The animal commonly called the American antelope is a unique species known as the pronghorn. These iconic prairie dwellers are a defining feature of the state’s vast open spaces and are the fastest land mammal found in North America. The species, scientifically named Antilocapra americana, thrives across Wyoming’s high-desert plains and sagebrush steppe. The pronghorn is often mistaken for its African and Asian counterparts due to historical naming conventions. The presence of the pronghorn is of great importance to the state, which manages the largest population of this animal in the world.
Pronghorn Versus True Antelope
The pronghorn is not a member of the Bovidae family, which includes true antelopes, cattle, and goats. Instead, the pronghorn is the sole surviving member of its own taxonomic family, Antilocapridae. This classification means the North American pronghorn is more closely related to the giraffe and the okapi than to any species of true antelope.
The misnomer “antelope” originated with early European explorers, such as Lewis and Clark, who noted its superficial resemblance to the Old World animals. This confusion is a classic example of convergent evolution. A major difference lies in their horns: true antelopes have permanent, unbranched horns, while the pronghorn is the only animal in the world to possess branched horns that it sheds annually, like antlers.
Population and Distribution Across Wyoming
Wyoming is the global stronghold for the species, hosting more than half of the world’s pronghorn population. Recent estimates place the total number of animals at approximately 320,000 individuals. These vast numbers are sustained by the state’s expansive, undeveloped landscape.
The animals are distributed across most of the open, lower-elevation regions of the state, primarily inhabiting grassland and sagebrush ecosystems. The Red Desert in south-central Wyoming is a particularly significant area, supporting one of the largest migratory herds in the lower 48 states, numbering between 40,000 and 50,000 animals. The Green River Basin in the southwest is another major habitat, critical for winter survival.
Pronghorn generally avoid the dense forests and highest alpine peaks of the mountain ranges, preferring the unobstructed visibility of the basins and plains. However, the integrity of these habitats is increasingly challenged by energy development and habitat fragmentation.
Incredible Speed and Migration
The pronghorn is the fastest land animal in North America, reaching 60 miles per hour. This unparalleled speed and the ability to sustain high velocities over long distances are evolutionary adaptations linked to outrunning now-extinct predators, such as the American cheetah. Unlike other ungulates, their legs are built for running, not jumping, which is why they prefer to crawl under fences rather than leap over them.
Many pronghorn populations undertake one of the longest terrestrial migrations in the continental United States to survive the harsh winters. A famous example is the “Path of the Pronghorn,” a historic route extending up to 150 miles between the Upper Green River Basin and Grand Teton National Park. This corridor was the first federally designated migration corridor in the country.
During these long-distance movements, the animals travel between nutrient-rich summer grazing areas and lower-elevation winter ranges where forage is more accessible. The preservation of these migration routes is a major conservation focus, requiring the protection of key bottlenecks and the modification of fences to ensure the herds can complete their movements.