The Ngorongoro Conservation Area encompasses some of East Africa's most dramatic scenery and is one of the greatest of the world's wildlife wonders. The area, which is a mosaic of volcanic craters and calderas, hills, grass-covered plains, montane forests and marshes, provides habitats for a vast array of mammals, birds and reptiles. The western plains, adjoining the world-famous Serengeti, play host to thousands of wildebeest, plains zebra and gazelle for several months of each year, when the grasses emerge after the start of the rainy season. The Ngorongoro Crater is a microcosm of Africa. It has an abundance of resident game species and one of the continent's highest densities of lion and spotted hyena. Apart from its multitude of natural splendours, it is also an experiment in balancing the needs of the nomadic Maasai and the tourists, as well as the wildlife and vegetation. There are few places in Africa that can offer the diversity of species and scenery that are found in this northwestern corner of Tanzania.