What has six million hooves and sounds like a bullfrog?

The wildebeest of the Serengeti!

A species of antelope, the ungainly wildebeest is a high-shouldered grazing machine with a glossy brown coat marked by vertical stripes of longer black hair. A full, white beard runs the length of its stocky neck, and C-shaped horns curl above the flat, black face of its huge head. About 1.5 million wildebeest now follow a clockwise, 500-mile migration route through northern Tanzania and Kenya.

Visitors to the Serengeti traveling from November to July are likely to see the migratory herds at some stage of their continual cycle. It is something of an art to predict where the wildebeest will be at any particular time of year. Weather conditions, especially droughts, determine where the grass grows and where water can be found. Wildebeest need to drink at least every two days, so they cannot live far from a reliable source of water. During the rainy season, white-bearded wildebeest of the subspecies Conochaetes taurinus mearnsi drink from pools and eat short grass that grows in the volcanic and alkaline soils of the southeast Serengeti, a Maasai word meaning "endless plains."

As the rains cease, usually in mid-May, the short grass turns brown, the pools dry up, and the wildebeest move westward. They cross the savanna to reach the tall grasses and water holes found in the woodlands closer to Lake Victoria. The Serengeti wildebeest rut occurs at this time, a mega-mating ritual described as "unbelievably spectacular" by Richard Estes, a world-renowned wildebeest expert. (See "The Wildebeest Rut") The ground loses its moisture, thunderstorms rumble less often, and the herds move north from the woodlands into the northern Serengeti and Kenya's Masai Mara Game Reserve. Usually in August-October, the wildebeest herds reach the northern point of their migration.

In November the short rains come, and the wildebeest wander south toward the short-grass diet they prefer. Gradually they make their way down through the eastern Serengeti, trampling the ground, covering it with manure, rolling and pawing to mix up an extremely rich soil. As they feast on the short grass, fattening up during December-January, they are assisted by the industrious dung beetle.

Ball-Playing Dung Beetles

The lowly dung beetle, also known as a scarab beetle, rolls up a ball of wildebeest dung, deposits an egg inside, and buries it. Billions of dung beetles do the same. New beetles hatch to roll up new dung. Dung beetles deserve much of the credit for the success of the wildebeest, which has become the most numerous mammal in the Serengeti They fertilize the soil as they clean the plains, providing an ideal environment for wildebeest to grow and multiply. "One day you may see thousands of wildebeest all massed together," said Rick Thomson. "The next day they will have moved on, and there will be no sign of dung where they were standing. The dung bettles have buried it all, overnight."

Wildebeest calving
For a mere three weeks, usually in February, wildebeest calves are born at a terrific rate. On the short-grass plains, which offer no cover from predators, thousands appear every day. Sometimes they disappear as well. Rick Thomson said he has seen a cow get up in the midst of calving, the baby's legs protruding from her body, and run away. The calf goes back inside to wait for a more convenient time to be born.

Newborns may become prey to lions, hyenas, and other predators. Because so many calves are born in such a short time, however, the predators simply can't eat them all. Big cats like lions, cheetahs and leopards are territorial and do not migrate with the wildebeest herds. They remain within their own boundaries throughout the Serengeti and adjoining lands as the wildebeest pass through.

No baby hoofed mammal gets to its feet faster than a wildebeest. The record is three minutes! On average, a baby can rise and walk seven minutes after birth, and within two days it can keep up with its mother as she runs with the herd.

Through March -May the wildebeest remain on the short-grass plains of the southern Serengeti. When they reach the peak of their physical condition in June, or thereabouts, they begin the annual rut. The cycle begins again.

The Serengeti wildebeest migration is one of the largest land mammal migrations on Earth, second only to that of Mongolian gazelles. The wildebeest's ancestral routes are preserved in a triumph of conservation by the Government of Tanzania, which oversees most of the Serengeti ecosystem under its Protected-Area system. In Tanzania, the wildebeest routes cross Serengeti National Park, Ngorongoro Conservation Area, the Maswa Game Reserve, and the Loliondo Controlled Hunting Area.

To see the wildebeest migration at any time of year is to witness an ecological drama on a 15,500-square-mile stage, a marvel of mass movement and species adaptation