Pronghorn (Antilocapra americana) Fact Sheet: Physical Characteristics

Body measurements

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.

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.

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

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).

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 Wildlife Alliance. All rights reserved.

The pronghorn's distinctive white rump.

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

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

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