The Pronghorn eludes its enemies by fleetness of foot. It has been clocked at 95 km per hour for short distances and can cruise at 48 km per hour for for as much as 7 miles. Usually they do not jump over obstacles and, when barbed-wire fences block their path, they crawl or slide under the bottom strand, often very rapidly. When frightened the long white hair is raised on the rump patch and "flashes" in the sunlight. Even young fawns can race along with adults. During summer, pronghorns disperse, browsing and sunning in small loosely formed bands. Does form groups of up to a dozen; they usually wander away from the band to give birth, and then rejoin it a few weeks later with their fawns. Young bucks form slightly larger "bachelor" herds, and in good habitat adult males stake out territories which they defend all summer against other bucks. With the onset of the rut in late summer, territorial bucks try to "hold" does within the confines of their territories and, when females become receptive, mating occurs there. In poorer habitat, territories may not be defended. Non-territorial bucks also court does, often in groups, and the does often flee from this harassment to the territory of an older male. After the rut, males cast their horn sheaths, abandon their territories, and join other males, females, and fawns in large winter herds. Long movements (100 km or more) may take place at this time from summer to winter range. They shelter below cut banks and down in ravines to avoid cold winds. They are curious animals, and will flee to a ridge top when frightened, then pause and look back.
Adults may attain the following dimensions: total length 1245-1472 mm; tail 89-178 mm; hind foot 390-430 mm; ear 142-149 mm; weigh 47-70 kilograms.
Pronghorns in Kansas feed largely on forbs in late spring, summer, and early autumn, on forbs supplemented with dicots in late autumn and early spring, and on dicots in winter. The dicot most commonly eaten in areas that lack sagebrush is winter wheat. In fact, pronghorns are able to live and reproduce where 30% of the land is used for cultivated crops at least in part because they are able to use those crops as food during months when native foods are in short supply.
Healthy adult pronghorns can elude most predators, but coyotes routinely prey on newborn animals and sick or injured individuals.
Pronghorns are polygamous. Females typically become sexually mature at about 16 months of age, but some individuals conceive as early as 5 months of age. The breeding season in Kansas usually lasts through September. Gestation in captivity averages 252 days. Twins are more common than single young, being born in Late May or early June. New-born fawns weigh about 3 kg. They remain hidden for about 6 days, during which time the doe returns to nurse each twin. When they are about one week old, the fawns begin moving about with their mother. Frequency of nursing declines during summer, and the growing fawns eat more and more vegetation, until, with the onset of the breeding season in September, they are fully weaned.