Ecological changes linked to wolves
Ten years ago today, the first of eight travel-weary wolves stepped out of its cage and into Yellowstone National Park.
Those steps -- the first known wolf prints in Yellowstone in decades -- created ecological and social currents that are changing the landscape in parts of Montana, Idaho and Wyoming.
The return of one of the region's top predators, now numbering up to 900, may be altering everything from elk behavior to tree growth to beaver populations. Ranchers manage their livestock differently, and some face wrenching losses. Hunters now pursue wolf-spooked elk.
The changes offer a glimpse of what the future may hold for parts of Washington, where it's only a matter of time before wolves take up residence, biologists say.
Oregon State University forester Bill Ripple went to Yellowstone National Park in 1997 looking for an answer to the decline in aspen groves there. He emerged with a surprising answer: wolves.
A study of growth rings on the trees showed that the youngest dated to the 1920s, around the time when wolves were eradicated from the park. Ripple hypothesized that the disappearance of the predators emboldened elk, which then ate young, tasty trees with impunity.
He and a colleague followed up with research that found similar age patterns in cottonwood trees, and evidence that willows have had a resurgence in recent years.
"As soon as we get rid of wolves, plants stop flourishing. Soon after we bring wolves back, plants are flourishing again," Ripple said.
If true, it shows how wolves can influence a broad web of plants and animals. Beaver rely on willows for food and songbirds live in aspens and willows, so their populations might rebound. Animals that thrive around beaver dams could get a boost. Already, a part of the park now hosts nine beaver colonies where there was one when the wolves first arrived, said Douglas Smith, the lead wolf researcher at Yellowstone National Park.
The wolf's arrival also has coincided with a 50 percent drop in coyote populations, Smith said. That could help red foxes, which are killed by coyotes. It also could increase populations of rodents eaten by coyotes, a potential boon for hawks that prey on mice.
"We've grown accustomed to what the world looks like without top-level carnivores. Here you've got a place where they're all present, and it looks real different," he said.
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Ecological changes linked to wolves