Mammals: Pronghorn

Range: western North America Habitat: prairie and desert

One of a kind

The pronghorn is an original native American. It has no close relative on this or any other continent. This interesting animal goes by many names: pronghorn antelope, prongbuck, and American antelope. The pronghorn is often called an "antelope," and it does look similar to many antelope species. However, it is different enough to be classified in its own family, Antilocapridae. Read on to learn more about this one-of-a-kind critter!

Horns or antlers?

The horns of the pronghorn help make it unique: a cross between horns and antlers, with qualities of both. True antlers are made of bone and are shed each year; true horns are made of compressed keratin that grows from a bony core and are never shed. The horns adorning the pronghorn are neither true horns nor true antlers: the sheath is made of keratin but the horns are shed yearly. True horns have only one point, not the prongs or forks that antlers have. However, the male (buck) pronghorn's horns can grow to be 10 inches (25 centimeters) long with a forward-facing prong, or fork, giving the animal its name: pronghorn. Female pronghorn (called does) also have horns, but they are much smaller than the males', growing up to 6 inches (15 centimeters) long. Pronghorn are the only animals in the world that have forked horns that shed each year!

Home, home on the range

Pronghorn are well designed for prairie life. They have great adaptations for spotting and getting away from predators, such as wolves, coyotes, bobcats, and golden eagles. Pronghorn have very large eyes to help them see predators. Scent communication allows them to mark territories and warn others of danger. Bucks have nine scent glands and does have six. Glands beneath the ears help to mark territory during breeding time, but the glands on the rump are very important when danger is near: if a pronghorn sees a predator, it releases an alarm odor from these glands while the white fur on its rump stands up. This sends a message by both sight and smell to let other pronghorn know of the danger. A pronghorn may defend itself or its baby (fawn) by striking out with its hooves or by using its horns against a predator.

Sprinting specialists

If a predator does successfully sneak up on a pronghorn, its amazing running skills come into action. Pronghorn have been known to reach speeds of up to 53 miles per hour (86 kilometers per hour). This is not much slower than the fastest land mammal in the world, the cheetah. However, the pronghorn can maintain high speeds much longer than the cheetah can: 36 miles per hour (58 kilometers per hour) for 4 miles (6 kilometers). The pronghorn's hooves have two long, pointed toes that are cushioned to help take the shock when running at high speeds. Although they are excellent runners, pronghorn are not very good jumpers: if they come across a fence they will often go under it.

Family time

During fall and winter, pronghorn live in large, loosely organized herds of up to 1,000 individuals. Breeding takes place in September and October, with bucks defending and marking territories. Often, more dominant bucks will have better territories with better food supplies to attract the does. Pronghorn have a longer gestation period than typical North American ungulates, averaging eight months. It is common for a mother to have twins. Fawns are born in late spring, when the large herd breaks up into smaller groups. By two days of age, the fawn is able to run faster than a horse, if needed. The mother keeps her fawn hidden in tall prairie grasses until it is 21 to 26 days old, coming back to nurse her baby every few hours.

Grocery store on the prairie

Pronghorn are most active at dawn and dusk as they browse and graze on a variety of plants. They will eat the nonwoody flowering plants first, if available, and also eat shrubs, grasses, cactus, and domestic crops, depending on the time of year. Shrubs are very important in wintertime, and pronghorn use their front feet to dig for food buried in the snow. The pronghorn's teeth grow continuously because they wear down as they grind their food. At the Zoo, alfalfa pellets, hay, and fresh vegetation are provided.

Pronghorn and people

Early travelers to America's West told of pronghorn herds dotting the plains as far as the eye could see, more numerous than bison. It was estimated that there were about 100 million pronghorn and 65 million bison, providing settlers with plenty of meat and hides. But as more people arrived in the West, the pronghorn's habitat and food supply was reduced. By 1920 there were only about 13,000 pronghorn left. Part of this major decline was due to hunting. Early settlers would tie handkerchiefs to poles and wave them in the air to attract curious pronghorn within gunshot range. Flagging is now illegal, and protection of habitat and restrictions on hunting have allowed the pronghorn to recover a bit. Two pronghorn subspecies—the Sonoran pronghorn Antilocapra americana sonoriensis and peninsular pronghorn Antilocapra americana peninsularis—are endangered due to illegal hunting.

But help is on the way! There are now several measures being taken to help return the Sonoran and peninsular pronghorn to areas of restored natural habitat. The San Diego Zoo is participating as a supporting partner in such a program for the peninsular pronghorn in Baja California, Mexico.