File this under another ecological 'duh oh'. Notice how these studies are done after the fact, like after the fact that the Alberta government has allowed commercial expansion into wilderness areas.
Banff food web shows sharp differences without wolves
CBC News
When wolves left an area near Banff, Alberta, elk became more common, a meadow replaced willow trees, and songbirds were replaced by sparrows, biologists say.
In the mid-1980s, wolves naturally recolonized the Bow Valley in Banff National Park, except for areas near the town itself.
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| Gray wolf (CP file photo) |
Mark Hebblewhite of the University of Alberta in Edmonton and his colleagues have found the exclusion of the wolves caused major changes in the area's food chain, down through its trophic levels.
The study in the August issue of the journal Ecology is one of the first large-scale studies to show the key role of a top predator on land.
"Those effects trickled in a cascading fashion down the trophic levels from the highest carnivore to the herbivores, elk, down to vegetation," Hebblewhite said.
Since wolves feed on elk, the number of herbivores jumped without the predators. Elk populations were 10 times as high in the low-wolf area compared to where many wolves roamed, the team found.
"Where there's lot of elk, it's like a lawnmower's gone through and mowed everything down," Hebblewhite said. "There's no young aspen."
Beaver populations, which depend on willow to build their dams, also seemed to decline. Songbirds like the American Redstart also vanished from the area without wolves.
