The pronghorn is one of the most often seen animals on the prairies from Alberta and Saskatchewan through the western states to Baja California and western Sonora, Mexico.

Mistakenly called an antelope, the tan and white goat-sized animals with the distinctive white rump patch unfortunately are viewed with only mild interest by the majority of passing motorists.

They are missing the point. This is no ordinary animal. It is so special in so many ways you should stop, get out the binoculars and take a good look when you can.

One reason they're so special is they are only found in North America.

For evolutionists, the pronghorn is the sole surviving member of the family Antilocapridae that evolved during the Miocene Epoch 23.8 million years ago.

Although biologists named it Antilocapra Americana which means "American antelope-goat," it is not an antelope like the African oryx or impala, nor is it a goat. In fact, scientists believe it might be a distant relative of the deer family.

Writer Joe Eaton said the pronghorn evolved in the North American savannas during the Miocene Epoch. He writes the remains of a dwarf spike-horned relative called Capromeryx has been found in the tar pits at Rancho La Brea.

But unlike true antelope or other animals with horns or antlers, pronghorn shed and regrow their outer keratin horn sheaths each year, retaining only the bony core.

Their bodies are the size of a goat's, but their eyes are almost as large as an elephant's and are located far back on the head. Being equivalent to eight-power binoculars, they have almost 360-degree peripheral vision and are able to spy moving objects up to three or four miles away without lifting their head while grazing.

If they sense danger, they have a unique "smoke signal" capability. Out on the plains where herds are spread out, it's impossible to vocalize if a predator approaches. But pronghorn have the ability to flare the white hairs on their rumps, which is like flashing a mirror in the sun and alerts all the other pronghorn in the area.

Once alerted, their true uniqueness kicks in. These are the second-fastest land mammals on earth.

The pronghorn can attain speeds between 50 and 60 mph for short sprints, but unlike the faster cheetah, which would be winded after a couple hundred yards, the pronghorn can drop into a comfortable jog of 30 to 45 mph for four or five miles.

They usually produce twins and will drop the young 50 to 100 feet apart to better hide them on the open plains.

After two or three days, fawns not only can walk but could outrun a man if needed. After a couple of weeks, they can reach speeds of up to 35 mph.

They are preyed on by coyotes, cougars, bobcats and golden eagles, but aside from hunters their biggest predator are fences. Pronghorn don't jump fences.

If it's a three-strand barbed wire, they will get down on their knees and wiggle under. But if it's a four-strand lower than 16-inches high or a woven-wire fence, it is a death trap for migrating pronghorn.

Looking back

National Geographic.com states one of the first recorded mentions of pronghorn is found in the expedition journals of Meriwether Lewis and William Clark.

Sept. 14, 1804: "In my walk I Killed a Buck Goat (antelope) of this Countrey, about the hight of the Grown Deer, its body Shorter . . . he is more like the Antilope or Gazella of Africa than any other Species of Goat."

Because Easterners never before had seen pronghorn, what few skins were collected were stuffed and sent to Washington, bones and all.

According to the U.S. Fish and Wildlife Service, pronghorn populations declined from an estimated 30 million to 60 million in the early 1800s to less than 15,000 by 1915.

It took a moratorium on hunting and federal tax dollars to create habitat to nurse the numbers back; today there are an estimated 1 million pronghorn on the plains.

In Colorado, the number dropped to about 2,000 at the turn of the 20th century but has returned to about 55,000, according to state Division of Wildlife biologist Mark Vieira.

Pronghorn don't compete very much with cattle.

"Cattle and bison have big mouths and they can take in all sorts of plant material, some nutritious, some not, but they get enough of what they need to do well," Vieira said.

"Pronghorn have small mouths, and they are far more selective in what they eat."

Vieira said in the northeastern portion of the state, pronghorn mostly eat forbs and grasses. Forbs are broad-leaved flowering plants that many people consider weeds. Pronghorn can digest noxious plants that would be more dangerous to cattle such as larkspur, yucca and locoweed.

The southeastern portion offers more forbs, while in the northwestern corner near Craig, they are drawn to shrubs, sage and bitterbrush. While they don't migrate 20 or 30 miles from high to low country and back like deer and elk do, pronghorns migrate two to three miles along a vertical plane.

"In summer, you'll see them spread out, with bachelor bucks in one area, does with fawns in another - although they usually are pretty much in sight of one another," Vieira said.

"Come August, during the rut, they come together, and by winter they herd up and you can have more than 100 animals in one area."

There has been quite a problem, at least in the northeastern plains, in the past few years because of the drought.

"On the Pawnee National Grasslands north of Greeley and east of Interstate 25, our usual fawn production was 50 to 60 fawns per 100 does," Vieira said.

"Now it's fallen to 18 per 100."

Mostly it's a lack of good vegetation for females that either causes them to lose their fawns before birth, or they don't produce milk with adequate nutrition to keep fawns alive.

It's not only a matter of starving, but they don't manufacture the antibodies needed to ward off disease.

There is fear among state wildlife biologists that they might have lost an entire age class by now.

"We are really desperate for moisture now," Vieira said. "If we could get two good years, we could bring the population back."



gerhardtg@RockyMountainNews.com or 303-892-5202

Back to Top