Winters in the Gobi desert are usually long and very cold but the winter of 2009/2010 was particularly severe, a condition Mongolians refer to as “dzud”.

The International Union for Conservation of Nature said on Thursday that the Western Black Rhino of Africa has been declared officially extinct.

An endangered species of horse -- known as Przewalski's horse -- is much more distantly related to the domestic horse than researchers had previously hypothesized.

Wild asses are descendants of the original ancestors of the horse and the donkey, but unfortunately most species of wild ass are now in danger of extinction.

Of around seven land vertebrate species whose survival in the wild is threatened one is also kept in captivity.