GREAT MIGRATION

THE earth thunders with the sound of a million pounding hooves. The mass of heaving bodies surges forward, kicking up a billowing cloud of red dust. The animals gallop on spindly legs as the herd moves past rolling valleys and hills, crosses open grasslands, and traverses rivers and streams. They advance in a great wave, leaving behind huge swaths of grass cropped down to the roots. This vast herd of bellowing, stampeding creatures makes up one of the greatest natural wildlife spectacles on earth—the great migration of wildebeests.

An estimated 1.5 million wildebeests roam the Serengeti. This is an odd-looking creature, with a long head and glossy eyes, which are located far apart and high up on the skull. Its cowlike horns curve slightly downward and outward and then hook upward. Its back slopes down toward hindquarters that appear weak and out of proportion to the animal's strong shoulders and neck. Thin, spindly legs support the weight of the wildebeest's heavy body. With a long whitish beard under the chin, a dark mane on the neck, and a tail like that of a horse, the wildebeest resembles a combination of several different animals.

The antics of wildebeests are often clownish and entertaining. When gathered in large herds, they produce a noisy bellowing sound that resembles a chorus of thousands of frogs. Standing on the open plains, they seem to wear a bewildered, surprised look as they stare out at the world around them.

At times, a wildebeest bull will race across the plains, prancing sideways and running in circles. Tossing his head, he bucks and bounces on stiff legs, kicking up dust in a comical manner. Some say that these actions are intended to impress females or to warn other males with a show of prowess. Sometimes, though, the bull just appears to be feeling frisky.

Born Into a Hostile World
When the time is right, the wildebeests begin giving birth. They have the unique ability to synchronize the birth of their young, dropping 80 to 90 percent of their calves within a three-week period. During this time the herd swells with thousands of bleating baby wildebeests. Each mother must quickly bond with her calf, for if the herd stampedes, the mother and her calf could easily become separated, and the calf would have little chance of survival on its own.

The young are born into a hostile world of ever-watchful predators. Females wait until there are no signs of danger before giving birth. However, if surprised by a predator, they have the incredible ability to interrupt the birth process and run away. Then, at a later time when no danger threatens, they are able to complete the birth of their calf.

The calf itself seems to have an inborn sense of danger and is on its feet within a few minutes of birth. After a week, the youngster will be able to gallop across the plains at 30 miles [50 km] per hour.

A Time to Move
Wildebeests migrate in great herds across the Serengeti. The key to their mass movement is the rain. The rainfall is governed by weather patterns that move in annual cycles. Throughout the year it is usually raining somewhere within the bounds of this vast grassland.

Wildebeests need water daily and must have a constant supply of grass to feed on. As long as food and water are available, they stay put. But as the dry season progresses, the grass on the plains begins to dry up and water sources disappear. The herds of wildebeests cannot wait for the rains to come to them. They must follow the rain.

Wherever the rain falls, the dry plains are quickly transformed. Within a few days, green sprouts push up through the soil and produce a green flush of grass. These tender blades are full of nutrition and moisture—a powerful attraction for wildebeests.

These creatures have an ability to detect rainfall, even at great distances. No one is sure how they know that it is raining in another part of the Serengeti—whether it is by seeing the billowing thunderheads towering in the distance or by smelling the moisture in the dry air. At any rate, to survive, the herds must move. And move they do!

A Perilous Journey

Herds must cross swift-flowing rivers


In the beginning the departure is gradual. Wildebeests are gregarious creatures; when one animal starts to walk in a certain direction, others around it stop grazing and try to follow. Soon the whole herd is surging forward in a dramatic exodus. Pushed by thirst and hunger, they move onward. Sometimes they run. At other times they plod along in drawn-out lines, creating deep ruts in the dusty soil.

Their journey is fraught with danger. Predators follow the immense herds of ungulates, keeping a keen eye on any animal that is slow-footed, lame, or sick. As the wildebeests advance, they enter the territories of lion prides, which wait in ambush. Hiding in the long grass, the big cats rush into the mass of grazing animals, causing them to scatter in panic. Leopards, cheetahs, wild dogs, and hyenas all take advantage of any animals that fall behind or drift away from the main herd. When a kill is made, vultures appear. Squabbling and fighting over the remains, they leave nothing behind but a frame of bones, which bleach white in the hot African sun.

Swift-flowing rivers create formidable barriers that the herd must cross. River crossings are spectacular events, with thousands of animals plunging from high banks into the water below. Most make it safely to the opposite side. Others are carried away by the current or are taken by the crocodiles that wait just below the surface of the water. This perilous journey is undertaken yearly. When completed, it may cover a distance of some 2,000 miles [3,000 km].

Man—The Greatest Predator

For thousands of years, man had little impact on the migration of the wildebeests. Now man poses the biggest threat to this spectacle. In recent decades the governments of Tanzania and Kenya have endeavored to protect the animals of the Serengeti. Yet, even though the wildebeest migration takes place largely within the protected borders of wildlife sanctuaries, thousands of the animals are illegally trapped and killed by poachers. Armed with wire snares, poison arrows, and guns, they hunt animals to supply game meat and trophies to eager buyers. An army of game wardens and rangers patrol the protected areas, but the Serengeti is so large that it is almost impossible to protect it fully. As human populations grow, the pressure to encroach on these fertile grasslands increases. The setting aside of large tracts of land for wildlife is a bitter issue that is constantly debated.

At one time millions of bison roamed the plains of North America. Now they are gone. Some fear that the same fate awaits the last great herds of wildebeests in East Africa. It would be a sad day if we were to witness the disappearance of such an awesome natural wonder.