The Pronghorn (Antilocapra americana) is the only surviving member of the family Antilocapridae, and the fastest land animal in North America running at speeds up to 54 miles per hour (90 km/h). The Pronghorn is also known as the Pronghorn Antelope but unlike the hollow horns of true antelope, the horns of a Pronghorn are made up of a hairlike substance that grows around a bony core; the outer sheath is shed annually.
Pronghorn were brought to scientific notice by the Lewis and Clark Expedition which found them in present South Dakota. The Pronghorn's range extends from southern Saskatchewan and Alberta in Canada to Sonora and Baja California in Mexico. They live on both sides of the Rocky Mountains. Their eastern extent is generally bounded by the Missouri River in the United States. The subspecies known as the Sonoran Pronghorn (Antilocapra americana sonoriensis) occurs in Arizona and Mexico.
Pronghorn newborns weigh 5-9 pounds and are grey in color. Adult male Pronghorn weigh 100-130 pounds while females weigh 75-100 pounds. The main color of adults is brown or tan, with a white rump and belly and two white stripes on the throat. A short dark mane grows along the neck, and males also sport a black mask and black patches on the sides of the neck.
Male Pronghorns have horns about 12 inches long with a prong. Female horns are usually half the length of male horns and do not have a prong.
By 1908, hunting pressure had reduced the Pronghorn population to an estimated 20,000. Protection of habitat and hunting restrictions have made Pronghorn widespread again. Wolves, Coyotes and Bobcatss are the major predators. Golden Eagles have been reported to prey on fawns.