WALK ON THE WILD SIDE

Most visitors to Africa experience its wildlife from the safety of a Land Rover. But on a walking safari, things get real fast.

THE FIRST THING WE NOTICED WERE THE vultures, about a dozen of them, perched on the f lat top of a tall acacia tree. Every so often, two or three of the birds, white-feathered and ominous, would swoop down into the tall grass, remain out of sight for a few moments, and then return to their perch. “Something has definitely been killed,” Mark Thornton said. “Let’s go see what it is.” He paused a beat. “Of course, whatever killed it is still around here, too.” We were deep in a swath of largely untouched wilderness in Serengeti National Park. The closest human was perhaps 75 miles away. Our plan was to set off on foot, but first Thornton, a veteran safari guide in Tanzania and one of the few guides in all of Africa to lead multiday walking tours of the bush, laid down some ground rules. “We walk single file, and we stay quiet,” he said. “That way we hear things.” He went on. “If a lion or a buffalo appears, do not run. You’ll be scared, but stay behind