Pronghorn

Quick Take

• The pronghorn is North America's fastest land mammal, but its speed alone isn't why scientists think it evolved to run that fast. See their running behavior →
• DNA testing has just upended where the pronghorn actually belongs on the animal family tree, and the answer will surprise you. Explore the family tree debate →
• A pronghorn's eyes are its most underrated feature, something that becomes clear when you learn what they can detect from miles away. Discover their remarkable eyes →
• Pronghorn populations once crashed to a jaw-dropping low, and the story of what pulled them back reveals just how fragile their recovery still is. See population history →

Pronghorns are the only remaining members of the Antilocapridae family. They can run up to 55 to 60 miles per hour, making them the fastest North American land mammal. The hair shaft on pronghorns is hollow, which keeps them insulated in freezing climates. Pronghorns usually give birth to one or two babies, called fawns, who can outrun humans when they are just two days old. When Lewis and Clark first wrote about this animal, it was estimated that there were about 3.5 million, but that number has been reduced to 800,000, which is still better than the 13,000 believed to have been alive in 1915.

5 Incredible Pronghorn Facts

• Pronghorns are the second fastest land mammal in the world behind the cheetah.
• Pronghorns have hollow hair shafts, which help insulate them in the cold.
• A pronghorn baby, called a fawn, usually weighs between 7 and 9 pounds when it is born.
• Both bucks and does have horns, but bucks have longer ones.
• Of the five subspecies of pronghorns, the peninsular pronghorn that lives in the Vizcaíno Desert of Baja is the rarest.

Classification and Scientific Name

The scientific name of the pronghorn is Antilocapra americana. The word Antilocapra combines the roots for antelope and goat, giving it the overall meaning of ‘antelope-goat.’ Some scientists do not believe that pronghorns should be in their own family. Some argue that they should be classified as members of the Bovidae family, which includes bison, African buffalo, water buffalo, and antelopes. Others say that they should be classified as members of the Cervidae family, including members of the deer family. Recent DNA testing indicates that they are closely related to members of the Giraffidae family, which includes giraffes and okapis.

Appearance

Pronghorns weigh between 90 and 130 pounds, with very few bucks reaching 150 pounds. Females weigh about 10% less than bucks. Bucks are usually between 52.7 and 58.8 inches long, while does are between 50.5 and 58.5 inches long. The tail on both sexes is between 3.5 and 5.5 inches long.

The upper body and outer part of the pronghorn’s legs are light-to-reddish tan. This animal has white on its chest, stomach, inner legs, cheeks, lower jaw, and sides. It also has a large circular white patch on its rump. While most of the white blends in very well with the rest of the body, this animal’s two white blazes across its throat stand out prominently. Bucks also have a black band from their eyes to their snouts and a black neck patch. This animal looks like it is wearing artificial eyelashes because its lashes are absolutely black and very long.

Pronghorns may not develop horns and sheaths until they are 3 years old. About 70% of does have horns that can be up to 3.9 inches long. Alternatively, bucks have horns that can be up to 20 inches long. These lyre-shaped horns curve slightly backward, and they are branched. Each horn has one small tip that points straight upward while the rest of the horn points towards the animal’s back. The horns have a bony interior and a keratinous sheath. Uniquely among horned animals, the outer keratinous sheath is shed annually after mating season, while the bony horn core remains permanent.

The hair shafts on the pronghorn are hollow. Additionally, this animal has a short mane. The hairs on the mane are between 2.8 and 3.9 inches long and may stand straight up.

The pronghorn has enormous eyes that are capable of seeing movement up to 4 miles away. The eyes allow the animal to see almost a 300-degree view without moving its head. Each of the eyes is nearly 1.4 inches in diameter, which is the largest of any North American hooved mammal compared to its size.

Pronghorns have pointed double hooves. Each hoof has cartilage in the middle. The front hooves are larger than the back hooves.

Behavior

Pronghorns are diurnal animals that are most active at sunrise and sunset. If you watch a herd of pronghorns, you will see that they are restless animals. They frequently rotate between eating, sleeping, and ruminating, but do not spend extended amounts of time doing any activity.

These animals live in herds. When grass and other feeds are plentiful, the herds often contain about 35 animals. While the herds are dispersed, they are often in visual contact with each other. During the winter and other times when food is scarce, up to 1,000 animals live in a herd. Pronghorns usually cover up to 2 square miles each day when food is plentiful.

