Pronghorn

Description

Pronghorn are one of North America’s most impressive mammals. Not only do pronghorn have the longest land migration in the continental United States, they also are the fastest land animal in North America. Pronghorn can run at speeds close to 60 miles an hour. Although pronghorn are not as fast as cheetahs, they can maintain a fast speed for a longer period of time than cheetahs. Even more amazing than its speed is the pronghorn’s migration. Herds of pronghorn migrate 150 miles each way between Wyoming’s Upper Green River Basin and Grand Teton National Park. The only other land animal to travel farther in North America is the caribou.

Pronghorn are ungulates (hoofed animals) and related to goats and antelope. They have the body shape of a deer with long legs, short tail, and a long snout. The fur is a reddish-brown color, but it can also be tan or darker brown. Pronghorn have white stripes on their necks and additional white markings on the face, stomach, and rump. The rump has extra-long white hairs that the pronghorn can stick up when scared.

The most noticeable characteristic of pronghorn is also the source of their common name. Both males and females have a pair of short horns on the top of the head. The female’s horns are small, usually only a bump. In contrast, the males’ horns are around 10 to 12 inches long. They also have a unique shape, because unlike other ungulates, a pronghorn’s horns point backward. The horns extend straight up and then curve toward the rump. At the front of the horn is a small notch or prong that points forward, hence the animal's name.

Pronghorn have large eyes and fantastic vision. Their large eyes can spot predators from very far away, which is helpful on their flat grassland habitat. Pronghorn are about 4.5 feet long, three feet tall, and weigh between 90 and 150 pounds. Females tend to weigh less than the males.

Range

Pronghorn are found only in North America. Their natural range extended from southern Canada to northern Mexico. Today pronghorn are mainly found in the United States in the Great Plains, Wyoming, Montana, northeast California, southeast Oregon, Nevada, Utah, Colorado, Arizona, and New Mexico. Some of the highest numbers of pronghorn are in Wyoming in the Red Desert and Yellowstone ecosystems. Pronghorn like open plains, fields, grasslands, brush, deserts, and basins. Between the summer and winter, pronghorn migrate between feeding grounds to survive the harsh winter.

Diet

Pronghorn are herbivores. They eat grasses, forbs, sagebrush, and other prairie plants. Pronghorn digest their food twice. After they swallow food, it passes through the stomach and then the pronghorn regurgitates it. This process allows the pronghorn to break the plant material into smaller pieces so that more nutrients are absorbed. The regurgitated food is called cud. They seldom drink water because they receive most of their water from the plants they eat.

Behavior

Pronghorn depend on their strong vision to communicate. If a pronghorn spots a predator, it raises the white rump hairs. The white patch becomes larger and visible by other pronghorn. They know that the signal means to be on the alert—danger is near. Pronghorn also use smell to attract mates and signal danger.

Life History

Pronghorn breed in late summer or fall depending on their location—those in the southern part of the range tend to breed earlier. 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. Some pronghorn can be seriously injured during these battles.

Male pronghorn breed with multiple females within their territory. After mating, the females are pregnant throughout the winter and give birth in the spring. The females have either one or two fawns. Although fawns can stand within a day of birth, they are still weak for a few days and must be protected from predators. The fawns stay with their mother for about a year until they become independent. Pronghorn have an average lifespan of around 10 years.

The migration of pronghorn depends entirely on where the pronghorn lives. Some do not even need to migrate because the nearby land has plenty of food all year. On the other hand, several herds with about 400 pronghorn make a 300-mile roundtrip migration. In November, the snow starts falling in Wyoming and the local pronghorn herd knows that it will not be long before the snow gets too deep. In small herds, they start migrating south from Grand Teton National Park across government land, private lands, and ranches. For three days, the herd is on the move, and sometimes the pronghorn have to travel under fences and near roads. If they make it to the Upper Green River Valley, then the pronghorn will make the journey back north to greener pastures in April.

Conservation

Threats to pronghorn include habitat loss, human-wildlife conflicts, and overexploitation due to historic hunting, which greatly reduced the population size. Two subspecies of pronghorn are on the endangered species list: Peninsular pronghorn and Sonoran pronghorn.

The pronghorn's 300-mile migration is grueling and requires crossing private property and fences. In the past, pronghorn had to worry about predators and cold weather. Today the bigger threats are cars, impassable fences and roads, and development. The National Wildlife Federation and its affiliates are working hard to create wildlife corridors for pronghorn and other migratory wildlife and reduce conflicts between animals and people.

Fun Fact

Pronghorn are the second fastest land mammal in the world. (Cheetahs are the fastest.)

Sources

Animal Diversity Web, University of Michigan Museum of Zoology

National Parks Service

National Geographic

National Museum of Natural History

Smithsonian Magazine