Who's Afraid of the Big Bad... Elk?
Loss of wolves in a Canadian park led to drastic changes in forest habitat
AFTER A 1950s rabies scare, park wardens at Canada's Banff National Park started shooting gray wolves on sight. By the 1960s, Banff's wolves were gone. Not coincidentally, that's around the time that elk, once a main source of food for the wolves, started to take over. Multiplying herds of elk devoured the native willows, leaving behind far less biodiverse grassland meadows. Twenty years ago, after the wolf eradication policy changed, wolves slowly began returning on their own to the Banff area, attracted by ample food and room to roam. Now a new study claims that the disappearing, reappearing wolves have turned Banff into a perfect illustration of "trophic cascade"--the disastrous effects upon an entire ecosystem of removing a top predator. "You don't need a degree to see it," says Mark Hebblewhite, a researcher from the University of Alberta, one of several institutions involved in the study. "You can see it from the road."
The areas closest to the town of Banff, where wolves are still absent, remain stripped of willows. In more remote areas, where wolves have returned, willow forests have also returned--as have the songbirds and beavers that make their homes among the trees. "The next stage is to restore wildlife corridors and let the wolves re-colonize on their own," says Hebblewhite.