The areas occupied by the tsetse fly were largely barred to animal husbandry. Sleeping sickness was dubbed "the best game warden in Africa" by conservationists, who assumed that the land, empty of people and full of game animals, had always been like that. Julian Huxley of the World Wildlife Fund called the plains of east Africa "a surviving sector of the rich natural world as it was before the rise of modern man". They created numerous large reserves for hunting safaris. In 1909 the newly retired president Theodore Roosevelt went on a safari that brought over 10,000 animal carcasses to America. Later, much of the land was turned over to nature reserves and national parks such as the Serengeti, Masai Mara, Kruger and Okavango Delta. The result, across eastern and southern Africa, is a modern landscape of manmade ecosystems: farmland and pastoral land largely free of bush and tsetse fly; and bush controlled by the tsetse fly.