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Aquatic Ecosystems Affected by Wildebeest Migrations in Kenya

Herd mentality takes over as wildebeests migrate across river
Chris Dutton
Cary Institute of Ecosystem Studies
A crowded wildebeest river crossing on the Mara River, Kenya

Researchers have found that the Serengeti Wildebeest play a surprising and significant role in aquatic systems in the Mara River Basin of Kenya.

“The Serengeti wildebeest migration is estimated at about 1.3 million individuals," said Dr. Amanda Subalusky, an aquatic ecologist with the Cary Institute of Ecosystem Studies in New York and visiting researcher at Utah State University. "It migrates up from southern Serengeti where they breed to the northern Serengeti during the dry season for feeding and it is considered the largest overland migration in the world.”


Subalusky said this migration is one of a handful that is almost entirely within the boundaries of a protected area. She believes the preservation of their migratory route has helped protect the population from diminishing or disappearing altogether like many other large terrestrial species.


“There are estimates that there were 30 to 60 million bison in the American West as recently as the late 1700’s,” she said.


The preservation of the migratory route has helped the area retain significant ecosystem functions associated with moving across large rivers, including the drowning of many wildebeests. As a result of mass drownings, many nutrients are flooded into the rivers and further down the food chain.


“To actually see a drowning happen, and we’ve witnessed a few, is a heart-wrenching experience," she said, "but what we see is the river and animal inhabitants of the river respond in quite a different way to these events so it really brings the river to life. Within a day or so of a drowning happening, you’ll start to see all kinds of avian scavengers come into the area. You’ll see crocodiles and Nile monitors basking along the carcasses and feeding on them, you can see fish coming up from underneath and feeding. You know everything really makes great use of this resource.”


Researchers speculate mass drownings are not a new phenomena and have been contributing regularly to ecosystem functions throughout history. However, conflicting land use interests and migratory patterns have made studying large migration patterns more difficult in the modern era.