Kingdom: Animalia
    Phylum: Chordata
        Class: Mammalia
             Order: Artiodactyla
                Suborder:
                    Family: Antilocapridae
                        Subfamily: Antilocaprinae
                            Genus: Antilocapra
                                  Species: Antilocapra americana
                                        Subspecies: A. a. americana, A. a. mexicana, A. a. sonoriensis, A. a. peninsularis

Genetics

•  Historical: South-central Canada, south to the high plains north of Mexico City, and from the Mississippi River and Gulf Coast of Texas west to the Pacific Ocean.
• Current: Southeastern Oregon, southern Idaho, southern Alberta and Saskatchewan, Montana, and western North Dakota south to Arizona, western Texas, and northern Mexico
• Distribution has been reduced and fragmented by human development, especially fenced rangelands and ranches, which prevent pronghorn seasonal migration and foraging; illegal hunting has reduced populations in Mexico.

• 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

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

•   Physical 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.

• 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

• 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)

• Male pronghorn utilize different breeding systems within the same population, influenced by resources, population density, and sex ratio. (Maher, 2000)
  • Territorial: When resources vary in quality or are clumped in defined locations, breeding males compete for the best territories (containing water and succulent vegetation) then defend a band of females within that territory
  • Dominance: When resources are more uniform, bands with females and multiple males form; the males maintain a dominance hierarchy among them and the most dominant male conducts most of the breeding
  • Harems: When resources are widely dispersed, population levels are low, or the sex ratio is skewed (1 male to 10 or more females), individual males defend a harem without regard to a defined territory

• 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

• Females direct mate choice, using three strategies:
  • Sampling: females visit several harem-holding males, staying with each a few days before switching, usually returning to a male they visited within a week of estrus for mating
  • Inciting: use sampling behavior until estrus, then run away from the male, inciting chasing and aggressive displays and fights among competing males. Female watches competition and mates with the winner
  • Quiet: a month before estrus, female moves to an isolated, peripheral location occupied by a single male and stays with him throughout estrus and mating
• Breeding sequence:
  • Male approaches female with a high-pitched whine
  • Receptive female raises her tail and stands
  • Male approaches waving his head from side to side in a pronounced gesture, making low sucking sounds, then mounts
  • Copulation is brief, one forceful pelvic thrust
• Females may be harassed by bachelor males, with increasing aggression as estrus approaches; they often seek refuge with a territorial male, which chases off the bachelor

• Sexual maturity: females – 16 to 17 months; males – 1 year, although most will not breed until they are 3 to 4 years old and can compete to defend a territory or harem
• Breeding season:
  • Northern populations: mid to late September, three-week rut is typical
  • Southern populations: September to October, although breeding behavior is seen as early as July
  • Synchronous birthing, most fawns born within a 10-day period

• Age at weaning: 4 to 5 months

• Reach full weight by 4.5 years, females reach this faster than males

• Sexual maturity for males by one year, but at this age they don't usually have an opportunity to breed.
• Females are sexually mature around 16 months, but have been known to conceive at 5 months.

• 7 to 10 years

In the wild

• Bluetongue virus, a.k.a. catarrhal fever
  • Caused by Orbivirus serotype 17 and transmitted by insect vectors, particularly Culicoides sp.
  • Occurrence in eastern Wyoming in 1976 killed at least 3,200 pronghorns; occurrence in northeastern Wyoming in 1984 resulted in 300 known deaths (Thorne et al. 1988)
  • Virus transmission occurs during warm summer months and subsides with onset of cooler weather
• Parelaphostrongylus tenuis (Simmons et al. 2002)
  • Parasitic nematode that infects the brain of many ungulates, resulting in severe neurological damage leading to death
  • White-tailed deer are hosts, unaffected by the nematode but pass it on to other species through feces
  • Gastropods act as intermediate host – crawl over the white-tailed deer feces and become infected with the larvae of the nematode; ungulate consumes vegetation and inadvertently ingests the gastropod

In captivity

• Fusobacterium necrophorum has been contracted by wild-caught pronghorns brought into captivity and housed in close proximity with domestic bovid species
  • Infection causes pododermatitis and/or stomatitis that can lead to septicemia and death
  • Has occurred sporadically in the wild as well, in conditions where wild ruminants have been crowded within an area
  • Wet pastures, warm temperatures, and presence of cattle feces increases chances of infection (Edwards et al. 2001)

• At one time there were thought to be 35 million or more pronghorns in their original range. During the latter half of the 19th century, numbers were reduced by 99% due to hunting and loss of habitat to agriculture, settlement, and fencing tracts of land, falling to 13,000 by 1915
• Conservation practices ended the decline in the early 20th century. From 1915 to 1925, the population increased to 30,500
• The population continued to increase into the 1980s, reaching more than 1 million in 1984, the highest number in the 20th century
• By 1997, the population had decreased again by about one-third
• In 2000, population estimates were 32,000 for Canada, 1,200 for Mexico, and 765,200 for the United States, a combined total of 799,200
• The Mexican subspecies (mexicana, peninsularis, and sonoriensis) experienced a continual decline of more than 80% throughout the 20th century
• Fewer than 300 Sonoran Pronghorn in the U.S. and 200-500 individuals in Sonora, Mexico. (IUCN 2008)
  • Populations of Sonoran Pronghorn in Arizona and Mexico protected since 1967 under US Endangered Species Act.
  • In 1998 US Fish and Wildlife Service developed a recovery plan for Sonoran Pronghorn.

• With one exception, U.S. populations of Pronghorn (Antilocapra americana) are now excluded from CITES control.(http://www.cites.org/eng/resources/species.html) (2009)
• CITES I status for a small Arizona and Mexico population of Pronghorn (Antilocapra americana)
  • This designation includes traditional subspecies A. a. sonoriensis.
• CITES I status for Mexican populations of Pronghorn (Antilocapra americana)
  • This designation includes traditional subspecies A. a. peninsularis and A. a. mexicana
• IUCN least concern, Ver. 3.1 for Pronghorn (Antilocapra americana) (http://www.iucnredlist.org/details/1677)
• US Fish and Wildlife Service: Antilocapra americana peninsularis and A. a. sonoriensis: Endangered (2009) http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A04M
  • First listed in 1975.

• Habitat loss from agriculture urban and mining expansion
• Removal of native vegetation by rangeland projects
• Fencing across seasonal movement routes
• Heavy livestock grazing
• Hunting

•  IUCN Antelope Specialist Group (these scientists monitor American Pronghorn status , even though taxonomically Pronghorn are not antelope) (http://www.itis.gov/servlet/SingleRpt/RefRpt?search_type=source&search_id=source_id&search_id_value=225)

Return to the Fact Sheets page