Usually, herds contain all females or all bachelors. When pronghorns become sexually active, they form a territorial herd, but there is generally more than one buck in these herds.

Pronghorns communicate with their hair and their voices. When they sense danger, the hair on their rumps stands up, which expands the circumference of the large circle. Then, other pronghorns can see it up to 2 miles away and know that they need to be alert. Short warning wheezes usually accompany this flash.

Bucks that want to show superiority to another buck or want a doe to think they are impressive will lay their ears back, making their horns look bigger. The buck will also emit a high-pitched whine when trying to impress a female. When a male is rutting, it will emit a roaring sound.

Males mark their territory, although they seldom fight over it unless there is a doe in heat nearby. They rub their cheeks against tall grasses to leave their scent. Bucks also mark their territory while using exaggerated motions. First, they sniff and paw the ground. Then, they urinate before finally defecating.

If a buck senses that another buck is challenging its territory, it will stare at the challenger. Then, it will wheeze while showing off its mane and rump patch. Next, it will trot up to within 40 yards of the intruder before hanging its head low and walking parallel to the intruder for a short distance. If the intruder is still present, it will finally run at it and keep running after it until it has left the area.

Babies call to their mothers by bleating. You may actually think there is a sheep nearby.

Pronghorns are great runners that can keep running up to 9 miles without stopping. They usually run at about 40 miles per hour, but they can achieve speeds up to 60 miles per hour. They use a leaping gait and can clear up to 19 feet in a single bound. They are great runners, but they are not good jumpers. Therefore, they prefer to go under an obstacle when possible. They rely on their eyesight to spot danger far away and give themselves a chance at survival.

Habitat

Pronghorns prefer to live on shrublands, but they will live in steppes when necessary. Each of the five different subspecies of pronghorns has a slightly different habitat.

American and Oregon pronghorns are the largest subspecies, and they live in Wyoming and Oregon. Scientists say that this group has the biggest chance of survival. Sonoran pronghorn live in Arizona’s Sonora Desert. Peninsular pronghorns may be extinct in California and now live only on a small peninsula below Baja, California. The final subspecies is the Mexican pronghorn, and they live in Northern Mexico, where their numbers are threatened by overhunting. Reducing hunting pressure is essential to give pronghorns a chance of survival in Mexico.

Diet

Pronghorns are herbivores. The different places that they live determine the exact foods that they eat.

Those living in a desert environment, such as the Sonoran and Mexican subspecies, eat desert plants. When food is plentiful, they drink very little water. once their food sources dry up during the hot summer months, they rely on chain fruit cholla for both food and water.

American and Oregon pronghorns are more opportunistic eaters who dine on rabbitbrush, sagebrush, bitterbrush, bunchgrass, bluegrass, bottlebrush, ricegrass, squirreltail, and cactus. Grass makes up about 12% of their diet.

Regardless of where they live, pronghorns are light diners. Thirty-eight pronghorns can live on the same amount of food needed by one cow, and 43.5 pronghorns consume the same amount of grass as one sheep.

Predators and Threats

The main natural predators of pronghorns — wolves, cougars, bears, and even eagles — all prey upon pronghorn. The animal that eats the most pronghorns in Wyoming is the coyote.

Man is the main threat to pronghorns. Many herds of pronghorn have gone extinct because of overhunting. This continues to be a problem, especially in Northern Mexico. Additionally, the erection of fences and the building of roads divide their territory, making it harder for animals to get together to breed.

Reproduction and Life Cycle

Males reach sexual maturity at 12 months, but most will not breed until they are 24 months old. Females reach maturity at 16 months. Bucks go through a 3-week rutting period. In the northern part of their geographical area, this normally happens in September and later in the southern part.

Gestation lasts between 245 and 255 days. Most fawns in a herd are born within about 10 days of each other. They will weigh between 7 and 9 pounds. After the first pregnancy, most pronghorns give birth to twins.

Most pronghorns live to be 8 to 10 years old. They are weaned at about five months and will not reach their full weight for about 5 years.

Population

There are approximately 750,000 pronghorns left in the wild, and they are classified as Least Concern. While the population remains strong in Wyoming, that is not the case in the rest of their territory. As their territory becomes more fragmented, the total number continues to decline.