The pronghorn, or American antelope, can
sprint sixty miles per hour and run at forty
miles per hour. Pronghorns are fast almost from
birth. For example, two-day-old pronghorns can
outrun humans. Pronghorns are the only living
members of the artiodactyl sub-family Antilocapridae,
related to antelope. They are not true
antelope and reportedly are almost unchanged
from ancestors of two million years ago.
Pronghorns inhabit open grasslands in plains
and semideserts and depend on keen eyesight to
detect enemies (wolves and coyotes) and on speed
to escape them.Whenpronghorns are afraid, their
white rump hairs rise and are visible for miles. An
endangered pronghorn also emits warning odors
from rump scent glands. This gives other pronghorns
time to seek safety.
Pronghorns are ruminant herbivores. In the
summer they eat herbs, sagebrush, and grasses.
During winter, pronghorns dig under the snow
for hidden grass and woody plant twigs. When
water is scarce, they get needed moisture by eating
cacti. Pronghorns are sociable creatures, and
their groupings reflect living conditions. In summer,
males form single-sex groups, and females
live with offspring. In winter, pronghorns form
large herds containing both genders.
Physical Characteristics of Pronghorns
Pronghorns are graceful, tan to reddish-brown animals, with solid, chunky bodies, strong but slender legs, and short tails. Their bellies, rump patches, and throat bars are very white. Male pronghorns (bucks) grow to body lengths of 4.5 feet, shoulder heights of 3.5 feet, and weights of 155 pounds. Bucks have back-curving horns with prongs, which is the source of the species name. The horns are up to 1.5 feet long and made of a bone core over which a black horny covering grows. The covering is shed and renewed every year, and horn core is retained. Females have much smaller horns and also shed the coverings. Pronghorns are the only known animals that shed horn covers. Pronghorns are artiodactyl herbivores (others include cattle, pigs, goats, deer, and antelope), which walk on two toes. Their ancestors had five toes, but evolution removed the first toe, and the second and fifth toes are vestigial. The support toes—the third and fourth toes—each end in a hoof. Many artiodactyls are ruminants that chew and swallow vegetation, which enters the stomach for partial digestion, is regurgitated, chewed again, and reenters the stomach for more digestion. Bovids, including pronghorns, have true horns (called horns henceforth). They are permanent, hard, pointy skull outgrowths that usually occur only on heads of males. Horns of females, where present, are smaller. All have bone cores, and atop the core is a tough skin layer rich in keratin, a durable covering for underlying bone. In pronghorns, horn coverings are shed and regrownevery year, allowing horns to enlarge.
The Life Cycle of Pronghorns
In the spring, pronghorn herds separate according to age and gender. Does live in small herds and bucks live in breeding territories that they mark with scent from glands under their ears. Each buck tries to attract mates and scare away rivals by bellows or charges. Sometimes very violent battles arise over territories. In August and September, does begin to pass through individual male territories. Some stop and mate with a buck; others move to the next breeding territory. Gestation lasts eight months and usually produces twin offspring (fawns). Fawns weigh 7 to 8.5 pounds at birth. They develop quickly and are weaned in five months. Pronghorns live about ten years in the wild and up to fourteen years in captivity When North America was settled by Europeans, over fifty million pronghorns lived on the continent. In the early twentieth century, it was estimated that their population was only twenty thousand to twenty-five thousand, due largely to indiscriminate hunting. At that time pronghorns were protected by severely limiting their hunting. This control and careful wildlife management have raised the pronghorn population to 500,000. Wyoming, Montana, andNewMexico permit limited hunting of pronghorns.
Genus and species: Antilocapra americana
Geographical location: Throughout North America
Habitat: Open grasslands in plains and semideserts
Gestational period: Eight months
Life span: Ten years in the wild, up to fourteen years in captivity
Special anatomy: Back-curving, pronged bone horns over which a black horny covering grows; the covering is shed and renewed every year, and the core is retained
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