Pronghorn/Antelope
Antilocapra americana

Species description provided by eNature
Description
A medium-size, deer-like mammal with long legs. Upper body and outside of legs pale tan or reddish tan; chest, belly, inner legs, cheeks and lower jaw, sides, and rump patch are white. 2 broad white blazes across tan throat. Short erectile mane, about 2 3/4–4" (7–10 cm) long. Buck has broad black band from eyes down snout to black nose and black neck patch. Horns black: buck’s 12–20" (30–50 cm) long when fully grown; lyre-shaped, curving back and slightly inward near conical tips, each with 1 broad, short prong jutting forward and slightly upward, usually about halfway from base; doe’s horns seldom more than 3–4" (7.5–10 cm) long, usually without prongs. Juvenile grayer and paler than adult; acquires adult coloration at 3 weeks. Ht 35–41" (88–103 cm); L 4' 1"–4' 9" (1.25–1.45 m); T 2 3/8"–6 3/4" (6–17 cm); HF 15 3/8"–16 7/8" (39–43 cm); Wt male 90–140 lb (41–64 kg), female 75–105 lb (34–48 kg).

Endangered Status
The Sonoran Pronghorn, a subspecies of the Pronghorn, is on the US Endangered Species List. It is classified as endangered in Arizona. Once abundant in its range, the Pronghorn declined in numbers almost as precipitously as the American Bison. In 1913, owing to overhunting, the enmity of ranchers, and the fencing of rangeland, which hampered migration and foraging (Pronghorns cannot leap fences like deer—they crawl under them instead), there were only 500 Pronghorn left. Now, as a result of efforts at transplantation and management of herds by game departments, the Pronghorn’s range is expanding and its numbers have increased to more than a million. The Sonoran subspecies, however, remains rare, numbering only about 140 individuals in the US Conservationists suspect that the shrinking of its habitat, due to development and ranching, and poaching (mainly in Mexico) prevent its population from growing.

Similar Species
Cervids in its range are larger, lack large white rump patch, and have antlers rather than horns.

Breeding
Breeds September– October, earlier in the South; implantation delayed 1 month; after gestation of 7 months, 1 or 2 (rarely 3) young born May–June; birth weight 2 1/4–13 lb (1–6 kg).

Habitat
Grasslands; also grassy brushlands; and bunchgrass-sagebrush areas.

Range
Southeastern Oregon, s Idaho, s Alberta, s Saskatchewan, Montana, and w North Dakota south to Arizona and w Texas.

Discussion
The fastest animal in the Western Hemisphere and among the fastest in the world, the pronghorn, often making 20-foot (6 m) bounds, has been clocked at 70 mph (110 km/h) for three to four minutes at a time. Speeds of 45 mph (70 km/h) are not unusual, and the animal can maintain an easy cruising speed of 30 mph (50 km/h) for about 15 miles (25 km). The pronghorn runs with its mouth open, not from exhaustion but to gasp extra oxygen.

Active night and day, it alternates snatches of sleep with watchful feeding. Because it inhabits open terrain, it relies on spotting enemies at a distance and on its ability to flee speedily. The animal’s large, protruding eyes have a wide arc of vision and can detect movement 4 miles (6.5 km) away. If the pronghorn is alarmed, its rump hairs, which are about twice as long as other body hairs, become erect, almost doubling the size of the white rump rosette and producing a "flash" visible for great distances. When a herd flees, a buck usually serves as rear guard.

If the terrain, presence of young, or a surprise attack forces a pronghorn to fight rather than flee, it uses as weapons only its sharp hooves, which are effective enough to drive off a coyote.

The pronghorn avoids muddy ground but is a good swimmer.

In summer, it grazes on a number of plant species, including grasses, various forbs, and cacti, and drinks little water when moist green vegetation is available; in winter, it browses on many different plants, favoring sagebrush.

The pronghorn roams in scattered bands in summer, with does and fawns gathering in groups of a dozen or fewer; yearling and two-year-old males form bachelor herds of about the same size. Older males start establishing territories in March or April, and defend them through the end of the rut. Defense is much more vigorous in the center of a territory than on the periphery. Especially during the rut, males defend territories by staring down rivals, giving loud snorts, approaching and interacting with the intruders, chasing them away, and fighting if necessary, battling fiercely with their horns. Most breeding takes place on the most desirable territories. However, there is much variation in breeding systems in this species. A doe’s first breeding usually produces one fawn; subsequent breedings produce twins or, rarely, triplets. The doe spaces twins (or triplets) several hundred feet apart. Nearly odorless for their first few days of life, fawns lie quietly in high grass or brush while their mother grazes at some distance to avoid attracting predators. For about one week she returns frequently to nurse, and then does and fawns join the herd. About a month after breeding, horns are shed.

In winter, herds may include 100 animals or more, of both sexes and all ages. Migration from summer to winter range is variable, depending on altitude, latitude, and range conditions. Cold is no deterrent in itself, for the pronghorn’s coat keeps the animal warm even in severe weather; the air that fills the long, hollow outer hairs provides insulation, and the hairs flatten against the body to seal in warmth. (In summer, the animal molts to a thinner coat, and the hairs ruffle up to provide cooling ventilation.)

While a pronghorn can scratch through light snow for food, deep snow forces it to areas where browse is uncovered, including higher elevations where winds have swept away expanses of snow. The life span of the pronghorn is 7 to 10 years.