This common resident of the Great Plains and high deserts is endemic to North America and is the only living member of the family Antilocapridae. The closest relative to the pronghorn is the giraffe of Africa. The pronghorn is not an antelope, whose wild members are in the family Bovidae and occur in Africa and Eurasia. The ancestors of the pronghorn evolved in North America some 20 million years ago, eventually producing 12 or more different pronghorn species. The modern pronghorn has occurred in North America for at least 10,000 years, and is the only ancient large North American mammal to have survived the last ice age, when other members of the Antilocapridae family and other large mammals, such as sloths, camels, large cats, and mammoths went extinct.
The pronghorn is light brown or tan on the back and sides with a white belly, neck bands and rump. The horns are intermediate between true permanent horns like those of bison, which are never shed, and antlers of deer which are shed and regrown annually. The pronghorn has a permanent bony core with an outer sheath that is shed and regrown each year. Males have branching horns while the horns of females are very short and straight. Pronghorns eat a wide variety of vegetation, including forbs, grasses, shrubs, and cacti, and they are able to tolerate some plants that are toxic to domestic livestock. They are ruminants, with 4-chambered stomachs, like cattle, sheep, and deer, and they regurgitate food from a rumen pouch and chew the cud.
Pronghorns are well adapted for survival on the open plains, with the ability to run 35 mph for long distances and up to 55 mph for about half a mile. There is only one mammal that is a faster runner, the African cheetah. Pronghorns also have large eyes, as large as those of horses, which allow them to detect potential danger at great distances. The one or two fawns produced by a female in May or June rely on camouflage and hiding motionless in the grass for protection, though they can run faster than humans when less than a week old. Predators such as wolves, coyotes, and mountain lions are only able to take juveniles that they stalk and surprise, or old, sick or injured individuals. Padded cloven hooves provide sure footing on rocky ground. Though they are able to go without water for days, herds tend to stay within 3-4 miles of a water source.
While able to escape any predator by running, pronghorns are not great jumpers and may be stopped by fences, sometimes getting entangled in them. They often attempt to crawl under fences and the Arizona Antelope Foundation has initiated a campaign to replace the bottom barbed wire on fences with a smooth barbless wire. Fencing has disrupted the seasonal migrations of populations and led to mortalities from starvation and predation. Once numbering in the tens of millions, as abundant as historic bison populations, by the early 20th Century pronghorn numbers had been reduced to about 20,000. Conservation efforts have increased the species to some one million today.
Photos and video across fence taken near Hwy 41 south of Estancia, NM Nikon P900 camera. Free range photos taken at Wind Cave National Park, SD. Nikon P510 camera.
James Taulman is a semi-retired research wildlife biologist, having worked with the U.S. Forest Service research branch and taught zoology, ecology and other courses in several university positions. He is currently living in the East Mountains, and explores natural areas observing native wildlife and conducting independent research projects.