|[Note Guidelines] Photographer's Note|
|The Pronghorn (Antilocapra americana) is a species of artiodactyl mammal indigenous to interior western and central North America. Though not an antelope, it is often known colloquially in North America as the American antelope, prong buck, pronghorn antelope, or simply antelope because it closely resembles the true antelopes of the Old World and fills a similar ecological niche due to parallel evolution. |
It is the only surviving member of the family Antilocapridae.
As a member of the superfamily Giraffoidea, the pronghorn's closest living relatives are the giraffes and okapi. The Giraffoidea are in turn members of the infraorder Pecora, making pronghorns more distant relatives of the Cervidae (deer) and Bovidae (cattle, goats, sheep, and antelopes), among others.
Pronghorns have distinct white fur on their rumps, sides, breasts, bellies, and across their throats. Adult males are 1.3–1.5 m long from nose to tail, stand 81–104 cm high at the shoulder, and weigh 40–65 kg. The females are the same height as males, but weigh 34–48 kg. The feet have two hooves, with no dewclaws. Their body temperature is 38 °C.
Each "horn" of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core. As in the Giraffidae, skin covers the bony cores, but in the pronghorn, it develops into a keratinous sheath which is shed and regrown on an annual basis. Unlike the horns of the family Bovidae, the horn sheaths of the pronghorn are branched, each sheath possessing a forward-pointing tine (hence the name pronghorn). Males have a horn sheath about 12.5–43 cm (average 25 cm (9.8 in)) long with a prong. Females have smaller horns that range from 2.5–15.2 cm (average 12 centimetres) and sometimes barely visible; they are straight and very rarely pronged. Males are further differentiated from females in having a small patch of black hair at the angle of the mandible. Pronghorns have a distinct, musky odor. Males mark territory with a preorbital scent gland which is located on the sides of the head. They also have very large eyes with a 320° field of vision. Unlike deer, pronghorns possess agallbladder.
The Pronghorn is the fastest land mammal in the Western Hemisphere, being built for maximum predator evasion through running. The top speed is very hard to measure accurately and varies between individuals; it can run 35 mph for 4 mi (56 km/h for 6 km), 42 mph for 1 mi (67 km/h for 1.6 km), and 55 mph for 0.5 mi (88.5 km/h for 0.8 km). It is often cited as the second-fastest land animal, second only to the cheetah. It can, however, sustain high speeds longer than cheetahs.
Range and ecology
Pronghorns prefer open, expansive terrain at elevations varying between 900 and 1,800 m , with the densest populations in areas receiving around 25–40 cm of rainfall per year. They eat a wide variety of plant foods, often including plants unpalatable or toxic to domestic livestock (sheep and cattle), though they also compete with them for food.
Cougars, wolves, coyotes, and bobcats are their major predators. Golden eagles have been reported to prey on fawns and adults.
Social behavior and reproduction
Pronghorns form mixed-sex herds in the winter. In early spring, the herds break up, with young males forming bachelor groups, females forming their groups, and adult males living solitarily. 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. 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. Where precipitation is high, adult males tend to be territorial and maintain their territories with scent marking, vocalizing, and challenging intruders. In these systems, territorial males have access to better resources than bachelor males. 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 oestrus approaches. "Inciting" females behave as samplers until oestrus and then incite conflicts between males, watching and then mating with the winners. Before fighting, males try to intimidate each other. If intimidation fails, they lock horns and try to injure each other. "Quiet" females remain with a single male in an isolated area throughout oestrus. Females continue this mating behavior for two to three weeks.
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. This gestation period is around six weeks longer than that of the White-tailed Deer. Females usually bear within a few days of each other. Twin fawns are common. Newborn pronghorns weigh 2–4 kg, most commonly 3 kg. In their first 21–26 days, fawns spend time hiding in vegetation.
Population and conservation
The protection of habitat and hunting restrictions have allowed pronghorn numbers to recover to an estimated population between 500,000 and 1,000,000 (excluding the Sonoran Pronghorn, which is down to about 200). Some recent decline has occurred in a few localized populations, due to bluetongue disease, which is spread from sheep, but the overall trend has been positive since conservation measures were put in place.
Pronghorn migration corridors are threatened by habitat fragmentation and the blocking of traditional routes.
Pronghorns are now quite numerous, and outnumbered people in Wyoming and parts of northern Colorado until just recently. They are legally hunted in western states for purposes of population control and food.
Source: Parts of Wikipedia
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