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Pronghorn (Antilocapra americana) Fact Sheet: Behavior & Ecology

Pronghorn (Antilocapra americana)

Activity Cycle

  • Diurnal; activity is greatest at dawn and dusk (Einarsen, 1948, Kitchen, 1974)
  • Sleep often, but for short periods without continuity or regularity
  • Spend the majority of their time feeding, resting, and ruminating
  • Activity schedule is highly variable, affected by season, weather, region, herd dynamics

Home Range

  • Daily area occupied by Wyoming Pronghorn was 2.6 to 5.2 sq km (1 to 2 sq mi) summer and autumn.

Social Groups

  • Social organization is influenced by differences in quality of habitat and density and spatial dispersion of individuals
  • Herd composition changes daily, even hourly; when food is plentiful, groups (bands) of 3 to 25 are spatially distant but still within visual contact of one another; in fall and winter, bands come together to form larger herd (as many as 1,000) as protection from predators
  • Dominance hierarchies are maintained by female bands, bachelor bands, and territorial male bands that contain more than one male (see Breeding Systems)

Communication

Visual Signs

  • Alarm: erect hair on white rump patch, doubling the size of the patch and producing a “flash” visible up to 2 miles
  • An aggressive male wishing to exaggerate the size of its horns will fold down the ears; the dark horns and dark facial markings will help emphasize the horns.

Vocalization

  • Warning: snort-wheeze
  • Male courtship: high-pitched whine
  • Rutting male: roar
  • Fawn: bleat

Olfaction

Territorial Behavior

  • Territorial males mark territory using a linked sniff-paw-urinate-defecate sequence
  • Each element of the sequence is performed in exaggerated form with extreme postural changes
  • Territorial males also mark tall grasses with secretions from cheek glands
  • Territorial challenge usually composed of five phases:
    • Stare at intruder
    • Advertise presence with snort-wheeze and erect the mane and hair of rump patch
    • Approach intruder, often trotting up to within 37 m (40 yards) then using stiff-legged gait to approach within 14 m (15 yards)
    • Broadside displays, walking parallel with head low
    • Chasing intruder out of territory, if he hasn’t already backed down
  • Fights with horns are rare, and usually take place in the presence of a female ready to breed. Such fights consist of a series of thrusts and counter thrusts with the horns, locking horns and twisting necks, and lunging at the opponent. Serious injury and death can result from stab wounds.

Locomotion

  • Usual running speed of 40 mph (64 km/h); maximum speed of 57 mph (92 km/h) for up to 9 miles (15 km)'
  • Leaping gait, with leaps covering 9 to 19 feet (3 to 6 m) at a time
  • Good swimmer
  • Instead of jumping over obstacles, prefers to go underneath them if possible

Bodies for Speed

 Pronghorn running

Pronghorn are the second fastest land mammal.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Byers (1997)
O'Gara (1990)
O’Gara & Yoakum (2004)

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