Often described as one of the great natural wonders of the world, the Ngorongoro Conservation Area became an UNESCO World Heritage Site in 1979. It features the Ngorongoro Crater, the world's largest unbroken volcanic caldera. Eight million years ago, the crater was an active volcano but its cone collapsed, forming a 610-meter deep crater, with sides so steep that it has become a natural enclosure for a very wide variety of wildlife, including most of the species found in East Africa.

Although quite large, covering an area of 311 sq. km the 20-kilometre wide crater accounts for just a tenth of the Ngorongoro Conservation Area, which also includes the still active Ol-Ndoinyo Lengai volcano (meaning "Mountain of God" in the Maasai language), which last erupted in 1983, and the Olduvai Gorge, where the Leakeys, a family of renowned archaeologists, discovered the remains of a 1.8 million year old skeleton of Australopithecus boisei, one of the distinct links of the human evolutionary chain (indeed, fossils show that the area is one of the oldest sites of hominoid habitation in the world).

Home to the densest population of mammalian predators in Africa, the Crater gives shelter to some 25,000 large mammals, mainly ungulate. Most East African animals can be found in the crater, with the exception of Topi, Impala, and Giraffe (the latter because there isn't enough acacia to browse, the former probably due to fierce competition from wildebeest).

Ngorongoro is one of the last places in Africa where to reliably see the endangered black rhino, as a small population lives pretty much undisturbed. Although a population of almost 100 rhinos lived here in 1965, by the mid 80s poaching had almost completely eradicated them, reducing their numbers to under 5 individuals. After severe intervention by the Tanzanian government (including 24-hour ranger surveillance), the population has slowly recovered to the actual (2004 census) 17 individuals.

Predators are common sights in the crater, including cheetahs, hyenas, jackals, and the magnificent black-maned lions. Leopards and the night-goers (serval, ratel, and bat eared fox) are much more elusive. There are four prides of lions (more than 60 individuals estimated) and six clans of hyenas in the Ngorongoro crater, with the cats descending from only 15 lions that either survived or invaded the crater after a plague of biting flies in 1961.

Animals found in the Ngorongoro, besides the mentioned before, include wildebeest (7,000 estimated in 1994), zebra (4,000), eland, Grant's and Thomson's gazelle (3,000), hippopotamus (though very uncommon), hartebeest, waterbuck, warthog, mountain reedbuck, buffalo, and elephant. Oddly, elephants found in the crater are predominately old bulls who survived, inside the relative safety of the crater, the pre-ivory ban days in the 1980s. These are probably the largest elephants to be found in the Serengeti ecosystem. No females are known to inhabit the crater.

Birds also abound in the Ngorongoro Conservation Area, with over 500 species recorded, including important populations of white pelican, and greater and lesser flamingo on Lake Makat in Ngorongoro crater, Lake Ndutu and the Empakaai crater lake where over a million birds foregather. Other bird specied include ostrich, Ruepell's griffon, Verreaux's eagle, Egyptian vulture, lesser falcon, Fischer's lovebird, and Jackson's whydah

Contrary to what is commonly thought, the crater is not a self-contained ecosystem and some animals do migrate in and out, though not in significant numbers. Most of the animals are resident and remain year-round, with 20,000 to 30,000 large mammals to be found at any given time within the Crater walls.

With excerpts from Wikipedia and the United Nations Environment Programme World Conservation Monitoring Centre. Photo by eismcsquare displayed under a Creative Commons Licence.