|Subspecies|| A. a. americana|
A. a. mexicana
A. a. oregona
A. a. peninsularis
A. a. sonoriensis
The pronghorn (Antilocapra americana) is a species of hoofed mammal native only to the grassland areas of North American, and is the only surviving member of the family Antilocapridae. Once as numerous on the plains as bison, their numbers were severely-reduced through over-hunting and the placement of cattle fencing; they have since rebounded, but with three subspecies listed as endangered.
Pronghorns are small ruminants, similar in appearance to antelopes yet unrelated, standing 2.5-3.5 feet at the shoulders, and weighing in at 105-120 pounds. Males are slightly larger than females. The coat is a tawny-brown, with white underbelly and rump; males are characterized by having a black blaze on the muzzle and a black chin patch at the nape of the neck. Males bear horns up to 14 inches long, curling backward at the apex, with a small single "prong" jutting forward, hence the name of the animal. Females bear a short spike up to four inches long.
It is the horns which the pronghorn apart from other horned mammals. Like antelopes and goats (to whom they are distantly-related), pronghorns have a horn made of keratin - the same material which make up hair, nails, and hoofs - over an internal, bony core. Unlike antelopes, the horn is hollow, and like the bony antlers of deer they are shed in late summer after the breeding season.
The eyes are extremely large and sensitive; pronghorns are alert animals and have been known to detect movement up to four miles away. The neck is massive in both sexes, containing a windpipe that is "oversize" for such an animal, again differentiating it from true antelopes, and enabling the pronghorn to gulp large amounts of air while on the run. Pronghorns are considered the fastest mammal on earth over a sustained distance, capable of sprinting to 60 miles an hour over a course of a hundred yards, and up to 50 miles an hour over several miles; by comparison, the fastest mammal over a short distance - the cheetah - can do up to 70 miles per hour, but quickly tires out after one hundred yards.
Pronghorns are an open plains mammal, predominantly found in the Great Plains regions of the western United States and southern Canada. Three subspecies are found in the scrub and desert regions of Arizona and Mexico. They prefer low vegetation, no higher then about thirty inches, as they are watchful for predators.