Ngorongoro Conservation Area

Long, long ago, a giant volcano stood here.

After a big eruption, its top fell in. That left a huge round bowl. Today grass, lakes and swamps fill the bottom.

Britannica explains that Ngorongoro formed about 2.5 million years ago from a large, active volcano. After a major eruption, its cone collapsed inward, leaving a vast, round hollow called a caldera. The NCAA says the old volcano may have been nearly as big as Mount Kilimanjaro is today.

Ngorongoro is not alone. UNESCO says it belongs to a group of volcanic craters, including Olmoti and Empakaai, in the eastern branch of the Great Rift Valley, where the Earth's crust has been stretching for many millions of years.

Britannica describes Ngorongoro as an extinct volcanic caldera, thought to have formed about 2.5 million years ago when the cone of a large active volcano collapsed inward after a major eruption, leaving a vast, unbroken caldera; the NCAA compares the original volcano to the present Kilimanjaro in size. UNESCO's criterion (viii) calls it the largest unbroken caldera in the world, and places it with the Olmoti and Empakaai craters in the eastern Rift Valley, whose volcanism dates back to the late Mesozoic or early Tertiary.

The caldera floor is mostly open grassland, Britannica says, with a shallow soda lake, Lake Magadi, known for flamingos. The NCAA lists grasslands, swamps, rivers and woodlands on the floor, a mix of habitats that lets animals move in and out of the crater throughout the year.

Lions, elephants, buffalo, zebras and wildebeest live in the crater.

Rare black rhinos live here too. Pink flamingos wade in the salty lake. Every year, huge herds of wildebeest walk across the plains nearby.

UNESCO says some 25,000 large animals, mostly grazing animals such as wildebeest, zebras and gazelles, live in the area, along with one of the highest densities of predators in Africa. Britannica lists elephants, black rhinoceroses, leopards, buffalo, zebras, warthogs and gazelles on the crater floor, and very many lions.

Ngorongoro is also part of one of the largest animal migrations on Earth. Each year well over a million wildebeest, along with zebras and gazelles, move through the area and give birth on the short-grass plains on the edge of the Serengeti. About 500 kinds of birds have been recorded, and flamingos gather on the crater's soda lake.

UNESCO's criterion (x) describes some 25,000 large animals, mostly ungulates, alongside the highest density of mammalian predators in Africa, including the densest known lion population (an estimated 68 in 1987), and endangered species such as the black rhino, African wild dog and golden cat, with about 500 bird species. The area supports over 1 million wildebeest, 72,000 zebras and about 350,000 Thomson's and Grant's gazelles, which calve on the short-grass plains straddling the boundary with Serengeti National Park.

The area's habitats vary with altitude and climate: short-grass plains, highland catchment forests, savanna woodlands, montane long-grass plains and high open moorlands. UNESCO notes that poaching remains a continuing threat requiring patrols, that invasive species need monitoring, and that tourism pressure from visitation, infrastructure, traffic and waste is a concern.

Maasai families live in the conservation area. They keep herds of animals, such as cattle.

Scientists have also found very, very old footprints and bones here. They help us learn how the first humans lived.

Ngorongoro was set up in 1959 as a place where people and wildlife share the land. Maasai pastoralists, herders who move with their animals, graze their livestock here, and Britannica notes that some graze cattle in the crater itself.

The area is also one of the most important places in the world for learning about human origins. UNESCO says that at Laetoli, scientists found fossilized footprints made by early relatives of humans walking on two legs. At Olduvai Gorge, a ravine about 14 kilometers long, they have found fossils of several kinds of early human relatives and their stone tools.

UNESCO describes Ngorongoro as a multiple land-use area where wildlife coexists with semi-nomadic Maasai pastoralists practicing traditional grazing; at inscription in 1979 an estimated 20,000 Maasai lived in the property with about 275,000 head of livestock, and no permanent agriculture is officially allowed.

In 2010 the area was added to the World Heritage List for its record of human evolution, the product of more than 80 years of archaeological research spanning almost four million years. UNESCO cites the fossilized footprints at Laetoli, linked to the development of walking on two legs; a sequence of hominin species in the 14 km Olduvai Gorge, from australopiths such as Zinjanthropus boisei to Homo habilis, Homo erectus and Homo sapiens; an early form of Homo sapiens at Lake Ndutu; and evidence in the crater of developing stone technology and the transition to iron. Several type fossils of the hominin lineage come from here.

Visitors watch the animals from inside a safari car.

Stay in the car and be quiet. Never throw things or feed the animals. Take all your trash with you.

The Ngorongoro Conservation Area Authority asks all visitors to stay in their vehicles except in special areas, and only four-wheel-drive vehicles may go down to the crater floor. Walking safaris are not allowed inside the crater, though walks are possible on the rim.

Keep at least 25 meters from animals, stay quiet, and don't honk, clap, play music or imitate animal sounds. Never throw anything at animals or feed them. Driving is allowed only from 6 a.m. to 6 p.m., with a speed limit of 25 kilometers an hour in the craters, and all litter must be taken out.

The NCAA's visitor guidelines require visitors to remain in vehicles except in designated areas; only four-wheel-drive vehicles up to 3,500 kg tare weight may descend to the crater floor (except authorized trucks for organized groups), and off-road driving is banned without the Conservation Commissioner's permission. No more than five vehicles may gather at an animal sighting, in silence, and drivers should keep at least 25 m from animals; speed limits are 50 km/h in the area and 25 km/h at the craters, with driving permitted from 06:00 to 18:00.

Visitors must not feed animals, throw objects to attract them, play audio, sound horns or imitate animal calls, and must take their litter back to their lodge or camp. These rules address the tourism pressures UNESCO identifies, including traffic, waste and disturbance to wildlife.