Safari in the Serengeti, discovering a fascinating ecosystem.

A vast line appears on the horizon, wildebeest meandering in the distance. An Ariadne's thread that stretches as far as the eye can see, the herds are entering migration and can be more than 40 kilometres long. For thousands of years, the wildebeest have criss-crossed the Serengeti with the seasons in search of new pastures and fresh water to drink.

These great migrations have become rare, since most African mammals have ceased their great journeys. The human population explosion is to blame. In spite of themselves, this is undermining the survival of their habitat. The Serengeti is one of the few unspoilt places in the world where you can still witness these remarkable migrations. The park's ecosystem is one of the most productive in the world and has been functioning for thousands of years. And while the scenes of predation you may witness may seem violent, don't forget that the animals are all interdependent and that this is the cycle of life.

Some would say that wildebeests are stupid and strange-looking. Masai legend has it that "he was given the head of a warthog, the neck of a buffalo, the stripes of a zebra and the tail of a giraffe". This myth is often embellished by a version that says he has the brain of a flea. However, the reality is quite different, and the wildebeest is one of the most important animals on African soil. From a demographic point of view, there are between 1 and 2 million of them in the Serengeti, making it the most common species in the park. As far as the appearance of their bodies is concerned, every part is the fruit of evolution. Each adaptation now enables them to cover enormous distances during their migrations. These migrations are essential to the survival of the species and the park's ecosystem as a whole.

The great distances they cover during their migrations benefit the entire Serengeti ecosystem. Thanks to their flat snout, for example, they can graze an impressive mass of grass. While their sloping hindquarters help them to walk more smoothly and save the energy they need to cover these long distances. Scientists have noticed that, over time, fires in the park have become rarer. This is due to the wildebeest herds that keep the grass short. This considerably reduces the risk of fire due to drought. These fewer fires also allow trees to grow and create forests. And more trees mean more insects, birds and herbivorous animals that feed on leaves, such as elephants and giraffes. In addition, by travelling long distances, wildebeest help to fertilise the soil, which in turn produces more food for other animals.

The wildebeest uses a surprising strategy to ensure the survival of its species. Unlike other herbivores, females give birth in broad daylight and do not hide their young. Lions and other predators tend to hunt at dusk, so this strategy makes the young wildebeest less vulnerable. Almost all the mothers in the group deliver their offspring at the same time. In the space of a few days, no fewer than 500,000 young are born (around 24,000 a day). This is the ideal time for predators to come into play, on the lookout for their next feast. Because they are all born together, the wildebeest population is too large for the lions and other hyenas, leopards and cheetahs to feast on. As a result, losses compared to births are minimal. In the space of two months, wildebeest herds have increased in size by almost a third. And as you will have realised, more wildebeest means more food for predators. The more wildebeest there are, the more food they provide for other animals in the savannah.

Eager for a king's feast, the predators - crocodiles and big cats - wait patiently for the herd of over a million animals to appear on the horizon. After tirelessly roaming the arid lands of the park, the wildebeest's most formidable test looms along the Kenyan border: crossing the Masai Mara River. One after the other, they set off at a good pace to finally reach the grazing area waiting for them on the other side. In indescribable chaos, you watch as the weakest and youngest are trampled to death down the steep bank leading to the river. Afterwards, many of them drown in the rough and tumultuous waters of the Masai Mara River, while others are seized by impatient and hungry crocodiles.

You may witness predation scenes of rare savage intensity. However, drowning is the most serious threat to wildebeest. Thousands die during these crossings. And, even if crocodiles and other birds of prey relish the meal. The decomposing bodies of wildebeest provide essential nutrients for the rivers of the Serengeti. The wildebeest carcasses thus make a major contribution to the park's ecosystem. It takes almost 7 years for the animal remains to be completely absorbed by the river. Over time, a "biofilm" develops on the carcasses, serving as food for the fish.