Equus hemionus onager
Physical Description: Persian onagers are a subspecies of Asiatic wild ass. Their stature and long ears are characteristic of asses. An onager’s coat is light beige or tan along the legs and belly, with darker beige or brown markings on their neck and sides, and a dark brown stripe along their back. They have a short brown mane that is two to three inches tall and stands up straight, like a zebra’s. Their tails are shorter than horses’ with only a small tuft of hair at the end.
Size: Onagers typically weigh between 440 and 575 pounds (200 – 260 kg) and stand approximately 50 inches (125 cm) at the shoulder.
Geographic Distribution: Today, only a few hundred Asiatic wild asses remain in the wild, isolated in two protected areas of Iran: Touran and Bahram-e-Goor. During the late Pleistocene, 40,000 years ago, Asiatic wild asses roamed as far as western Germany. Like many other large-bodied mammals, equids suffered a mass extinction about 12,000 years ago, which reduced their range, which has continued to shrink ever since.
Status: The biggest threats to Persian onagers are poaching for their meat and hide, habitat loss due to competition with domestic livestock for grazing lands, and drought. The Persian onager is extremely rare; the IUCN Red List of Threatened Species lists it as endangered. Scattered subpopulations are threatened because there is too little movement of animals between groups. Small groups of animals that don't get new members can develop hereditary problems, due to inbreeding. Today no more than 600 onagers remain in the wild. Approximately 30 individuals live in North American zoological institutions.
Habitat: Onagers live in a harsh semi-desert habitat, where summer temperatures can reach 120 degrees Fahrenheit (49 degrees Celsius)! In this sparse, hot land, they need to be creative to find enough food. They have adapted to life in the desert by staying near any water holes they find for as long as possible. They eat low-growing plants and grasses, and even the salty soil itself!
Diet: Onagers prefer to eat grasses when food is plentiful, but in the dry season, they also spend a great deal of time browsing on woody plants. Scientists have observed animals eating seedpods and breaking up woody vegetation with their hooves in order to extract the succulent portions at the base of the plant. They will dig holes up to two feet deep (60 cm) to obtain water in the dry season.
Reproduction: Scientists think the onager is a seasonal breeder, with most births occurring between April and September in North America. However, foals can be born at any time of the year. Female onagers reach sexual maturity when they are two years old and have a gestation length of approximately 11 months. Males are thought to reach sexual maturity at two but rarely breed before they are four years old.
Behavior: Territorial defense social systems seem to be the most common for onagers. A male guards a prime territory, and groups of females migrate between guarded territories, depending on their habitat and mate preferences. Some females remain in one guarded territory while others choose to move amongst several territories. Immature males sometimes form all-male groups before reaching breeding age. However, scientists have also observed onagers forming harem groups. In a harem-style social system, a dominant male guards a group of females from other males.