Przewalski's Horse (Equus przewalskii or E. caballus przewalskii), also known as the Mongolian Wild Horse, or Takhi, is the closest living relative of the Domestic Horse and may in fact be the same species. (Authorities differ about the correct classification.) The two are the only equids that can cross-breed and produce fertile offspring.
The current (as of 2002) world population of these horses is about 1000, all descended from approximately 15 captured around 1900 and bred in zoos. The wild population in Mongolia died out in the 1960s; captive-bred horses were returned to the wild starting in 1992. The area to which they have been reintroduced became Hustai National Park in 1998.
Przewalski's Horse is stockily built by comparison with domesticated horses, with shorter legs. Typical length is about 2.1 metres with a 90cm tail; weight is around 350 kilos. The coat varies from dark brown around the mane (which stands erect) to pale brown on the flanks and yellowish-white on the belly.
In the wild, Przewalski's Horses live in social groups consisting of a dominant male, several mares, and their offspring. Each group has a well-defined home range; within the range, the herd travels between three and six miles a day, spending time grazing, drinking, using salt licks, dozing, and taking mud baths. At night, the herd clusters and sleeps for about four hours.
Fillies leave their natal groups around age 2, and look for a herd to join, after which they will begin to breed. Colts are driven out when they are about three years old, and spend a year or two in small bachelor herds, practicing fighting. At around age 5, a stallion will either try to take over an existing herd; steal one or more mares from another stallion's harem; or gather unattached fillies.
General Nikolaï Mikhaïlovitch Prjevalski (1839-1888) was a Russian explorer and naturalist.