By Laura Zuckerman
SALMON, Idaho (Reuters) - The return of wolves to Yellowstone National Park may be helping imperiled grizzly bears to survive by keeping elk herds on the move and preventing them from destroying berries that are a staple food for grizzlies, according to a new study.
In the mid-1990s, the U.S. government released fewer than 100 wolves into the park and the wilderness near Salmon, Idaho, to restore an iconic Western animal that had been hunted, trapped and poisoned to near extinction in the Northern Rocky Mountains.
Today, roughly 1,700 wolves roam the Yellowstone border states of Idaho, Montana and Wyoming, where hundreds of the predators have been hunted and killed since being removed in 2011 and 2012 from the federal threatened species list.
Scientists suspected nearly two decades ago but couldn't say with precision that the reintroduction of an apex predator missing from the larger Yellowstone landscape for 70 years would help restore an ecosystem hobbled by overgrazing by elk, bison and cattle.
Research published on Monday in the Journal of Animal Ecology suggests Yellowstone wolves may play a pivotal role if threatened grizzlies are to flourish.
Yellowstone grizzlies showed greater quantities of berries in their scat after the wolves' reintroduction, which has thinned and dispersed elk herds and reduced concentrated foraging that can destroy berry bushes, researchers found.
"What is interesting and surprising here is that we have one large predator affecting another large predator," said Oregon State University ecologist William Ripple, the study's lead author.
OUTCRY OVER HUNTING
The report is one of the first to examine the relationship between the roughly 600 grizzlies in the Yellowstone area and the fewer than 100 wolves that frequent the park. There was a public outcry earlier this year after hunters killed a dozen of those wolves. Hunting is illegal in the park but popular in adjacent states.
Ranchers and hunters want to cut the number of wolves and grizzlies, complaining they prey on livestock and elk. Hunting groups like Rocky Mountain Elk Foundation blame wolf reintroduction for reducing elk numbers in Yellowstone's northern herd area by 80 percent, from an estimated 19,000 to less than 4,000, largely through predation.
Chris Wilmers, environmental science professor at the University of California-Santa Cruz who was not involved in the study, said the new findings add to a growing body of work showing how predators impact Yellowstone.
"You never have an eye on the whole ecosystem and how everything is connected until you see it working," Wilmers said.
Research suggesting wolves indirectly benefit bears comes as federal grizzly managers examine if climate changes will curtail production of whitebark pine nuts, a food crucial for bears trying to bulk up before hibernation.
That question is at the center of a lawsuit brought by conservationists against the U.S. government in 2007 when it sought to lift federal protections from a Yellowstone area grizzly population that U.S. bear managers said have made a healthy comeback from the brink of extinction.
A federal appeals court in 2011 upheld a lower court ruling that left protections in place for Yellowstone grizzlies because the government had discounted the impact of climate changes. An assessment of climate factors is expected in coming months, along with a possible renewed push to remove bears as protected and open the way for hunting.
(Editing by Cynthia Johnston and Grant McCool)