A spectacle of life and death, a hard struggle for survival, an epic journey that is renewed every year: the most impressive migratory phenomenon on planet Earth.
An unparalleled spectacle is repeated every year in a corner of the earth between Kenya and Tanzania. It is undoubtedly the most massive mass shift in the natural world every year.
We are talking about the migration of wildebeest (and, together with them, a large group of ungulates) from the Serengeti National Park, in Tanzania, to the Maasai Mara reserve, in Kenya. A group “move” in search of greener pastures in which to refresh oneself, involving over one million and 600 thousand specimens, chased by a vast corollary of predators.
A long march in search of green pastures
BUT WHAT GOVERNS THE SYNCHRONOUS MOVEMENT OF SO MANY ANIMALS?
The factors that most likely affect the migration patterns of wildebeest and other creatures of the savannah are the abundance of food and water; in particular, the availability of fresh grass in a soil rich in phosphorus, an essential element for the females of this species, especially during the lactation period.
The timing of migration varies considerably from year to year. In general, at the end of the rainy season (which in East Africa falls between May and June) the wildebeest of the Serengeti migrate north, in search of greener pastures and water to drink.
When, a few months later (between October and November) the rains return, the animals return to the south, where they started.
They stay there until February-March, when the puppies are born, and then start moving north again at the end of April. An infinite circle that begins with the birth of the animal and ends only with death.
emotions without equal
Group movement is an established anti-predator technique: moving en masse, wildebeests minimize the chances of ending up in the clutches of lions, hyenas, cheetahs and crocodiles, a bit like fish moving in schools.
Even giving birth in the same period of the year responds to the same need. With so many puppies available, in fact, it will be more unlikely that enemies will catch their own.
For the same reason, the wildebeest do not travel alone, but accompanied by about 200,000 zebras, and 400,000 gazelles and impalas. Some scientific studies have shown that these ungulates also know how to perceive the alarm calls of other animal species (such as, for example, those of baboons) and exploit them to save themselves.
The surplus is not the only weapon that the Serengeti wildebeest have at their disposal. They can also count on a remarkable speed (up to 80 km per hour), strong horns and cunning forms of cooperation, such as alternating shifts of night watch to watch over the rest of the herd.
All these resources come in handy in the most challenging moment of the trip: crossing the Mara River, between Kenya and Tanzania, infested with crocodiles that take advantage of the opportunity of such a large number of prey to stock up on meat.
Reptiles crouched in the river can perceive the vibration of the millions of hooves on the ground well before the ungulates reach the watercourse. Generally, before diving, the herds gather on the banks, and the pack leaders are pushed ahead, forced to throw themselves into the rushing waters of the river.
One of the fundamental imperatives for these herds is to keep the puppies within the group, protecting them with their size. It is estimated that every year in the Serengeti, between February and March, about 500,000 new wildebeest are born: after 45 minutes from birth, the young are already able to run at the same speed as their parents.
the migration from the sky
In an annual migratory journey, a specimen can cover up to 3,000 km of travel. The column of migrating animals can be as long as 40 km.
It is not difficult to imagine the reason that makes the migratory movements of wildebeest so frequent: the food consumption capacity of over a million herbivores puts a strain on the grass regrowth rates. In other words, when a pasture is running low, you need to give it time to sprout again.
The food needs of wildebeest and their trampling play a fundamental role in maintaining the ecosystems of the savannah: the growth of grass is encouraged by their consumption (and their manure, which acts as a fertilizer), and also the upper part of the food chain , constituted by predators, benefits from their passage.
One of the most fascinating facts of this migration? The routes can vary from year to year as well as the times: the movement of the herds is repeated with eternal cyclicality and yet differently every year.
an epic journey
