NPS Photo by D.A. Buehler

Pronghorn Antelope - Antilocapra americana
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Another interesting mammal that spends most of its time on the prairie is the pronghorn antelope. Pronghorns are true American natives, found nowhere else in the world. they have roamed the plains and deserts of North America for at least the last million years in substantially the same form. One can truly call this animal unique: he is the lone member of his family, Antilocapra americana, which literally means the "American goat-antelope." The pronghorn has exceptionally keen vision complemented by excellent hearing and sense of smell.

Both sexes have horns, but the female's are only tiny spikes and are rarely pronged as are the twelve to eighteen-inch horns of the male. The horn is made up of two parts: a bony core covered by a black outer sheath. This sheath is made up of a stiff, hair-like substance. Pronghorns are the only animals in the world who shed their horns annually. The outer sheath of the horn falls off each fall and grows back by the following summer.

NPS Photo by Jack O'Brien

Pronghorn's coloration matches that of the prairie

The coloration of the pronghorn varies from light tan to a rich brown with prominent white patches under the stomach and on the rump. In times of danger, the hairs of the rump can be held erect to produce, in the bright sunlight of the plains, a white flash visible for many miles. Along the neck there is a thick mane of dark brown to black hair. Pronghorn bucks have black patches on the lower jaw below the eye and a black mask extending back from the nose. These markings make it easier to distinguish the male from the female. No other animal is more strikingly beautiful than the pronghorn when he "poses" on the open plains.

NPS Photo by Tom Bean

Pronghorn's running gait

The running gait of the pronghorn is beautifully smooth and their powerful legs can carry them at a remarkable pace across the roughest kind of terrain. As the fastest North American mammal, pronghorns can reach speeds of 60 miles per hour. At high speed they cover the ground in great strides of 14 to 24 feet, and are known to run for long distances at speeds of 30 to 40 miles per hour.

Fall signals the beginning of the intensive mating season. The territorial bucks are especially aggressive in defending their areas. Brief fights develop between males and occasionally one is seriously injured. Ambitious bucks may develop harems of 3 to 8 or more does.

The young are born in late May or early June with about 60% of the births being twins. At birth, fawns weigh 5 to 6 pounds and lack the spots that are characteristic of deer and elk fawns. The newborn do not have an odor and instinctively lie motionless for hours. This is their main defense from predators such as bobcats, eagles, and coyotes.