Many animal species inhabit Thailand’s forests. Elephants, traditionally used as beasts of burden, are raised in captivity but also live in the wild. Other large animals native to Thailand include the rhinoceros, tiger, leopard, gaur (wild ox), water buffalo, and gibbon. Thailand has more than 50 species of snakes, including several poisonous varieties. Crocodiles are numerous, as are fish and birds. Other animals, such as the Schomburgk’s deer of the central plain, have already become extinct.