Circling the Great Migration

“No one can return from the Serengeti unchanged, for tawny lions will forever prowl our memory and great herds throng our imagination” – George Schaller

The survival of the fittest spectacle, the annual Great Migration, has been described as the “seventh wonder of the modern world.” The ocean of migrating ungulates takes place on the Serengeti Mara Ecosystem. This is made up by the Ngorongoro Conservation Area in the south (the Serengeti National Park) and the neighbouring Maswa Game Reserve, and other areas in the centre, east and west, and the Masai Mara Game Reserve to the north. The wildebeest are the principle migrators reaching millions in number and are followed by the other main migrators, such as Thomson’s gazelle, zebra, and eland. There is also a collection of other resident herbivores, and unsurprisingly, eager predators ranging from lions to hyenas, leopards, cheetahs and other smaller predators.

There is neither a beginning nor an end to the wildebeest’s on-going search for water and food, and so it is hard to view the migration as a single event. It is essentially an unrelenting circle around the Serengeti-Mara ecosystem and a constant sequence of life and death. Having said this, the migration is a dynamic process and it is very difficult to predict the routes and the best months to view this spectacle accurately. No two years are the same, and the herds’ movements are always different. It is considered that the most influential and probable influence on the herds’ movements is the weather and the annual four season cycle. These can be sensibly classified as: December-February/March is the ‘short dry season’; March through April and into May ‘long rains’ fall over a six week period; and June-September is the ‘long dry season’, with ‘short rains’ falling between October into November.

The calving season

To ‘begin’ the migration we will start from January and February, the wildebeests calving season. Hundreds of thousands of calves are birthed in a coordinated birthing and this unfolds on the short grassy plains that envelope the hills of the Ngorongoro Crater highlands and are spread around Olduvai Gorge, the historically fossil rich ‘cradle of mankind.’

The annual calving season offers hungry and eager predators an easy feast, and driving across the plains between the blanket of ungulates and their calves, one is guaranteed to see remarkable sightings of lions, hyenas, and cheetah to name just a few. These predators actually only have a limited impact on the population of new-born calves, as they shortly become satisfied due to the overabundance of wildebeest veal.

The birth of new-born wildebeest is a sighting that borders on the unbelievable. Remarkably, just after the wildebeest cow drops her calf, it is able to gain coordination and is up on its feet within minutes; not witnessed with other ungulates. The calf is able to run with the herd and even outrun a predator just after 5 minutes of being born. Having said this, there are a great number of calves that unfortunately perish within their first year due to predation, but mainly malnutrition, disease, or fatigue. When the large herds panic, something that happens often, there are also those that sadly get separated from their mothers, and also when crossing the treacherous rivers that come in their path.

The mighty move begins

Around March, the short grassy plains of the southernmost Serengeti start to dry out and the ‘short dry season’ starts coming to an end. It is during this period that the wildebeest continue (or begin) their move towards the western woodlands, dictated mainly by their response to the weather and the growth of new grass that comes with the rains. Hundreds and thousands of years of natural selection and inbred knowledge also account for how and why these ungulates know in which direction they must travel.

The herds begin to move westward from the Olduvai plains towards lakes Ndutu, Masek and Lagarja in their heightened need for water. With there still being short grass, one is able to see the herds scattered widely and feeding across the plains. It is unpredictable how long they will remain spread out across the expansive plains of west Ndutu, but by now the ‘long rains’ start to pour down with wildebeest cantering across the plains against a backdrop of thunder and lightning.

The furrow

The herds begin to move north-west, after the rains have set in, past the Simba and Moru koppies and into the woodlands west of Serona towards Lake Victoria. During this period, the herds merge on the plains and in the woodlands of the Serengeti Western Corridor and, in just short of a month, half a million cows have mated. The full moon in May/June marks the height of this period and it is known for being the best time for those interested in viewing the most action. It is also during this time that the dominant and territorial males tussle in highly energetic duels, but it is ultimately the female who chooses her adequate mate.

The river crossing

Following the rains, the herds begin to head north from the western Serenegeti and into Kenya and the Masai Mara Game Reserve. During this move, the wildebeest are faced with several rivers; the Mbalangeti and Grumeti River in the Serengeti, and the Mara River in Kenya. At this time the rivers are highly flooded, making them treacherous and infested with crocodiles.

Nothing will stop the wildebeest from reaching the abundant succulent grass readily available around the western Masai Mara; they must cross or risk starvation. However, the wildebeest have an inherent instinct to trek in a particular direction, despite their terror and at any cost. Watching the herds crossing these rivers is an unmatched experience, where the wildebeest are met and faced with immediate hostility by the crocodiles and it is a sighting that clearly vindicates nature’s survival of the fittest.

Prey to predators

At the end of the crossing, the banks of both the Grumeti and Mara Rivers are strewn with carcasses and those maimed do not survive the predators of the Masai Mara. The herds spend several months on the grasslands of the Masai Mara, moving from the western side towards the eastern boundaries; feeding once more on the scattered green pastures and taking advantage of isolated rainstorms. Migrating due to the major influence and need for food, makes their constant move a benefit in that they are able to outmarch thousands of hungry predators. Most predators are highly territorial and thus, are not able to follow the herds very far or they have dependant young.

The end to a beginning

Come October, the succulent grass in the Mara is finished and the migrating herds head south for the Serengeti as the first of the ‘short rains’ start falling on the short-grass plains. The wildebeest move down through the eastern woodlands of the Serengeti, with the majority of the cows heavy with their new young. Once the herds have passed the wooded country, they then spread out and scatter once they reach the open plains; where carving will take place and the entire circle begins again.