The Serengeti Great Migration Part 2 - Rutting Season and the push north

By Julian 01 July 2017

An introduction to The Great Migration’s rutting season and their migration north

For the entirety of the wet season, our young wildebeest has spent the first few months of its life in the Serengeti’s short grass plains. Getting stronger daily due to its mothers nutritionally rich milk from mineral rich grass, our calf is oblivious to the fact that it faces one of the greatest challenges known to a young animal – a 600km Great Migration – in the first few months of its life. The short grass plains it will now leave behind are where it would not survive if it stayed. The Serengeti’s short grass plains in the dry season are an arid, lethal place.

The herds will leave their wet season short grass plains when the rainwater pans dry up, possibly even before the grass has stopped growing. I’ve heard some guides say that the parasite load can also force the herds to move north, however the fact remains that in April or early May, for a possible number of different reasons, the herds start their big migration north.

Historically the herds move northwest towards the western corridor before they move to their dry season grazing grounds of the northern Serengeti and the Maasai Mara National Reserve. This is backed up by the satellite data we have, which clearly indicates a move to the western corridor. However not all wildebeest follow this route. Many head up through the heart of Seronera in the central Serengeti whilst some guides claim that every year they will see good numbers moving up the eastern boundary and even through Loliondo itself to the east of the Serengeti.

Where is the Great Migration located and why?

If the herds were to follow the Serengeti’s rainfall then moving directly north, following green grasses and eventually ending up in their dry season grazing grounds of the Maasai Mara and northern Serengeti would be the right move. However over 50% of the herds will move out to the western corridor, where another area of incredibly nutritious soil and grass awaits them. The ‘mega herds’ move along the Mbalageti and Grumeti river systems whilst others literally mow the vast plains between the two rivers – Musabi, Kirawira and Sabora for example.

Many years ago a shift in the plates below the Serengeti caused a natural barrier that blocked the rivers and created a number of lakes along with Lake Victoria itself. The result, over the years is alluvial deposits that have in time created incredibly rich soil and grass – possibly the finest in the entire eco-system. The black cotton soil in the area however is something the herds avoid until the plains dry out…hence why there are so few wildebeest in the area from December through to April and early May, even when there is good rain.

The western corridor is also the location for the first river crossings over the Grumeti river. At this time of year however, much of the Grumeti river is little more than a trickle, with the occasional hippo filled pool and crocodile infested shallow stream. The big river crossings we have all seen on National Geographic documentaries happen later in the year, on the Mara river from the end of June onwards.

April and May into June is also the heart of the wildebeest rutting season, when males fight for dominance and the Serengeti’s migration is one big amorous affair! It is a remarkably noisy and remarkably violent…but fascinating time of year as patches of prime grazing are fought over by testosterone pumped bulls.

The movement of the Great Migration is different every year!

In a dry year, the first herds will have left the western corridor and will be reaching the northern Serengeti by late June. In a wet year, due to how good the grazing is in the central/western/Lobo parts of the Serengeti, the herds will take another month to settle into the ‘north’. In a very good year, when grazing is plentiful the herds will spread out from just north of the central Serengeti all the way up into the Maasai Mara; a vast area that just shows the sheer scale of the herds.

I would advise clients to be careful of travelling to the northern Serengeti in late June. The length of grasses can be an issue (cats spend most daylight hours lying down!) and historically the mega herds settle into the northern parts of the park and the Maasai Mara itself in late July.

It is also worth mentioning that the quality of the grasses here can keep good numbers of the Great Migration in the west of the Serengeti for longer than many people think. I’ve personally witnessed huge herds in the areas north of the western corridor, officially outside the park in the Grumeti Reserves and also Ikorongo in August – blowing the myth out of the water that the herds head all head swiftly north and have no reason to hang around in the western corridor.