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approaching danger. The white hair stands out vividly against the antelope's drab environment and signals the alarm. There seem to be sentinels within the herd that stand guard when the group feeds or rests, much like other herd or flock-type animals.
A major portion of the pronghorn's's diet is composed of forbs and browse plants, but normally little grass.
A study in Kansas indicates cacti made up 40 percent of the antelope's diet, forbs 36, grasses 22 and browse two percent.
In Nebraska where browse species are lacking on the antelope's range, pronghorns utilize winter wheat and alfalfa.
Wise range managers encourage pronghorns to use their rangeland to discourage the increase of undesirable plant species. Pronghorns also consume poisonous and injurious plants, including larkspur, loco weeds, rubber weed, rayless goldenrod, cockleburs, needle-and-thread grass, yucca, snakeweed, Russian thistle and saltbush.
During late summer and early fall, the bucks begin to challenge imaginary rivals, or two or more bucks may engage in mock battles, but injuries seldom occur. As the height of courtship and mating approaches in September and October, females in the harem become more and more attentive to the bucks.
Pronghorns have been known to breed as fawns but they usually breed for the first time when they are 16 to 17 months of age. The does usually produces twin fawns in early June after a gestation period of about 250 days.
Fawn production has been as high as 105 fawns per 100 does in one unit, but a 1991 survey in the Panhandle indicated a ratio of 59 fawns per 100 does.
Fawns are usually born in swales and low-lying areas with small ridges or hills surrounding them where the vegetation is short and sparse. At birth a fawn weighs between five and nine pounds.
The greatest losses occur during the first two months of life. Only about 40 percent of the fawns born in June live until mid-July. In Nebraska most of the 60 percent loss of fawns is due to coyote predation. Coyote control can improve fawn survival, but it is not economically practical on a large scale. In a few areas bobcats are important predators and in areas close to bluffs golden eagles kill and feed on fawns.
Adult mortality probably averages about 10 percent annually, but exceptional circumstances such as the severe winter of 1978-79 can be devastating.
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