The Mara is a beautiful but sensitive environment that can survive only if properly respected. Well-watered by the Mara River, enjoying abundant vegetation, wildlife and rainfall, its ecology would appear, at first sight, to be relatively resilient. It also appears to have withstood the erosive effects of huge numbers of visiting tourists extraordinarily well. There are signs, however, that the delicate balance between tourist numbers and wildlife populations cannot be properly maintained for much longer as evidenced by the reduction in the protective vegetation cover and the emergence of a series of dust bowls. Meanwhile, the Reserve is host to 95 species of mammals, amphibians and other reptiles and 485 species of birds. During the dry season (July to October) it also hosts a major concentration of migratory herbivores including about 250,000 zebra and 1.3 million wildebeest. Amongst the list of easy-to-view species are: gazelle, elephant, topi, buffalo, lion (Kenya's largest population), black rhino, hippo, hyena, giraffe, leopard and mongoose.