How Wolves Change Rivers
Wolves were once native to the US’ Yellowstone National Park – until hunting wiped them out. But when, in 1995, the wolves began to come back (thanks to an aggressive management program), something interesting happened: the rest of the park began to find a new, more healthful balance and the most remarkable “trophic cascade” occurred. What is a trophic cascade and how exactly do wolves change rivers? George Monbiot explains in this movie remix.
NOTE: There are “elk” pictured in this video when the narrator is referring to “deer.” This is because the narrator is British and the British word for “elk” is “red deer” or “deer” for short. The scientific report this is based on refers to elk so we wanted to be accurate with the truth of the story. 
Defenders of Wildlife, founded in 1947, is a major national conservation organization focused solely on wildlife and habitat conservation and the safeguarding of biodiversity.
We believe in the inherent value of wildlife and the natural world, and their approach is direct and straightforward – protect and restore imperiled species throughout North America by transforming policies and institutions and promoting innovative solutions.
