Speed and excellent eyesight are two attributes of the pronghorn. Indigenous to western North America, these fleet-footed mammals are often called “antelope” though technically they are more closely related to giraffes than Old World antelopes. Their scientific name Antilocapra americana means “American goat-antelope,” however they are not related to either goats or African antelopes.
During the last 5 million years, 12 species of even-toed
ungulates (antilocaprid) roamed North America. Some were in existence when humans crossed the Bering Straits and entered North America, others had already gone extinct. Of the 12, only the pronghorn survived.
Known to Native Americans and 16th century Spanish explorers, Meriwether Lewis and William Clark are credited with first describing the pronghorn for science during their 1804-1806 Corps of Discovery expedition. Thinking these fleet animals were related to African gazelles, they referred to them as “goats” or “antelope.”
The common name pronghorn comes from the shape of the horns which bear a forward-facing tine. The horns curve inwards and are shaped like a lyre. Made up of flattened bone which is covered with a keratinous sheath, these sheaths are shed annually. Females have smaller horns than the males.
Though pronghorn may resemble deer at a distance, they are built more for speed than their distant relatives and are the fastest land mammal in North America. So why the need for speed? Scientists believe that pronghorn evolved with the American cheetah, an extinct predator that once preyed upon these creatures. Being able to outrun the cheetah over the long haul was a great survival advantage, one the animal still uses today to avoid danger.
During the summer, pronghorn may be observed feeding in grasslands and open country along Interstate 70 in the Cisco and Green River deserts or among the sagebrush and grasses along the road to the Needles Overlook. Here the animals roam in small family groups, feeding on shrubs, grasses and forbs. Males are usually solitary or live in small bachelor groups gathering together with their harems during the breeding season.
Young are born in late spring or early summer. Females will “stash” their young in sagebrush areas while the adult forages. The young rely on their camouflage and stealth to avoid detection by predators. An “abandoned” fawn is usually under the watchful gaze of their mothers and should be left alone if discovered. Another attribute that contributes to the fawns’ survival when they are newborns is that they are odorless at birth. They spend a little time with their mothers each day, joining the herd when they are about a week old but even at around four days old these youngsters can outrun a human.
Though an adult pronghorn can run faster than 60 miles per hour, their eyesight also helps detect predators. When alarmed, their white rump hairs engorge and this signals to other pronghorn that danger is near. A common sight is watching a group of pronghorn disappear over a distant hill with white rumps.
Though able to bound in long strides, pronghorn are jumpers like mule deer. They prefer to crawl under fences which has led to support of barbless wire as the bottom strand of a three or four-strand fence. This allows the pronghorn to safely pass while keeping livestock at bay “…where the deer and the antelope play.”