From Yellowstone Wildlife: A Watchers Guide
by Todd Wilkinson.
Pronghorn (Antilocapra americana) - are favorites among wildlife watchers in Yellowstone. Although traditional folk songs like "Home, Home on the Range" have immortalized them as "antelope," they are correctly identified as pronghorn. As relatives of such fleet African species as gazelles, pronghorn are the fastest animals to race across the plains of North America. Capable of reaching speeds of 70 miles per hour for miles at a time, they can also spring 20 feet in a single leap. Their latin genus, Antilocapra, mean santelop or "goat," indicating that they are remotely related to goats.
The population of pronghorn in the park has fluctuated widely, reaching an all-time high of perhaps 2,000 at the turn of the 19th century, approaching complete extirpation by the 1920s, and numbering about 500 today. In more ways than one, this marvelous population is unique. Because it is cut off from pronghorn breeding groups elsewhere in Montana, Yellowstone's pronghorn population exists on a sort of biological island.
Before settlement brought houses and barbed wire fences to the Yellowstone River drainage, nothing impeded the movement of pronghorn and bison along the river crear across to its confluence with the Missouri River in North Dakota. The animals that reside in north-central Yellowstone Park were merely an extension of countless numbers utilizing the riverside as a key transportation corridor.
When you examine these small, hooved quadrupeds, it becomes obvious why they are called pronghorn. They are handsome creatures whose symetrical, prong-like horns are strinking on males (bucks) and hardly noticeable on females (does). Their brownish markings, combined with a white-streaked underbelly, neck, and rump, make them easy to distinguish from other large mammals in the park.
To tell the sexes apart, look for horns longer than the ears and Black hair on the face and neck area of bucks, which are generally taller (about three feet at the shoulder) than female and weigh between 110 and 140 pounds. The horns of does, if you're able to spot them, are shorter than the ears.
The presence of pronghorn in such a small region of Yellowstone demonstrates the diversity of park habitat and the importance of specific niches. Preferring lower elevations and open, sagebrush-savanna, pronghorn occupy terrrain that is shared with deer and elk, particularly during the winter, when many animals gather on the northern rangeland to share abundant forage and plants.
As late spring and early summer approach, females begin disappearing from view, finding isolated coulees where they give birth to their young, often twins. A seasonal ocupation of both sexes is the shedding of a bark-like sheath from their horns. This occurs in late autumn, following breeding.
The prohibition on hunting in the park has helped propagate large bucks that would be coveted by hunters outside the Yellowstone boundary. Occasional forays into private lands and the adjacent national forest make pronghorn subject to hunting, but this involves only a small number of animals each year.
Bands of pronghorn typically congregate year-round at the north park entrance and along the seasonal gravel road running one way between Mammoth and Gardiner. Be on the alert for hikers and mountain bikers on the gravel road. The McMinn Bench area is quite productive for pronghorn watching, and the animals are often visible on the paved road between Yellowstone arch and the open meadows beyond the gate where you pay to enter the park. Continue to the next page, Trumpeter Swan.