, but the tallest, most dense cover was avoided (Alldredge et al. 1991).

Usually in small bands. Large winter herds disperse in spring. Forms separate bachelor and female-kid groups in spring and summer. Males associate with females in late summer and early fall. High mortality in young is common (mostly predation).

Breeds mid-September to early October in north, late July to early October in south. Gestation lasts 240-250 days in north, shorter in south (e.g., 210-225 days in Texas). Births occur earlier in south than in north; April-May in Texas, mainly first half of June in Colorado (Fairbanks, 1993, J. Mamm. 74:129-135). Females give birth usually to twins (single fawns mainly from young females). Young are weaned by four months, but continue to follow mother during first winter. Some begin breeding at 1 year.