EcoWorldly

25% of all the world’s large-scale terrestrial migrations have already ceased due to habitat loss and human-caused changes to the landscape, and it may not be long before all migrations disappear entirely.

That according to a new study, which warns that with continued population growth, development and habitat encroachment, storied epics like those of wildebeest parading across the Serengeti or herds of bison rumbling across North American plains shall become tall tales of the past.

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The study looked at all 24 species of large ungulates (large-bodied herbivores) known for their mass migrations across all kinds of landscapes, including caribou, bison, elk, zebra, wildebeests, chiru and saiga. North American mass migrations were the most severely endangered, where several species are only still considered migratory by technical definition. For instance, bison used to roam the whole expanse of the Great Plains, but now their migrations are restricted to two small sites in Yellowstone National Park and Alberta, Canada.

The primary driver of large-scale migrations is the search for more abundant food and water. In more temperate landscapes, that availability changes with the seasons, and in more equatorial or savannah landscapes, the availability depends upon following the rains. As humans siphon and control waterflow, fence landscapes and turn grasslands into farmland, mass migrations become impossible.

There are almost no major land routes remaining which aren’t significantly blocked, fenced or developed. Migrations are more than just a necessary aspect of the life cycle for most species, they are essential to their survival and adaptability. Thus, as migrations disappear, the extinctions of migratory species are expected to rapidly follow.

Of course, mass migrations are also crucially fundamental to the balance of whole ecosystems. Since they expand over such vast landscapes, the extinction of mass migrations could have profound and unpredictable results on a scale much larger than the migrations themselves. Undoubtedly, as migratory animals go extinct, so too will countless other species, like Africa’s big cats, which also depend upon sustenance brought via those migrations.

“A large part of this is an awareness issue. People don’t realize what we have and are losing,” says Grant Harris, co-author of the study. “We lose migrations and become biologically depauperate with farms and fences, even though there is no reason why humanity cannot technically and socially advance while maintaining natural phenomena. A balance can be struck—we just need to strike it.”

Image Credit: colinjackson1972 on Flickr under a Creative Commons License

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