Pronghorn

## Description

The pronghornAntilocapra americana) is a species of artiodactyl (even-toed, hoofed) mammal found in western and central North America. Though not an antelope, it is known colloquially in North America as the American antelope, Prong buck, Speed goat, Pronghorn antelope, Prairie antelope, or simply antelope because it closely resembles the antelopes of the Old World and fills a similar ecological niche due to parallel evolution. It is the only surviving member of the family Antilocapridae.

## Appearance

The pronghorn is tan to reddish-brown in color. Its cheeks, belly, chest, rump, and the insides of its legs are white. Males have a wide black mask running from their eyes to their noses, black parches on their necks, and pronged black horns. The horns of the male are shaped like a lyre, curving in towards each other. Females don’t have black markings, and the horns are generally straight short spikes. The pronghorn possesses horns, not antlers, and is the only animal with branched horns and the only animal that each year sheds its horns. The outer sheath falls off in the autumn and grows back every summer.

## Distribution

The pronghorn is native to North America and is distributed throughout the treeless deserts, plains, and basins of western North America, across the southern prairie provinces in Canada, south into the west of the United States, and to the north of Mexico. Pronghorns are typically found in grassland, chaparral, sage scrub, and desert. The southern part of their range consists mostly of open prairies and arid grasslands.

## Behavior

This highly-strung animal is active day and night, alternating snatches of sleep with focused feeding. Pronghorns are opportunistic and selective foragers. The timing, length, and seasonal movement patterns vary regionally. Pronghorns come together in mixed-gender herds in winter. The herds break up in early spring and young males form bachelor groups, females join a group of females, and adult males live on their own. Females form dominance hierarchies which include circular relationships. Dominant females will aggressively displace other females at feeding sites. Pronghorns travel up to 160 km away from winter ranges to get away from very deep snow.

## Diet

Pronghorns are herbivorous (folivorous) animals. In summer, they graze on grasses, cactus, and forbs, while in winter, they eat sagebrush and other plants that are available.

## Reproduction

Pronghorns are polygamous. Late in summer or in early fall, a male gathers his harem of three or four does. Pronghorns are usually ready to breed at 16 to 17 months. Breeding takes place from mid-September until October. Horns are shed one month after breeding. Females usually produce twins, following a gestation of about 250 days. After birth, for several days the fawns are weak and cannot keep up with the adults, so mothers and the young rest near the water until they are strong enough. Females care for their fawns from birth until 1 to 1.5 years, until they are independent. Males do not help with raising offspring. Reproductive maturity is reached at 15 to 16 months, though males rarely breed until 3 years old.

## Population

### Threats

Today, there are some localized declines taking place, especially to the Sonoran Pronghorn, mostly as a result of livestock grazing, new roads, and fences, and other barriers to historical habitat, insufficient food and water, illegal hunting (especially in Mexico), and lack of recruitment.

### Number

According to the IUCN Red List, the total pronghorn population size is around 1 million individuals. Specific populations of this species have been estimated in such areas: fewer than 300 individuals of Sonoran pronghorn in the United States; 200-500 individuals in Mexico; around 200 Peninsular pronghorn in and around breeding centers in Baja California. Overall, currently, pronghorns are classified as Least Concern (LC) and their numbers today remain stable.

### Ecological niche

Throughout their range, these animals live alongside cattle, sheep, bison, and horses. Pronghorns improve rangeland quality for other species through eating invasive plants and noxious weeds. Introduced livestock may overgraze in areas shared with pronghorn, reducing cover and the amount of food. Reduction of cover may cause more deaths amongst the young through predation.