[Nestor Chayelle] How Wolves Change Rivers

The Yellowstone case

When wolves were reintroduced to Yellowstone National Park in the United States, after being absent nearly 70 years, the most remarkable "trophic cascade" occurred.

Yellowstone National Park, the first National Park in the world, is home to a myriad of species as well as to pristine Rocky Mountain wilderness. The park straddles Wyoming, Idaho, and Montana and became the first National Park for good reason: its natural beauty draws over three million visitors annually, from every corner of the globe.

A century ago, wolves were not charismatic attractions for visitors to the park. They were a threat to the park’s attractions. “Gray wolves are increasing and have become a decided menace to the herds of elk, deer, mountain sheep, and antelope,” warns the 1915 superintendent’s annual report.

 “Several were killed in the park last winter, and an effort will be made the coming winter to capture or kill them.”

They were successful, the wolves were eradicated from Yellowstone Park.

What is a trophic cascade and how exactly do wolves change rivers? George Monbiot explains in this movie remix.

Almost a century later wolves were reintroduced to the park (1995) and this happened…

This may be one of the most important conservation concepts to come out of natural science in the last half-century. The thing about this case study is that the same can be applied to apex predators around the world: lions in Africa, tigers in Asia. Sharks, bears and wild dogs are all species sitting at the top of their respective food chains, creating stability amongst the species they prey on and maintaining the health of plants and animals right down the ladder.

"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." - John Muir

Maybe Yellowstone will be our own lesson on humility.

- Nestor Chayelle