NATIONAL PARK SERVICE Wildlife Portfolio of the Western National Parks

THE AMERICAN PRONGHORN, often called antelope, is a characteristic inhabitant of the open arid plains in the western United States. It is a graceful animal and shows a large degree of curiosity. In Yellowstone National Park I have found that I could sometimes decoy these animals to within camera shot by lying in the grass and kicking my heels up into the air.

The two outstanding characteristics of this species are the short, slightly curved horns and large yellowish-white rump patch. This rump patch is composed of long, white hairs which are controlled by the skin muscles and can be raised at will. In times of excitement these hairs stand stiffly erect like a pert chrysanthemum, and are used by the pronghorn as an alarm signal to warn the members of the band of approaching danger. Its rear position makes it particularly conspicuous in bright sunlight when the frightened animal dashes away across the plains. Both the male and female bear horns. Normally, horns are permanent structures; only antlers are shed and grown anew each year. However the antelope is an exception to this general rule amongst American big game, because its horn sheaths are shed annually.

The pronghorn has a total length of about 50 inches; short tail, about 5 inches long; height, at shoulder, from 34 to 36 inches. An average male weighs about 120 pounds. In color, it is a rich reddish brown and has a darker brown stripe extending across the midline of the neck.

During the fawning season, the male antelope frequently stands sky-lined on the ridges, keeping watch over females and young in the sagebrush plains below.

The antelope's greatest enemy is man. However, coyotes keep them active, and some young fawns undoubtedly are captured by these wild dogs. Golden eagles also have been known to swoop down and attempt to capture fawns when they strayed away from their places of concealment.

Pronghorns appear to be relatively free from disease. Instances of lung infection are known to exist. At Yellowstone National Park an autopsy performed on a doe to ascertain the cause of death revealed both the presence of lungworms and a hemorrhagic condition of the lungs.

In the far West, particularly in northeastern California, northern Nevada, and southeastern Oregon, there has been an increase in the number of these animals during the past several years, partly through the establishment of the Charles Sheldon Antelope Refuge in Nevada. Previously feared to be in danger of extermination, they have in Yellowstone National Park, through the protection afforded them by the National Park Service, increased their numbers to the carrying capacity of the range.

PHOTOGRAPH, LAMAR RIVER, YELLOWSTONE NATIONAL PARK, JUNE 26, 1930.