The question of whether antelope exist in Yellowstone National Park stems from a common misnomer dating back to early explorers. True antelope belong to the family Bovidae and are native only to Africa and Asia. The animal frequently sighted and often called the “American antelope” is the pronghorn, a species unique to the Western Hemisphere. The pronghorn is a native resident of the Greater Yellowstone Ecosystem.
Pronghorn Identification and Clarification
The pronghorn, Antilocapra americana, is the sole surviving member of its own taxonomic family, Antilocapridae. This classification makes it biologically distinct from true antelope, which are grouped in the Bovidae family with cattle and goats. The initial confusion arose because early explorers noted its resemblance to Old World gazelles.
The most telling physical difference is the horns of the males. Pronghorn horns are unique because they are branched, or “pronged,” and the outer keratin sheath is shed and regrown annually. True antelope horns are unbranched and retained for the animal’s entire life. Males also feature a distinct black patch of fur on the angle of the jaw, which aids in visual identification.
Habitat and Distribution in the Greater Yellowstone Ecosystem
Pronghorn favor open landscapes, such as the sagebrush steppe and grasslands of the Greater Yellowstone Ecosystem. They largely avoid the heavily forested, high-elevation core of Yellowstone National Park. The best place to view them within the park boundaries is the Northern Range, including areas like the Lamar Valley and the Blacktail Deer Plateau.
This region offers the windswept, low-snow conditions and abundant forage necessary for their survival during winter months. The Yellowstone pronghorn population undertakes one of the continent’s longest terrestrial migrations. These seasonal movements take them from summer ranges in the park to lower-elevation winter grounds around the Gardiner Basin and the Paradise Valley.
Unique Adaptations and Behavior
The pronghorn is the fastest land animal in the Western Hemisphere, capable of reaching speeds up to 60 miles per hour. This velocity is supported by oversized lungs, a large heart, and a windpipe that allows for immense oxygen intake. This speed is believed to have evolved to escape an extinct predator, the North American cheetah, dating back to the Pleistocene epoch.
Their survival in open country is aided by extraordinary eyesight, comparable to looking through 8x binoculars, allowing them to spot movement across vast distances. Unlike deer or elk, pronghorn are reluctant jumpers and prefer to crawl under obstacles. This behavior creates a conservation challenge, as traditional cattle fences are often too low for them to pass safely. Their diet consists mainly of tough forbs and shrubs like sagebrush, which are often toxic to other grazing animals.
Population Status and Conservation
The Yellowstone pronghorn population has historically faced challenges, including a low count of around 190 individuals in 2009. The herd has since rebounded, with recent counts placing the population near 450 to 500 animals. A primary factor limiting their growth has been high predation rates on fawns by coyotes in the open northern range.
The reintroduction of wolves has indirectly benefited the pronghorn by reducing coyote density, thereby improving fawn survival rates. Conservation efforts focus on maintaining and restoring their traditional migratory corridors, which were fractured by human development and fencing. Projects involve retrofitting or removing miles of barbed wire fences to create a safe clearance, allowing the pronghorn to follow their ancient migration paths.