The Great Wildebeest Migration
With 1.4 million wildebeest, 250,000 Burchell’s zebra and a smattering of trailing Thomson’s gazelle making the annual round trip, it's no wonder the Great Wildebeest Migration within Tanzania’s Serengeti and the Maasai Mara in Kenya is one of nature’s greatest spectacles. The herds make the 1,200-mile oval circuit with two things in mind: food and water and, along the way many migrating animals fall to predators including lion, cheetah, crocodile and hyena. Each year, the herds traverse over a combined area of approximately 25,000 sq km (10,000 sq miles) and the mind-boggling scope and raw beauty of so many mammals moving en masse can be best experienced in different areas during different seasons. This guide explains which parts of the Mara-Serengeti ecosystem are most productive through each of the seasons of the year, including the two main highlight events most popular with visitors; the calving in the southern Serengeti and Ngorongoro Conservation Area between January until March and when the herds are in the vicinity of the Mara River between June and October in the Maasai Mara and the northern Serengeti
MOVING SOUTH/DANGERS ABOUND The vast herds are returning south through the Serengeti, having depleted the feeding grounds in Kenya’s Maasai Mara Game Reserve. Their final destination is the short grass plains of the southern Serengeti, in the shadow of the Ngorongoro Highlands. The resident carnivores of the southern Serengeti have been eagerly awaiting the return of the herds and the rains that have started in the south are a sure sign of their imminent arrival.
December: Central Serengeti
January - March: Southern Serengeti & Ngorongoro Conservation Area
on the move again Now around 2 months old, the calves are strong enough to begin the trek northwards. Still keeping close to their mothers, they leave the relative safety of the open short grass plains in large herds and move towards the hills and sparse acacia woodland of the central Serengeti. This is the peak of the ‘Long Rains’ season and herd location can vary dramatically from year to year, completely driven by localised rainfall patterns and very difficult to predict in advance. This, coupled with often unpassable roads, means there are generally fewer tourist visitors to the Mara-Serengeti ecosystem at this time.
April - Mid May: Central Serengeti
CALVING & THE SURVIVAL OF THE FITTEST As the herds arrive on the short grass plains of the southern Serengeti and Ngorongoro Conservation Area, the heavily pregnant females gather in groups for safety in numbers against the variety of predators. From late January, young wildebeest begin to appear across the plains however the calving season reaches its’ peak in mid-February when 90% of the several hundreds of thousands of calves born each year are dropped over a two week period. Walking within 5 minutes and running amongst the herd within 10, these youngsters must immediately adapt to the dangers of their new world.
OVER THE BORDER Leaving the Western Corridor, the herds splinter again as they flood north, through acacia woodland and towards the northern extreme of their migratory route. The rut continues through the rest of June and, by early July, several exhausted males have become separated from the relative safety of the main herds and are picked off by predators waiting in the wings. During this period, the wildebeest reach the Kenyan border and cross into the Maasai Mara, which they abandoned at the end of the previous year. Over the intervening months, the ‘Long Rains’ of April and May have fuelled the growth of the grasslands. In many places the grass is nearly 2m (5ft) tall and all that can be seen of the first arrivals is horns and ears protruding out of the top, but they soon begin the process of trampling and grazing this down.
Mid May - Mid June: Western Serengeti
THE 'WESTERN CORRIDOR' The Western Corridor is the arm of the Serengeti that stretches towards Lake Victoria. Running down much of the length of it is the Grumeti River, home to some of the largest crocodiles in East Africa. Although their time in the Western Corridor only lasts a few weeks, the wildebeest herds tend to join and swell into larger aggregations as they mass on the southern side of the river, which they must then cross to continue their journey north, away from the increasingly arid southern Serengeti and towards the long grass plains of the Maasai Mara. June also marks the start of the rutting season. Large males establish mobile territories around themselves; areas into which they welcome as many females as possible whilst fighting away competitors in impressive horn clashing displays.
Mid June - July: Northern Serengeti & Maasai Mara
August - October: Maasai Mara & Northern Serengeti
November: Northern Serengeti & Maasai Mara
DANGER IN THE WATER - THE MARA RIVER One of the most spectacular events of the annual migration is when the herds cross the mighty Mara River to access grazing on the other bank. Typically, numbers build up on the plains close to the river then edge ever closer until the simple pressure of numbers forces the first animals to take the plunge … and once the flood doors open the whole herd follow suit. River crossings are extremely dangerous – steep banks and fierce currents coupled with the large numbers of animals involved can lead to catastrophic consequences. In addition, lurking below the waters’ surface are Nile crocodiles who, for much of the year, have been patiently awaiting the arrival of the herds and now make the most of this time of plenty.
CONTINUE THE ENDLESS TREK After several months in the north, the grazing has all been used up and the majority of the herds have started to turn away from the Maasai Mara and trek south through the Serengeti. Some predators and scavengers will follow them throughout the year, whilst other begin a long wait for their return. The progress of the herds is dictated by access to food and water. As November marks the start of the ‘Short rains’ season, one big rainstorm can change the direction of the herd, causing them to halt in their tracks or even backtrack north or, in other cases, surge further ahead on the journey south.
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