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 mph (90 km/h). The pronghorn is also known as the pronghorn antelope, but is not a true antelope, and its horns 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, USA. The Pronghorn's range extends from southern Saskatchewan and Alberta, 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 live primarily in grasslands but also in brushland and deserts. Pronghorn eat cacti, grasses, forbs and browse plants.
Pronghorn newborns weigh 5 to 9 lb (2 to 4 kg) and are grey in color. Adult male pronghorn weigh 100 to 130 lb (45 to 60 kg) while females weigh 75 to 100 lb (35 to 45 kg). 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 pronghorn have horns about 12 in (300 mm) long with a prong. Female horns are usually half that length 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 allowed them to recover to 2–3,000,000 pronghorn. Wolves, coyotes and bobcats are the major predators. Golden Eagles have been reported to prey on fawns.