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Monday, April 24, 2017

Species Fact Profile: Pronghorn (Antilocapra americana)

Antilocapra americana (Ord, 1815)

Range: Southern Canada, Western United States, Northern Mexico
Habitat: Grassland, Brushland, Desert
Diet: Forbs, Shrubs, Grasses, Cacti
Social Group: Large, loose groups of up to 1000 individuals (both sexes, all ages) in autumn and winter, breaking into smaller groups, segregated by sex, in spring and summer.  In wetter areas, males are territorial, with female groups passing through the territories of different males
Reproduction: Breeding from July through October.  Usually a female has a single fawn after her first pregnancy, twins after that.  Weaned at 4-5 months old, mature at 16 months
Lifespan: 10 Years
Conservation Status: IUCN Least Concern, CITES Appendix I

  • ·         Shoulder height 87 centimeters, head-tail length 128-150 centimeters, weight 47-70 kilograms.  Stock body supported on long, slim legs.  Males about 10% larger than females.  Northern pronghorn larger than southern
  • ·         Upperparts bred-brown to tan, underparts and rump are white.  Two white bands across neck.  Males have black patches on the face and side of the neck beneath the ears.  Northern pronghorn tend to be darker than southern pronghorn.  Hair is dense, filled with air to provide insulation, guard hails are hollow, overtop finer, shorter underfur
  • ·         Horns are unique that they are like antelope in consisting of a keratin sheath on a bony core, yet like deer in that they are forked and the outer sheath sheds annually.  Both sexes have horns, but those of the male are enlarged, with forward-facing prongs below backward-pointing hooks
  • ·         Fastest land mammal in the Americas, with speeds up to 86 kilometers per hour and capable of maintaining 70 kilometers per hour for several kilometers.  Speed likely evolved in response to now-extinct predators, such as American cheetahs.  Adaptations to bone structure make pronghorns excellent runners but poor jumpers; in their natural state there are few obstacles to jump over, but in a human-shaped landscape they have difficulty with fences
  • ·         Active both day and night, with peaks just before sunrise and after sunset.  Daily movements vary depending on seasons, travel more in winter
  • ·         Predators of fawns include coyotes, bobcats, and golden eagles.  Adults may be preyed upon by wolves and mountain lions.  Speed is main defense, but will also use horns and hooves.  When fleeing danger, will erect white fur on rump as a warning to others
  • ·         Only surviving member of the family Antilocapridae (means “Goat Antelope”).  Closet relatives uncertain, may be the giraffe and okapi.  First seen and described by 16th century Spanish explorers, not formally records until Lewis and Clark expedition
  • ·          Believed to have been 35 million before Europeans, reduced to 20,000 by 1920s due to hunting and habitat loss (fragmentation, fencing, competition with livestock); peninsular and Sonoran subspecies listed under US Endangered Species Act, recovery projects underway.  Legally hunted with permits in all western states.
  • ·         Feral population briefly existed in Hawaii in the late 20th century

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