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Antilocapra americana; Although its scientific name means "American goat-antelope," the pronghorn is not directly related to either goats or antelopes.
Looking somewhat like a deer, the pronghorn is about 4-1/2 feet long, stands about 3-1/2 feet at the shoulder, and weighs 90-150; males are heavier than females. Overall color is tan to reddish brown, with white markings on the face, neck, stomach and rump. The neck markings are white stripes. The rump has extra long white hairs that the pronghorn can stick up when scared. Males have a broad black mask that runs from their eyes down their snout to their nose and black neck patches; females lack the black markings.
The most noticeable features of pronghorns are also the source of their common name. Both males and females have a pair of horns on the top of the head. The females horns are small, usually only a bump, but those of the male are around 10-12 inches long. They also have a unique shape, because unlike other ungulates, a pronghorns horns point backwards. The horns extend straight up and then curve towards the rump. At the front of the horn is a small notch or prong that points forward. The pronghorn's horns are also unique in that they are neither true horns nor true antlers. True antlers are made of bone and shed each year, while true horns are made of compressed keratin that grows from a bony core and are never shed. The sheath of the pronghorn's horn is made of keratin, but the horns shed yearly. True horns also have only one point, not the prongs or forks that antlers have. The pronghorn is, therefore, the only animal in the world with branched horns, as well as the only one that sheds its horns each year.
The pronghorn is also the fastest animal in the Western Hemisphere, and the second fastest land mammal in the world, after the cheetah. Not only can it attain speeds of over 53 miles per hour (compared to the cheetah's top speed of 70 mph), it can run at speeds of 30-40 mph over long distances (while the cheetah can only run at top speed for a few hundred feet). Although it can easily clear up to 20 feet in one bound while running, the pronghorn is not good at jumping over obstacles (such as fences).
Excellent eyesight allows the pronghotn to spot a threat up to four miles away.
Distribution and Habitat
Pronghorns once roamed in huge herds from southern Canada to northern Mexico. Today, however, they are mainly found in Wyoming, Montana, northeastern California, southeastern Oregon, Nevada, Utah, Colorado, Arizona, and New Mexico. They inhabit open plains, fields, grasslands, brush, deserts, and basins.
The migration of pronghorns depends entirely on geography. Some do not need to migrate because the nearby land has plenty of food all year long, but one Wyoming herd undertakes an annual roundtrip migration of about 300 miles. The only North American land animal to cover more ground in a migration is the caribou. Other herds in the northern plains also migrate, but usually cover much shorter distances.
Males have breeding territories with a group of females that they defend against other males. Fighting between males can become very heated, with aggressive movements and even physical combat, and serious injury is a very real possibility.
Breeding takes place in September and October. Pronghorn have a longer gestation period than typical North American ungulates, averaging eight months, and twins are common. The does seek time and space alone to give birth and care for their offspring. The newborns can take their first wobbly steps just 30 minutes after birth, and can outrun humans by their fourth day. The mother keeps her fawn(s) hidden in tall prairie grasses, coming back to nurse every few hours. The fawns will join the herd when they are about a week old, begin grazing at about three weeks, are weaned at about twelve weeks, and are completely independent at about a year. Females reach sexual maturity at about two years, males at about age three.
Pronghorns dine on grasses, forbs, and cactus in the summer, while sagebrush and other available plants make up their winter diet. They receive most of their water from the plants they eat, but will take advantage of fresh water when available.
Pronghorns live in herds that change in size depending on the season. In the summer, females and their young will gather in bands of less than a dozen individuals, young males less than two years old form bachelor herds, and breeding males establish individual territories. In the winter, the herd will include males and females and can include hundreds of pronghorns.
Most active at dawn and dusk, pronghorns rarely close their eyes to sleep because they must remain alert to any possible danger.
If a pronghorn spots a predator, it raises its white rump hairs so that the white patch can be seen by other pronghorns. Although running away is the typical response to danger, a pronghorn may attack with its sharp hooves if cornered.
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This page was last updated on October 07, 2017.