Monday, October 01, 2012

Yellowstone's Pronghorn

I freely admit it - I call them antelope because I grew up with the song "Home on the Range."  But true antelopes are found in Africa.  The American antelope is really the pronghorn, Antilocapra americana. It is so truly unique it is the only member of the family Antelocapridae.  Their horns are unique.  Deer and elk have branched antlers that are shed each year.  Goats and cattle have hollow horns made from hair that are not shed.  Pronghorn have are the only animal with branched, hollow, hairlike horns that are shed annually.  Both males and females have horns, but male horns are larger and have a distinct prong.  Males also have a distinctive black marking on their face below the eye.

Running up to 60 miles per hour, it is the second fastest mammal in the world. It can sustain 30 miles per hour for miles. Only the cheetah is faster and the cheetah cannot sustain its speed as long as the pronghorn.

Pronghorns prosper in dry environments.  Pronghorn are found on the Great Plains from Texas north to North Dakota and in the high desert sage found in New Mexico, Arizona, Nevada, Utah, Colorado, Wyoming and Montana.  They eat forbs (non woody flowering plants) and sagebrush with grass making up only a very small portion of their diet.  In Yellowstone, they are frequently seen in the sagebrush in the Lamar Valley.

On our travels we have seen them regularly in northern New Mexico along highway 84/87 east of Raton, New Mexico and along I-25 in Northern New Mexico and southern Colorado. We've also seen them in other sage brush areas of Colorado.   They are common in the Texas Panhandle. I've seen them regularly near Vega and Borger.  They can also been seen in Texas near Alpine and Marfa.

Unlike deer, pronghorn do not jump fences. With the older style barbed wire fences, pronghorn literally run through them or go under the last wire.  Woven wire fencing is a true obstacle.

Pronghorn can raise the hair on their white rumps as a signal of danger.  This is a signal to the herd that danger is near.

The rut for pronghorn occurs in late summer and early fall.  Fawns are born in the spring, usually in pairs. They can walk within an hour of birth and by the fourth day can outrun a man. Pronghorn fawns are odorless as protection from predators such as coyotes and golden eagles. 

While not all pronghorn migrate, Wyoming pronghorns travel 150 miles between Wyoming's Upper Green River Basin and Grand Teton National Park.  They move away from areas with deep winter snow.  The only land mammal that migrates farther distances in North America is the caribou.  

These photographs came from Lamar Valley in Yellowstone.  We saw a small herd near the road. They were a mix of female and juveniles.   I saw the direction they were heading and chose to get ahead of them and park,  hoping they would stay near the road for some nice close up shots as they walked near the car.  I was most pleased when they did what I anticipated.