That interaction is not always heartening. During several weeks of exploring the Serengeti and Ngorongoro region, I confirmed many reports of human-wildlife conflict—an elephant stomping and killing a villager armed with a bow and arrow in Robanda; black rhinos bolting in Ngorongoro Crater, where tourists in cars had approached too fast and too close, sending the animals fleeing; poachers setting out hundreds of wire snares on the park's western borders in hope of snagging a wildebeest, a zebra, or some other protein-rich ungulate for the table or for the lucrative traffic in wild meat. The illegal bush-meat trade, a rising threat in almost all of Africa's protected areas, annually feeds an estimated one million people in northern Tanzania alone.

The wire snare—preferred by poachers because it is a cheap and silent method of taking game—is also indiscriminate, grabbing any passing animal unlucky enough to step into a noose secured to a tree. This method recently hooked a Serengeti giraffe around the leg, a lioness around the neck, and a wildebeest by the horns. Another lion, snared in the western corridor outside the park, wrestled himself free of his wire noose, cutting off his hind leg in the process; he has been seen galumphing through the bush on three legs, a sturdy survivor who dominates his territory. He said, "but I can tell you we don't see very much of that money here."

Twenty years ago, when the pressures of population were less, few Serengeti scientists worried unduly about poaching. "It would not be correct to call killing an antelope or zebra or wildebeest to feed one's family meat poaching," said Markus Borner, the Frankfurt Zoological Society's top scientist in the region, interviewed for a National Geographic article in 1986. Now, however, with the market for wild meat flourishing in Africa, villagers around the park can make more money by hunting in the Serengeti than they can by almost any other activity, so the annual harvest of animals in the ecosystem has risen dramatically in recent years. Because hunting is illegal, precise figures are hard to come by. Estimates of the poaching toll range from a low of 40,000 animals a year to a high of 200,000, most of them wildebeests. Such a harvest cannot be sustained at the higher figure without causing fundamental damage to the ecosystem.

"You can only remove so many nuts out of an airplane before it falls out of the sky and crashes," said Rian Labuschagne, managing director of the Grumeti Reserves, an enterprise that recently leased almost 280,000 acres (110,000 hectares) of hunting concessions in the western Serengeti to restore the beleaguered ecosystem from the outside in.