KENYA, 2016

A herd of wildebeest as they cross the Mara River during migration


© Reuters / Thomas Mukoya

One of the largest migrations in the world takes place in Africa. At the end of the rainy season, when food starts to become scarce, more than a million wildebeest (Connochaetes taurinus) travel from Tanzania’s Serengeti National Park to Kenya’s Maasai Mara Reserve in search of more fertile land. Like all journeys, this migration encounters obstacles, such as the difficult crossing of the Mara River. The strong currents and presence of lurking crocodiles and hippos present a real challenge and some 6,000 of the migrating ungulates lose their lives in these waters every year.
A recent US study found that these mass drownings act as a genuine “fuel” for the ecosystem. The biomass of these thousands of drowned wildebeest is the equivalent of ten decaying blue whales, providing food for numerous species. The same study clearly shows the way in which a migration of land animals can have a major impact on a river ecosystem and how the drownings can affect nutrient cycling and food webs for decades. A change in this system can completely alter it, with unknown consequences. The current predominantly anthropogenic climate change is one of the most serious threats to many migrants, as it alters the cycle of the seasons on which they depend. In a world where we are all connected and where the action of one has consequences for many, we need to be aware of our actions so we can limit climate change and safeguard migrants and their ecosystems.

Martina Lando