No other place on Earth boasts such a wide variety of wild animals so close to a bustling metropolis. Lions, giraffes, and ostriches roam freely against a backdrop of skyscrapers and jets landing at Kenya's international airport. But because of people moving in and fences going up in areas around the Nairobi National Park, zebras and wildebeest - and the lions who stalk them - may soon have no way of migrating to southern grasslands during the rainy season and back into the park, where water is plentiful during the dry season. Now the government and wildlife foundations are paying the Maasai, the famed warrior tribe of central Kenya, to not farm or fence in some land as a way to keep the migration corridor clear.