Elephants, lions, buffalo, hippopotamuses, rhinoceroses, giraffes, antelopes, leopards, cheetahs, hyenas, and many species of snakes are found here, although most large carnivore populations have been drastically reduced since the early 20th century. Elephant poaching, particularly in the south of the country in areas such as Zakouma National Park, is a severe problem. The small group of surviving West African crocodiles in the Ennedi Plateau represents one of the last colonies known in the Sahara today.