It is not often in life that we get the opportunity of watching massive herds of animals migrate, so when I got the chance to see the annual wildebeest migration, I knew I had to go.
Over 1.5 million wildebeests migrate annually to find better pastures for food. Although most migrate northwest in May or June at the end of the rainy season, some also migrate southwards towards Ngorongoro Crater. They move back to the high Serengeti plain between December and March.
Although the migrations typically occur towards the end of May, the rainstorms can either advance or delay the date when storms are more frequent. A week before the migration starts, the self-contained groups gather in one part of the high plateau, forming one large herd of adult males, females, and calves.
Quest for food
The great migration of wildebeest is to move to their summer feeding grounds. The migration is classed as trophic or alimental and is commonly called the feeding migration. If there were enough food where they were, the great migration wouldn’t happen.
The great migration takes place at generally the same time every year, depending on the amount of rainfall. Once the vegetation is exhausted, the migration will happen, and they will move on to new, fresher pastures.
Without moving on to the new feeding grounds, many wildebeest wouldn’t survive. Starvation would set in for thousands of wildebeest without the migration for food.
These large herds move steadily towards their summer grounds. They will stop to avoid storms, and the herd may split up into two groups. The first will head north, moving in the direction of the shrub-covered hills and valleys near Benagui and Kilimafeza towards the banks of the Mara River.
The other group will head westward, following the river beds that flow through to Lake Victoria. Once they find water, they will also find enough fresh grass to sustain them.
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Wildebeest are also known as gnus, and the gnu is one of the sounds they make. With thousands of them altogether, this makes a once-in-a-lifetime sound. Wildebeests are not the only animals that make the migration, but small groups of zebras and larger herds of antelopes.
The group starts to move on a north-westerly course, constantly moving. This is very much unlike the chaos of American bison stampeding. They form long lines, leaving trenches in the ground behind them from their hoofprints.
There is also another group that heads southward down to Oldangua in preparation for climbing the slopes of Ngorongoro. They will then spend the dry season feeding on the vegetation growing in the volcanic crater.
These wildebeests will mix with the other wildebeest that stay in Ngorongoro year-round in an area ten miles in diameter. There are approximately 7,000 sedentary wildebeest, and these are grouped into herds of fifty to over a thousand.
About 30% of these wildebeest are in even smaller groups, consisting of about ten females and their calves and a territorial male.
These animals can live in Ngorongoro year-round due to the abundance of food created by the swampy volcanic soil and high rainfall. Even though they have enough food to survive, about 20% will migrate about eight miles away to a moist valley separating the plain of the Serengeti from the uplands. Once the rainy season has passed, they will journey back to Ngorongoro.
Month by month
Although these times depend on the rainy season, these are general times for the great migration.
- November and December – arrive on the high plains of the Serengeti
- January, February, and March – stay on the high plains and give birth
- April – Most animals will start their migration
- May – Migration is firmly underway
- June – Wildebeest congregate in the Western Corridor
- July and August – Many will head through the Serengeti National Park
- September – Crossing the Mara River into Kenya
- October – Following the rains and heading south back to the high plains of the Serengeti
Reproduction
Summer lasts for about five and a half months, and during this time, the small family units and the larger herds will reorganize themselves. Young calves will mature near their mothers, and adult females will become pregnant again, ready for the journey back to the Serengeti.
Although the primary reason for the great migration is food, the breeding cycle also happens. Once the herds reach their homelands, the females will give birth to the young.
Returning to the Serengeti
In October, the plains of the Serengeti dry up with life. Although a few flocks of sand-grouse may be seen, the plains are empty compared to when thousands of animals shook the ground with their hooves.
November and December are when the light rains start, which signifies the start of the return of the gigantic herds. In January, when the herds have returned, the females start giving birth. With grass now growing again, new life is also born.
For the next sixteen years, these calves will grow and take part in the great annual migration, journeying from the high plain of the Serengeti to the banks of Lake Victoria.