Pronghorn

During the Pleistocene epoch, about 11 other antilocaprid species existed in North America, many with long or spectacularly-twisted horns.^[8] Three other genera (Capromeryx,^[9][10] Stockoceros^[11][12] and Tetrameryx^[13]) existed when humans entered North America but are now extinct.


The pronghorn's closest living relatives are the giraffe and okapi.^[14] The Antilocaprids are part of the infraorder Pecora, making them distant relatives of deer, bovids, and moschids.


The pronghorn is the fastest land mammal in the Americas, with running speeds of up to 88.5 km/h (55 mph). It is the symbol of the American Society of Mammalogists.^[15]

Etymology[edit]

The animal gets its name from its horn sheaths that branch and have a forward-pointing tine, unlike the horns of species from the ox family Bovidae.^[16]

Pronghorns form mixed-sex herds in the winter. In early spring, the herds break up, with young males forming bachelor groups, females forming harems, and adult males living solitarily.^[28] Some female bands share the same summer range, and bachelor male bands form between spring and fall. Females form dominance hierarchies with few circular relationships.^[42] Dominant females aggressively displace other females from feeding sites.


Adult males either defend a fixed territory that females may enter, or defend a harem of females. A pronghorn may change mating strategies depending on environmental or demographic conditions.^[28]: 228 Where precipitation is high, adult males tend to be territorial and maintain their territories with scent marking, vocalizing, and challenging intruders.^[43] In these systems, territorial males have access to better resources than bachelor males.^[43] Females also employ different mating strategies. "Sampling" females visit several males and remain with each for a short time before switching to the next male at an increasing rate as estrous approaches. "Inciting" females behave as samplers until estrous, and then incite conflicts between males, watching and then mating with the winners.^[44] Before fighting, males try to intimidate each other. If intimidation fails, they lock horns and try to injure each other.^[16] "Quiet" females remain with a single male in an isolated area throughout estrous.^[44] Females continue this mating behavior for two to three weeks.^[16]


When courting an estrous female, a male pronghorn approaches her while softly vocalizing^[45][28] and waving his head side to side, displaying his cheek patches.^[46] The scent glands on the pronghorn are on either side of the jaw, between the hooves, and on the rump.^[16] A receptive female remains motionless, sniffs his scent gland, and then allows the male to mount her.^[28]


Pronghorns have a gestation period of 7–8 months, which is longer than is typical for North American ungulates. They breed in mid-September, and the doe carries her fawn until late May. The gestation period is around six weeks longer than that of the white-tailed deer. Females usually bear within a few days of each other.^[20] Twin fawns are common.^[29] Newborn pronghorns weigh 2–4 kg (4–9 lb), most commonly 3 kg (7 lb). In their first 21–26 days, fawns spend time hiding in vegetation.^[43] Fawns interact with their mothers for 20–25 minutes a day; this continues even when the fawn joins a nursery.^[43] The females nurse, groom, and lead their young to food and water, as well as keep predators away from them.^[43] Females usually nurse the young about three times a day.^[20] Males are weaned 2–3 weeks earlier than females.^[43] Sexual maturity is reached at 15 to 16 months, though males rarely breed until three years old. Their lifespan is typically up to 10 years, rarely 15 years.^[20][16][21]