When animal biologists reintroduced wolves to Yellowstone National Park in the ’90s after an absence of about 70 years, a curious thing happened.
The environment changed dramatically – and for the better – in just a few years. Aspen, willow and cottonwood, which the overpopulated deer had grazed on, began a resurgence, thanks to the influence of the wolves. Due to the increased tree cover, migratory birds returned in droves, and other wildlife populations also rebounded. Even more amazingly, Yellowstone’s watershed underwent a positive transformation. This film remix from Sustainable Man, via Films for Action, explains it all in under five minutes.