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Pronghorn (Antilocapra americana) Fact Sheet: Physical Characteristics

Pronghorn (Antilocapra americana)

Physical Characteristics

Body measurements

Attribute Males Females
Weight 42-59 kg (93-130 lb) 40-50 kg (88-110 lb)
Length
133.8-149.4 cm (52.7-58.8 in)
128.3-148.6 cm (50.5-58.5 in)
Tail Length 8.3-13.5 cm (3.3-5.3 in) 8.6-12.7 cm (3.4-5 in)

 

Data on body measurements from Tables 20 and 22 in Chapter 5 of O'Gara and Yoakum (2004). Values reported are means from study populations across western North America.

General Appearance

Coloration and Patterns

  • Upper body and outside of legs light tan or reddish tan; chest, belly, inner legs, cheeks, lower jaw, sides, and rump patch are white
  • Two broad white blazes across the throat. Male has broad black band from eyes down the snout and a black neck patch
  • Rump patch is a large circular patch of white hairs 7 to 10 cm (2.8 to 4 inches) long, which can be erected as a signal
  • Long black eyelashes help protect the eyes from the sun.

Horns

  • Having forked or branching horns is a distinguishing feature of the Antilocaprid family. (Davis 2007)
  • Both sexes carry horns. About 70% of females have horns, which may be stunted or undeveloped
    • Females may have horns with no sheath
  • Male horns 30 to 50 cm (11.8 to 19.7 inches); female horns, if present, seldom more than 7.5 to 10 cm (3.0 to 3.9 inches)
  • Developed by three years of age
  • Black and composed of a permanent, bony interior knob covered by a keratinous sheath, which is shed annually like antlers
  • Lyre shaped, curving back and slightly inward near conical tips, each with one broad, short prong that juts forward and slightly upward, usually halfway from the base
  • Used in male competitions during the rut, using thrusts and counter thrusts to try to gore opponents
    • Prongs used to catch the thrust of opponent's horn and also to deliver serious piercing stabs.

Mane

  • Short hairs that stand on end, about 7 to 10 cm (2.8 to 3.9 inches) long
  • Reduced or absent in mexicana subspecies

Vision

  • Large, protruding eyes that appear to be located on the side of the head but are oriented forward enough to allow limited binocular vision
  • Largest eyes of any North American ungulate in relation to its size; each eyeball is about 36 mm (1.4 inches) in diameter
  • Nearly a 300-degree arc of vision without moving head or eyes; can detect movement up to 6.5 km (4 miles) away
  • See movement more clearly than stationary objects

Feet

  • Pointed double hooves, with cartilaginous padding to cushion shock in running over hard ground and rocks
  • Front hooves are larger than back ones and carry most of the weight while animal is running
  • Females strike with front hooves during agonistic encounters
  • Both sexes have glands on the feet that secrete an oily conditioner for the hoofs.

Sexual Dimorphism

  • Males average 10 percent larger than females
  • Males have longer horns
  • Black face and neck markings are not present in females

Other Physical and Physiological Characteristics

Adaptations for long-distance running and endurance

  • Long limbs with reduced number of toes
  • Lightweight bones
  • Small digestive tract to use less energy during locomotion
  • Large tracheae, lungs, heart for rapid intake of oxygen and increased rate and power of circulation.

Genetic characteristics

  • Variable number of chromosomes; the diploid number is 58 or 60 (Wurster and Benirschke, 1968; O’Gara & Yoakum 2004).
  • Antilocapridae shows genetic similarities to both Bovidae and Cervidae.
    • Studies showed the chromosome number and configurations in pronghorn similar to bovids (Todd 1975; Baccus et al 1983)
    • Baccus et al. (1983) maintained that the pronghorn is genetically similar to cervids.
  • DNA investigations indicate Antilocapridae is a legitimate family of its own (Cronin et. al, 1996).
  • Occasional specimens have extra horns or teats, females may or may not have horns, and some females have a different type of uterus than others (O’Gara, 1968).

What's in a Name?

Pronghorn face

Pronghorn have forked or branching horns, with a forward-pointing tine, setting them apart from antelopes and bovids (cattle, sheep, buffalo, etc.).

The only suriviving member of Antilocapridae, they are unique in the animal world.

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

A White Sight

the white rump of an American Pronghorn

The pronghorn's distinctive white rump.

This female has small horns compared to the male pictured above.

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

Page Citations

Byers (1997)
O'Gara (1978)
O’Gara & Yoakum (2004)

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