Père David's deer
Conversely, many artiodactyls have declined significantly in numbers, and some have even gone extinct, largely due to over-hunting, and, more recently, habitat destruction. Extinct species include several gazelles, the aurochs, the Malagasy hippopotamus, the bluebuck, and Schomburgk's deer. Two species, the Scimitar-horned oryx and Père David's deer, are extinct in the wild. Fourteen species are considered critically endangered, including the addax, the kouprey, the Bactrian camel, Przewalski's gazelle, the saiga, and the pygmy hog. Twenty-four species are considered endangered.