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Pronghorns

The second fastest land mammal is the pronghorn (Antilocapra americana), a delicate artiodactyl which ranges across the western wilderness of North America from Canada to the Baja deserts.  Although they look similar to antelopes, pronghorns are actually the last surviving species of the family Antilocapridae. They can run at speeds of up to 60 miles per hour and (unlike impalas or cheetahs) they can run at full throttle for a fair distance.

The Range of the Pronghorn

Pronghorns are named for their forked horns—which are not antlers but true horns made of bone with a layer of keratin.  They shed the hollow outer sheaths each year in late autumn and grow a new pair over the winter. Adult pronghorns stand 90 cm (three feet) high at the shoulders and weigh up to 50 kg (110 pounds).  Although pronghorns can run swiftly, they are poor jumpers.  Herds of pronghorns make great migratory treks across the country and face pressure from human developments and from fences (which they can’t jump over but must run under).  If you are a rancher in pronghorn country you might consider putting a non-barbed strand of wire as the bottom wire on your fence.

 

Two Pronghorn Bucks

Pronghorns once had many close relatives.  The Antilocapridae family is most closely related to giraffes but the different family members filled many of the same niches that bovids do in the old world.  These animals came in an array of shapes and were widespread across North America. There were once 22 varieties of antilocapridae (which you can explore here) but they died out ten to fourteen thousand years ago when the Clovis hunters arrived and slaughtered North America’s megafauna.

The distinctive head of Osbornoceros

Sick or injured pronghorns are sometimes preyed upon by wolves, coyotes, or cougars, but when they are healthy, adult pronghorns can easily outrun all contemporary North American predators. Their blazing speed is not an evolutionary extravagance: pronghorns once needed their swiftness to escape Miracinonyx trumani, the American cheetah which could probably run nearly as quickly as the living African cheetahs.  Like the avocado the pronghorn was molded to fit an ecosystem which has died out: today they are literally running from ghosts.

An American Cheetah Hunting a Pronghorrn

 

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