The Ngorongoro Conservation Area or NCA is a conservation area situated 180 km west of Arusha in the Crater Highlands area of Tanzania. The conservation area's boundaries follow the boundary of the Ngorongoro Division of Ngorongoro District. It is 8,288 km² - about the size of Crete.
A population of about 25,000 large animals, largely ungulates along with the highest density of mammalian predators in Africa, lives in the crater. These include black rhinoceros, and hippopotamus which are very uncommon in the area. There are also many other ungulates: wildebeest, zebra, eland, Grant’s and Thomson’s gazelles. The crater has the densest known population of lion numbering 62 in 2001. On the crater rim are leopard, elephant, mountain reedbuck and buffalo. However, since the 1980s the crater’s wildebeest population has fallen by a quarter to about 19,000 and the numbers of eland and Thomson’s gazelle have also declined while buffalos increased greatly, probably due to the long prevention of fire which favours high fibrous grasses over shorter less fibrous types.
In summer enormous numbers of Serengeti migrants pass through the plains of the reserve, including 1.7 million wildebeest, 260,000 zebra and 470,000 gazelles. Waterbuck mainly occur mainly near Lerai Forest; servals occur widely in the crater and on the plains to the west. Common in the reserve are lion, hartebeest, spotted hyena and jackal. Cheetah, though common in the reserve, are scarce in the crater itself. Wild dog has recently disappeared from the crater and may have declined elsewhere in the Conservation Area as well.
The main feature of the Ngorongoro Conservation Area is the Ngorongoro Crater, which is the world's largest unbroken volcanic caldera. The crater is 610m deep and the floor is 260km squared. The steep sides of the crater mean that it has become a natural enclosure for a very wide variety of wildlife, including most of the species found in East Africa.
Aside from herds of zebra, gazelle and wildebeest, the crater is home to the "big five" of rhinoceros, lion, leopard, elephant and buffalo. The crater plays host to almost every individual specicies of wildlife in East Africa, and there are an estimated 25,000 animals within the crater. Lake Magadi in the centre of the crater is, like many in the rift valley, a soda lake supporting flocks of flamingo.