Pronghorn Antelope

Pronghorn Antelope

Pronghorn Antelope

Description: Pronghorn antelope are only found in North America. They are often referred to as “antelope,” however, they are not closely related to any African antelope species. The scientific name originates from Antilo=antelope andcapra=goat, thus antelope-goat. There are five subspecies of pronghorn, three of which occur in Arizona. They are the American pronghorn (A. a. americana), Sonoran pronghorn (A. a. sonoriensis), and Chihuahuan pronghorn (A. a. mexicana).

The name “pronghorn” is derived from a forward projection or prong on each horn. Pronghorn have true horns, in that the horn sheath is composed of fused hairs which cover a bone core. The horn sheath is shed each year in October-November. In comparison, deer and elk have antlers which are composed entirely of bone and shed completely each year. Both sexes of pronghorn have horns, but those of the female are much smaller (4 inches), seldom exceeding the length of the ear. Horns on males reach their maximum length, 12-20 inches, by the beginning of breeding season, July or August.

Pronghorn are not large animals when compared to deer or elk. Mature males, called bucks, stand 36-40 inches at the shoulder and weigh 85-130 pounds. Females, or does, weigh 75-105 pounds. Pronghorn have chunky bodies with long, slim legs. Relative to body size, they have a large windpipe, heart, and lungs which allows them to take in large amounts of air when running. These features combined with an extremely light bone structure, contribute to the pronghorn’s amazing speed. Pronghorn can maintain speeds of 40 mph for several miles, reaching 60 mph in shorter bursts.

Pronghorn are striking in appearance, with a tan body and sharply contrasting white markings on the head and neck. The belly and lower sides are creamy white and the short tail is surrounded by a large white rump patch. Unlike does, a buck’s nose is dark, brownish-black and he has a triangular black patch on each cheek. Pronghorn eyes are unusually large, about 2 inches in diameter, and are set well out on the sides of the head. This allows a wide field of vision. Biologists believe pronghorn vision is roughly equal to looking through eight-power binoculars. Whether or not this is true, they usually see you before you see them.

Pronghorn hair is very brittle and is shed throughout the year. During extreme weather conditions, the hollow hair provides excellent insulation. Pronghorn hair is also used as an alarm signal. By erecting the white rump hair, a pronghorn alerts the herd of possible danger.

Habitat: Open grass and forest parks.

Food Preferences:

Grasses, weeds, cacti, juniper, winterfat, and chamiso. Pronghorn are selective, opportunistic foragers. They feed on forbs, shrubs, grasses, and sometimes cacti and domestic crops. Forbs make up the largest part of their diet, followed by shrubs, then grasses. Forbs are typically eaten from spring to late fall and are critical to good fawn production. Shrubs are eaten all year, but are most important in winter when forbs are not readily available. Grasses, though relatively unimportant, are eaten when young and succulent. Other food types vary locally in importance. Recently disturbed ground, such as burned areas, are often good foraging sites because they can provide an abundance of new plant growth.

Habits:

Pronghorn are chiefly diurnal, most active in mornings and evenings, but may be seen moving at any time. Pronghorn are nomadic with seasonal movements often occurring over large areas. Movements are often dependent upon the quality and quantity of habitat and vary widely among individuals. Pronghorn tend to winter in large herds, with animals of both sexes feeding and bedding close together. However, in mild winters bucks and does may remain separated. During spring, pregnant does isolate themselves to give birth. By late-spring, doe-fawn groups have formed. Bachelor herds of young, non-territorial bucks are also common. Mature bucks are solitary at this time, often defending a territory or harem of does. The most aggressive bucks do most of the breeding.

Pronghorn are curious, but do not hesitate to place plenty of distance between themselves and possible danger. When in flight, bucks normally run with their noses pointed toward the ground while does tend to hold their heads high. Does generally lead the herd with a buck bringing up the rear. At long range, these behavioral characteristics help distinguish between sexes.

Breeding notes: Normal breeding period is August – September, average number of young – 2.

Predators or Enemies:

Coyotes, bobcats, mountain lions, golden eagles, and wild dogs prey on pronghorn. Coyotes are the primary predator of fawns in Arizona. Pronghorn losses due to predation vary with pronghorn and predator numbers, habitat type, and availability of alternative food sources for predators. Speed and exceptional eyesight are the pronghorn’s best protection from predators. A fawn’s best defense from predators is to choose good bedsite cover and to lie motionless.

Size Individual Range: 20-40 square miles

Distribution:

1,000-8,000 feet in the grasslands of northern and southern Arizona. Pronghorn are less widely distributed today than in the mid-1800′s when numbers probably reached the tens of millions. Under pristine conditions, pronghorn ranged west of the Mississippi River from southwestern Canada through the Rocky Mountain region south to central Mexico. By the 1920′s, pronghorn numbers reached a low of about 30,000 with only about 650 in Arizona. Possible factors leading to the drastic decline in pronghorn may have been subsistence and market hunting, and disease introduced by livestock.

Today, approximately 10,000 American pronghorn are found in Arizona, chiefly in the north-central portion of the state. Small, scattered herds of Chihuahuan pronghorn occur in southeastern Arizona and the endangered Sonoran pronghorn are found in southwestern Arizona. Most of Arizona’s pronghorn population is found between 3,000-7000 feet elevation. Sometimes, northern herds occur as high as 10,000 feet during summer. Sonoran pronghorn occupy areas below 1000 feet elevation. This range in elevation encompasses a variety of grassland habitats ranging from desert grasslands to forest and mountain meadow. Pronghorn prefer flat, open grassland areas, but also use rolling or broken hills and mesa tops of less than 20 percent slope. They also use such diverse habitats as sparse deserts, woodlands, and open forests.

Live Weight: Male – 110 lbs.; Female – 75 lbs.

Pronghorn Antelope Viewing Locations

Look for pronghorn antelope at the following locations: