It once ranged the territory from eastern Kansas, western Iowa and Minnesota westward to the valleys of California and northern Mexico northward to southern Saskatchewan and Alberta. It is a typical animal of the plains and open rolling country—few animals are more fleet or wary than the pronghorn. Unfortunately their curiosity in regard to any object that they do not recognize or understand helped make them a fairly easy mark for the hunters. Many are the tales of the pronghorns being coaxed into gun range by their curiosity in a handkerchief or strip of bright cloth waving in the breeze.
The pronghorn is the only antelope in the world with branched or pronged horns and has the unique characteristic among all hollow-horned ruminants of shedding the outer covering of the horns annually. In the Yellowstone area this horny sheath sheds from the permanent bony core usually during November or December. The core is covered with a blackish skin, at first, then finally by the horny material that forms gradually downward from the tip.
Another characteristic of these animals is a conspicuous rump patch composed of white hairs, longer than any found elsewhere on the body. Through development of certain muscles it is possible for the animal to erect these white hairs until they stand out stiffly forming a dazzling white rosette. This is done in times of excitement and is usually considered a danger signal.
The tiny antelope kids are born in late May or June, usually twins but sometimes one or three. During the first several days after birth they remain carefully hidden in the grass but soon gain their strength and are able to keep up with their mother. It is interesting to note that antelope does occasionally seem to act as baby tenders for other does. Observers have reported upon a number of occasions seeing from four to six or seven kids following one doe without any other doe being visible in the immediate vicinity; or sometimes two does may be together with eight or ten young. The same practice has been observed with the bighorns.
Pronghorn
Enemies are principally coyotes, bobcats, and eagles in the case of the young.
General description: A little smaller than the average deer, with simple horns slightly curved and with one lateral prong. Horns present in both sexes though smaller or sometimes lacking in the female. Color reddish-brown or tan with darker brown to blackish mane, white rump and whitish or creamy underparts. Males about 54 inches in length, height at shoulder 34 to 36 inches and weight 100 to 125 pounds. Females smaller.
Terms: Male—buck; female—doe; young—kids.
Where found: Near Gardiner, between Gardiner and Mammoth, Swan Lake Flats, Mammoth to Tower Fall, along Yellowstone River below the Canyon and in the Lamar River valley and Slough Creek area. The park antelope population fluctuates over the years from a minimum of about 200 animals to a maximum of 800.