The Ngorongoro Conservation Area (NCA) is a conservation area and a UNESCO World Heritage Site situated 180 km (110 mi) west of Arusha in the Crater Highlands area of Tanzania. The Ngorongoro Crater, a large volcanic caldera, lies within the area. Land in the conservation area is multi-use: it is unique, as it is the only conservation area in Tanzania providing protection status for wildlife whilst allowing human habitation. Land use is controlled to prevent negative effects on the wildlife population. For example, cultivation is prohibited at all but subsistence levels. The area is part of the Serengeti ecosystem and, to the north-west, it adjoins the Serengeti National Park and is contiguous with the southern Serengeti plains, these plains also extend to the north into unprotected Loliondo division and are kept open to wildlife through transhumance pastoralism practiced by Maasai. The south and west of the area are volcanic highlands, including the famous Ngorongoro Crater and the lesser known Empakai. The southern and eastern boundaries are approximately defined by the rim of the Great Rift Valley wall, which also prevents animal migration in these directions. The annual ungulate migration passes through the NCA, with wildebeest and zebra moving south into the area in December and moving north in June. This movement changes seasonally with the rains, but the migration will traverse almost the entire plains in search of food. The NCA has a healthy resident population of most species of wildlife: in particular, the Ndutu Lake area to the west has strong cheetah and lion populations.
A population of approximately 25,000 large animals, largely ungulates along with reputedly the highest density of mammalian predators in Africa, lives in the crater. Large animals in the crater include the black rhinoceros, and the hippopotamus, which is very uncommon in the area. There also are many other ungulates: the wildebeest the zebra, the eland, and Grant’s and Thompson’s gazelles. The crater has the densest known population of lions, numbering 62 in 2001. On the crater rim are leopards, elephants ,mountain reedbuck, and buffalo . In the middle of the crater there is a large lake inhabited by hundreds of flamingoes and from a distance, they appear as a pink border of the lake.
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 occur mainly near Lerai Forest; servals occur widely in the crater and on the plains to the west. Common in the reserve are lions, hartebeest, spotted hyenas and jackals. Cheetahs, although common in the reserve, are scarce in the crater itself. The African Wild Dog has recently disappeared from the crater and may have declined elsewhere in the Conservation Area as well, as well as throughout Tanzania.
The main feature of the NCA is the Ngorongoro Crater, a large, unbroken, unflooded volcanic caldera. The crater, which formed when a giant volcano exploded and collapsed on itself some two to three million years ago, is 610 m (2,000 ft) deep and its floor covers 260 km2 (100 sq mi). Estimates of the height of the original volcano range from fifteen to nineteen thousand feet (4500 to 5800 metres) high. Animal populations in the crater include most of the species found in East Africa, but there are no impalas (Aepyceros melampus), topis (Damaliscus lunatus), oribis (Ourebia oribi), giraffes (Giraffa camelopardalis), or crocodiles (Crocodylus niloticus).
The major water source in the crater is the Ngoitokitok Spring, near the eastern crater wall. There is a picnic site here open to tourists and a huge swamp fed by the spring, and the area is inhabited by hippopotamus, elephants, lions, and many others. Many other small springs can be found around the crater’s floor, and these are important water supplies for the animals and local Masaai, especially during times of drought. 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 species of wildlife in East Africa, with an estimated 25 000 animals within the crater.
The conservation area also protects Olduvai Gorge, situated in the plains area. It is considered to be the seat of humanity after the discovery of the earliest known specimens of the human genus, Homo habilis as well as early hominidae, such as Paranthropus boisei. The Olduvai Gorge or Oldupai Gorge is a steep-sided ravine in the Great Rift Valley, which stretches along eastern Africa. Olduvai is in the eastern Serengeti Plains in northern Tanzania and is about 30 miles long. It lies in the rain shadow of the Ngorongoro highlands and is the driest part of the region. The gorge is named after ‘Oldupaai’, the Maasai word for the wild sisal plant, Sansevieria ehrenbergii.
It is one of the most important prehistoric sites in the world and research there has been instrumental in furthering understanding of early human evolution. Excavation work there was pioneered by Mary and Louis Leakey in the 1950s and is continued today by their family. Some believe that millions of years ago, the site was that of a large lake, the shores of which were covered with successive deposits of volcanic ash. Around 500,000 years ago seismic activity diverted a nearby stream which began to cut down into the sediments, revealing seven main layers in the walls of the gorge.