Kouprey (Bos sauveli also known as Kouproh or Grey ox) is a wild forest-dwelling ox found mainly in northern Cambodia but also believed to exist in southern Laos, western Vietnam, and eastern Thailand. It was discovered in 1937.
Kouprey is a very large ungulate, about the same size as a Wild Asian Water Buffalo. Male Kouprey stand up to two metres tall at the shoulder and weigh an average of 900 kilograms. However, the kouprey herds recently discovered in Vietnam have individuals attaining weights of about 1700 kg or so, according to Vietnamese zoologists. Kouprey have tall but narrow bodies, long legs and humped backs. Kouprey can be either grey, dark brown or black. The horns of the female are lyre-shaped with antelope-like upward spirals. The horns of the male are wide and arch forward and upward, and they begin to fray at the tips at about three years of age. Both sexes have notched nostrils and long tails.
Kouprey live in low, partially forested hills where they eat mainly grasses. Kouprey are diurnal, eating in the open at night and under the forest cover during the day. They live in herds of up to twenty, generally consisting of only cows and calves, but also bulls during the dry season.
There are estimated to be fewer than 250 kouprey left in the world. These low numbers are attributed to uncontrolled hunting by locals and soldiers, in conjunction with diseases introduced from cattle and loss of habitat. However the kouprey is suspected to have always been somewhat rare.
Research published by Northwestern University in London's Journal of Zoology indicated that a comparison of mitochondrial sequences showed the Kouprey might be a hybrid between a Zebu and a Banteng. However, the authors of this study have rescinded their conclusion, and because a fossilized skull was found dating from the late Pleistocene or early Holocene epoch, they concluded that the kouprey is not a hybrid. More recent genetic analysis has demonstrated that the kouprey is not a hybrid.
There is a possibility that a second, smaller species of kouprey exists.