Pronghorn (Antilocapra americana): Facts, Speed and Horns

What does a pronghorn look like?

The pronghorn is slender and long-legged, with a tan to reddish-brown back and white underparts. Two broad white bands cross the throat, and the white of the belly runs up the sides and around a large white rump patch. Males have a black mask on the face and a black patch on each side of the neck, behind the jaw.

The eyes are very large and set high on the side of the head, giving a field of view of about 320 degrees. That lets a pronghorn spot danger across the open plains from far away. Unlike deer, pronghorns have no dewclaws, only two hoofed toes on each foot, cushioned underneath to absorb the shock of running.

The coat is made of hollow hairs that trap air, insulating the animal against winter temperatures far below freezing. In the summer heat, a pronghorn can raise its hairs to let air reach the skin and release heat.

How big is a pronghorn?

Pronghorns are about the size of a large goat or small deer. Adults stand about 81–104 cm (32–41 in) tall at the shoulder and measure about 1.3–1.5 m (4.3–4.9 ft) from nose to tail. Males weigh about 40–65 kg (88–143 lb), and females are about the same height but lighter, at 34–48 kg (75–106 lb).

Pronghorn horns: the only shed horn sheaths

The animal’s name comes from the male’s horns, which curve back at the tip and have a short forward-pointing prong partway up. Each horn has a permanent core of bone covered by a black sheath of keratin, the same material as fingernails. Every year, between about late October and December after the breeding season, males shed the outer sheaths, and new ones grow back over the cores by the next summer.

This combination is unique. Deer shed their entire antlers, which are made of bone. Cattle, goats, sheep and antelopes keep their horns for life. The pronghorn sits in between, shedding only the sheath. Females often have small horns too, usually just a few centimeters long and rarely pronged. The details are covered in Is a pronghorn an antelope?

How fast is a pronghorn?

The pronghorn is built for speed and stamina. It is credited with bursts of about 88 km/h (55 mph) and can run at about 56 km/h (35 mph) for several kilometers. A cheetah would win a short sprint, but no other land animal is known to sustain such speeds for so long.

The secrets are an unusually large windpipe, heart and lungs for its body size, a high red blood cell count, light bones and long, efficient strides. These figures come mostly from people timing running pronghorns alongside vehicles, so they are estimates. Read more in How fast is a pronghorn? or compare it with other record holders in our list of fastest animals.

Why is it so fast when no living North American predator can match it? A well-known idea links its speed to extinct predators such as the “American cheetah,” Miracinonyx. More recent fossil studies suggest pronghorn ancestors were already fast before such predators appeared, so the question is still debated.

Where do pronghorns live?

Pronghorns live only in western and central North America. Their range runs from southern Alberta and Saskatchewan in Canada through the Great Plains and the intermountain West of the United States into northern Mexico, including Sonora and the Baja California peninsula. They have disappeared from parts of their former range, such as Iowa, Minnesota and Manitoba.

They prefer wide, open country where they can see predators coming: shortgrass and mixed-grass prairie, sagebrush steppe, shrubland and desert, mostly at about 900–1,800 m (3,000–5,900 ft) above sea level. Wyoming holds the largest numbers, and pronghorns are easy to spot in places such as the Lamar Valley, part of the animals of Yellowstone.

What do pronghorns eat?

Pronghorns are herbivores that browse and graze. They eat mostly forbs (broad-leaved flowering plants), shrubs such as sagebrush and saltbush, grasses, and in dry regions cacti. Sagebrush is especially important in winter, when other plants are buried by snow.

Like cattle and deer, pronghorns are ruminants that chew the cud. They eat many plants that cattle avoid or find poisonous, so the two do not compete as much as might be expected. They get much of their water from juicy plants, but most herds stay within a few kilometers of water.

Behavior, herds and migration

Pronghorns form large mixed herds in winter, sometimes of hundreds of animals. In spring the herds break up: females gather in small groups, young males form bachelor groups, and mature males hold territories or follow groups of females. When alarmed, a pronghorn flares its white rump hairs, a signal other pronghorns can see from far away, and releases a strong scent from glands in the rump.

Some populations make long seasonal migrations between summer and winter ranges. The “Path of the Pronghorn” between Grand Teton National Park and the Upper Green River Basin in Wyoming, which some animals travel for well over 150 km (90 mi) each way, became the first federally designated wildlife migration corridor in the United States in 2008. Fences, highways and energy development are among the biggest obstacles on such routes.

Reproduction and life cycle

The breeding season, or rut, takes place in about mid-September to early October. Males defend territories or groups of females, display their cheek patches and make loud snorts, and sometimes fight with their horns. Females may visit several males before choosing a mate.

Pregnancy lasts about 250 days, unusually long for a North American hoofed animal of this size. Fawns are born from about late May to June, and twins are common. Each fawn weighs about 2–4 kg (4–9 lb) and spends its first three weeks or so lying hidden in vegetation while its mother feeds nearby. Fawns can run within days of birth, but for their first weeks they rely mainly on lying still and hidden. Females can breed at about 16 months, while males rarely breed before about three years old.

Predators, threats and conservation

Most fawns are killed in their first weeks, mainly by coyotes, bobcats and golden eagles. Adults are hard to catch and are taken mainly by cougars, wolves and coyotes, often in deep snow. Severe winters can also kill many pronghorns.

Overhunting and habitat loss reduced pronghorns to perhaps around 13,000 animals by the 1920s. Protection, refuges and careful management brought a strong recovery, and today there are thought to be roughly 500,000 to 1,000,000. The IUCN lists the species as Least Concern. Two subspecies are much rarer: the Sonoran pronghorn of Arizona and Sonora, listed as endangered under the U.S. Endangered Species Act, and the peninsular pronghorn of Baja California, which survives in small numbers.

Modern threats include fences that block movement, highways, housing and energy development that cut migration routes, and drought. Wildlife crossings over highways in Wyoming have helped pronghorns and mule deer move safely.

Pronghorn myths and facts

Myth: the pronghorn is an antelope. It looks and behaves much like the gazelles of Africa, but it belongs to a separate family found only in North America. “Pronghorn antelope” is a common nickname, not a scientific grouping.

Myth: pronghorns shed their horns like deer shed antlers. Deer drop their whole bony antlers each year. Pronghorns keep the bony core of each horn and shed only the black outer sheath, which is unique among living animals.

Myth: only males have horns. Many females also grow horns, though they are short, usually just a few centimeters, and rarely have a prong. Some are so small they are hidden in the hair.

Fact: pronghorns are poor jumpers for their athletic build. They can leap over a ditch or a low bush while running, but they almost never jump over fences, preferring to slip underneath. A smooth bottom wire set about 45 cm (18 in) above the ground is a common recommendation for pronghorn-friendly fencing.

Fact: pronghorns are survivors of the Ice Age. They shared the plains with mammoths, camels, horses and lions in North America, and they are one of the few large native mammals of that era that are still common today.

The last of its family

The pronghorn is the only surviving species of the family Antilocapridae. During the Ice Ages, several other pronghorn relatives lived in North America, some with four horns or spiraled horns, but they all died out. Its closest living relatives are thought to be the giraffe and the okapi, not the antelopes of Africa and Asia that it so closely resembles.

The pronghorn was described for science in 1815 by George Ord, after Lewis and Clark’s expedition encountered it in 1804 and called it a “goat” or “antelope.” It is the symbol of the American Society of Mammalogists.