Pronghorn

Pronghorns get their name from the male's two pronged horns.

NPS Photo / Peelee Clark

 

Female pronghorns called does usually live together in small groups.

NPS Photo / Peelee Clark

One of the park's most unusual residents is the pronghorn “antelope”. Pronghorns are found in North America and nowhere else in the world. They have roamed the plains and deserts unchanged for over a million years. Some call them antelope because they resemble African antelope, although the two are not closely related. They are the only surviving member of their family, Antilocapridae. The pronghorn’s closest living relatives are the giraffe and okapi.

Although both males (bucks) and females (does) have horns, the female's are only tiny spikes compared to the male’s pronged horns that can grow up to 18 inches long. The horn is made up of two parts: a bony core and a black outer sheath. This sheath is made up of a stiff, hair-like substance. Pronghorns are the only animals in the world who shed their horn sheaths each year. The outer sheath of the horn falls off in the fall and will grow back by summer.

Pronghorns vary from light tan to a rich brown with white patches on the stomach, neck, and rump. When threatened, the hairs of the rump bristle, signaling to would-be predators that they have been spotted. This also signals to other pronghorns that there is danger nearby. Pronghorn bucks have black patches on the lower jaw below the eye and a black mask extending back from the nose. These markings make it easier to distinguish the male from the female. The pronghorn’s large eyes give them exceptional vision. They also have keen hearing and sense of smell.

 

Pronghorn fawns only see their mother for about 20 minutes each day.

NPS Photo / Peelee Clark

As the fastest North American land mammal, pronghorns can reach speeds up to 60 miles per hour for about half a mile. At top speed, they cover the ground in strides up to 24 feet and can run for longer distances at speeds of 30 to 40 miles per hour. There are no predators that can match their speed today, so it’s thought that they evolved to outrun the extinct American cheetah. Despite their speed, pronghorns cannot jump well and will dive under fences if they can’t get around them.

Pronghorns breed in the fall, and bucks fight each other to defend their territories. Bucks may have harems of three or more does. Fawns are born in late May or early June with twins being common. Newborns weigh about five pounds and lack the spots that are characteristic of elk calves and deer fawns. Fawns do not have an odor and instinctively lie motionless to hide from predators such as bobcats, eagles, and coyotes. Mother pronghorns hide fawns away from each other and leave their young for all but about 20 minutes each day. If you are lucky enough to see a fawn, it is most likely waiting for its mother, not abandoned.

Reintroduction

By the turn of the century, pronghorn numbers had plummeted due to overhunting and were absent from the Black Hills. In 1914, 13 pronghorns were reintroduced to the park from Alberta. In the early years, Wind Cave’s pronghorns struggled to survive, lacking enough space to outrun their predators due to the small size of the Wind Cave National Game Preserve. It wasn’t until the 1930s that their numbers began to increase significantly.