Sean B. Carroll has earned The Rockefeller University’s Lewis Thomas Prize for Writing about Science. He joins the ranks of such esteemed authors as Atul Gawande, E.O. Wilson, and many others. The much-deserved award honors him for an impressive body of work, including Brave Genius: A Scientist, A Philosopher and their Daring Adventures from the French Resistance to the Nobel Prize and Endless Forms Most Beautiful: The New Science of Evo Devo. We are proud to be publishing his next book, The Serengeti Rules: The Quest to Discover How Life Works and Why It Matters. Read on for a snippet from the book.
If you travel through the Serengeti, you’ll notice something odd. As you zip along in a dusty old Land Rover, your guide helpfully pointing out key elements of the surrounding flora and fauna, you’ll see vast herds of wildebeests existing in peaceful abundance. There’s nothing so very strange about that, but what is peculiar is that spotting a buffalo is a much rarer occurrence. Indeed, there are about 1,000,000 wildebeest populating the Serengeti, and only 60,000 buffalo. Why should that be?, you might wonder. At 450 kg, the buffalo is much less vulnerable to predation than the 170 kg wildebeest, after all. The answer can be found in The Serengeti Rules.
Serengeti Rule 6
Migration increases animal numbers
Migration increases animal numbers by increasing access to food (reducing bottom-up regulation) and decreasing susceptibility to predation (reducing top-down regulation).
Why are there about 50 wildebeest for every 3 buffalo in the Serengeti? Because wildebeests are constantly on the move and the buffalo stays put.
The two major ways to regulate population are predation and food limitation. The wildebeest is on a constant 600-mile path moving during the wet season toward the green, nutritious, short-grass plains and then, as the plains dry out, toward the tall-grass savanna and woodlands, which receive more rainfall than the open plains. This is how they feed themselves. How the effects of predation are mitigated is a bit more complicated. There are actually two types of wildebeest in the Serengeti. These include the vast migratory herds and the smaller pockets of “resident” populations. The hyenas and lions that prey on wildebeests cannot follow the herds because they are restricted to their territories as they raise their young. They find their food mostly in the smaller sedentary populations of wildebeests while the active ones roam free. The buffalo, meanwhile, are restricted by their sedentary lifestyle in procuring enough food to flourish quite as spectacularly as the smaller wildebeest.
Migration, then, is … [an] ecological rule, or more aptly a rule-breaker, a way of exceeding the limits imposed by density-dependent regulation.
For the first five Serengeti Rules and much more information on their ramifications both large and small, pick up a copy of The Serengeti Rules by Sean B. Carroll, coming in March 2016.