What initially triggered McNaughton to shift his inquiry? Perfect timing with one of nature's most spectacular eventsthe annual migration of 1.5 million wildebeest from the northern borders of the Serengeti National Park, where tall-grass vegetation and rain are usually plentiful, to their calving grounds in the dry, short-grass plains of the southeast. Their arrival, like clockwork, coincides with the rainy season there, as once bone-dry lands brighten to an emerald green. The wildebeest mow their way through the vegetation with thousands of other ungulates like zebra, buffalo, and gazelle. Upward of 500,000 wildebeest calves are born during this time and, as the dry season's return nears, the herds again begin their trek north.
McNaughton was just getting his research under way in spring 1974, when along came those odd-looking creatures on their journey. Now, with all that chomping and stompingnot to mention the urinating and defecatingMcNaughton theorized that those animals were major players in the system, and his field experiments confirmed it. Grass in plots he had fenced off from the grazing herds was drying out. "The areas they'd grazed were regrowing and producing tissues of very high quality with a high nutrient content," he says. "Initially I wasn't very interested in the animals at all, but then I thought, 'Wow, these animals are having an impact.'"
Such knowledge may be a given for today's ecology researchers and students. Back then, however, it was a startling discovery that rocked the conventional wisdom of grasslands ecosystem studies. Some even branded McNaughton a heretic, but his evidence proved irrefutable. "What shocked the ecological community was how powerful this approach was and how the effects of these animals cascade throughout all compartments of the ecosystem," Frank says. "In a way, it rejuvenated the field."
SIZING UP AN INSPIRATIONAL ECOSYSTEM
Through a quarter century of studying the Serengeti, McNaughton, who has taught at SU since 1966, says the overarching question of his research hasn't really changed: "How can the energy of the sun, with no human input, support such an enormous number of animals and do so without the destruction you see where humans raise livestock?" McNaughton says. "We now know a lot of the answers to that question. We know the reason wildebeest are so abundant is that they move around with reference to the rains, so they have a much greater food source than non-migratory animals do. We know non-migratory animals concentrate in hot spots for nutritional reasons. We know the wildebeest go back to the Serengeti Plains to have calves, which, for nutritional reasons, grow up there the first few months of their lives. We learned that mobility is very important in terms of keeping the area from being destroyed. It's a rest-rotation grazing systemthey feed very heavily and then move on."