Pronghorn
- CLASS: Mammalia (Mammals)
- ORDER: Artiodactyla
- FAMILY: Antilocapridae
- GENUS: Antilocapra
- SPECIES: americana
- SUBSPECIES: americana (Wyoming pronghorn), oregona (Oregon pronghorn), mexicana (Mexican pronghorn), peninsularis (Peninsular pronghorn), sonoriensis (Sonoran pronghorn)
ABOUT
One of a kind: The pronghorn is native to North America. It has no close relative on this—or any other—continent. It goes by many names: pronghorn antelope, prongbuck, and American antelope. The pronghorn is often called an antelope, and it does look like many antelopes. Yet it is different enough to warrant its own taxonomic family, Antilocapridae. Read on to learn more about this one-of-a-kind critter!
The horns of the pronghorn help make it unique: they are a cross between horns and antlers, with qualities of both. True antlers are made of bone and 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. Instead, the sheath is made of keratin but the horns shed yearly.
True horns have only one point, not the prongs or forks that antlers have. Yet the male (buck) pronghorn's horns can grow to be 10 inches (25 centimeters) long with a forward-facing prong. Hence its name: pronghorn. Female pronghorn (called does) also have horns, but they are much smaller. Pronghorn are the only animals in the world that have forked horns that shed each year!
A herd of sure-footed pronghorn dashing away looks like a group of cotton balls bouncing across their open, grassy, or desert habitat. Their tawny coats blend well with the dry landscape. That cotton-white rump patch serves as a beacon so the herd can stick together when fleeing. Their white underbelly and lower neck deflects heat rising from the ground. An outer layer of air-filled hairs helps them stay warm during winter. Come summer, they molt that coat and can erect their hair to stay cool.
Pronghorn have great adaptations for spotting and getting away from predators such as wolves, foxes, coyotes, bobcats, and golden eagles. Pronghorn have large eyes to help them see predators. Scent communication allows them to mark territories and warn others of danger. Pronghorn bucks have nine scent glands and does have six. Glands beneath the ears help to mark territory during breeding time.
Glands on the rump are 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.
If a predator does manage to sneak up on a pronghorn, the pronghorn’s amazing running skills come into action. Pronghorn can reach speeds of up to 53 miles (86 kilometers) per hour. This is not much slower than the fastest land mammal in the world, the cheetah. Yet the pronghorn can maintain high speeds much longer than the cheetah can. The pronghorn's hooves have two long, pointed toes cushioned to help take the shock when running at high speeds. Running with their mouth open allows pronghorn to take in lots of oxygen to fuel their running muscles. Although they are excellent runners, pronghorn are not good jumpers: if they come across a fence, they often go under it.
HABITAT AND DIET
Pronghorn are found in open prairie and desert habitats in western North America. Like many hoofed mammals, pronghorn spend their day—and night—eating and resting with their herd. As ruminants, they chew their cud while at rest. They rarely close their eyes to sleep, though, as they must remain alert for any potential danger. If they do sleep, it’s for less than 10 minutes at a time.
They are most active at dawn and dusk as they browse and graze on a variety of plants. They eat the non-woody flowering plants first, if available. Shrubs, grasses, cactus, and domestic crops are also on the menu, depending on the time of year. Shrubs are important in wintertime, and pronghorn use their front feet to dig for food buried in the snow. The pronghorn's teeth are always growing, because they wear down as they grind food. Pronghorns drink when water is available, but they can go for weeks without it, getting moisture from their food.
At the San Diego Zoo, our pronghorn get alfalfa pellets, hay, and fresh vegetation to eat.
FAMILY LIFE
During fall and winter, pronghorn live in large herds of up to 1,000 individuals. Each buck gathers three or four does in a small harem within the larger herd. Breeding takes place in September and October, with bucks defending and marking territories. Often, more dominant bucks have better territories with better food supplies to attract the does. Yet the females decide which males they want to breed with. They often stay with one male for a day or two before moving on to another to assess his fitness. Fawns born in the same litter often have different fathers.
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. 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. At four days old, they can outrun humans, and in one week, they are able to run faster than a horse, if needed. The mother keeps her fawn hidden in tall prairie grasses, coming back to nurse her baby every few hours, until it is about two weeks old. She then returns to the herd with her baby.
The young are weaned when they are about 12 weeks old. Does can become mothers at age two. Bucks can sire fawns at about age three, although they have to prove they are worthy to prospective mates!
Adult male pronghorn have a large, black gland on their jaw below the eye. They mark objects with these glands and even display the glands to prospective mates. Males also mark their area by pawing the ground to create a clear spot, urinating in that spot, and then pooping in the center of the spot.
Pronghorn alert others to danger by snorting and stamping. During breeding season, males may snort and chug or wheeze. At regular intervals they growl, roar, and smack their lips. Mother pronghorn use a quiet bleat to call their offspring, and the fawns (young) use a loud bleat if they are in danger.
CONSERVATION
No mammal, other than humans and perhaps the bison, has figured so prominently in the history of pioneer America as the pronghorn. They furnished some of the indigenous peoples of North America with meat and hides. Early travelers to America's West told of pronghorn herds dotting the plains as far as the eye could see. They were more numerous than bison. About 100 million pronghorn provided settlers with plenty of pronghorn steak. But as more people arrived in the West, pronghorn habitat and food declined. By 1920, there were only about 13,000 pronghorn left.
Part of this major decline was due to hunting. Early settlers tied handkerchiefs to poles and waved them in the air in a technique called flagging. This attracted 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.
Of the five pronghorn subspecies, the peninsular pronghorn Antilocapra americana peninsularis is at critical risk. Only 150 peninsular pronghorn remain in Baja California, Mexico. Hunting, agriculture, and cattle ranching (along with livestock fences) have led to the rapid decline of this subspecies.
But help is on the way! San Diego Zoo Wildlife Alliance participates as a supporting partner to reestablish the peninsular pronghorn in protected areas of Baja California. Breeding habitats, which are acres in size, allow translocated pronghorn to be monitored while having room to behave naturally. When they get reintroduced, the pronghorn are well prepared for life in their new home. An assurance herd of pronghorn lives at the Los Angeles Zoo, in case a natural disaster or disease wipes out the herds in their native habitat.
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