2016-05-02. After a Comeback, New Challenges for Yellowstone’s Grizzly Bears.

posted May 3, 2016, 10:02 AM by Alan Gould
By Jim Robbins, The New York Times. For GSS Losing Biodiversity chapter 8. Excerpt: YELLOWSTONE NATIONAL PARK, Wyo. — When the Yellowstone grizzly bear was listed as threatened under the Endangered Species Act in 1975, there were only about 100 to 200 of them in the park and the surrounding country. The main culprit in their decline was, oddly, garbage. Bears raiding Dumpsters in a campground ...were often shot as scary nuisances. A 35-year campaign to clean up dumps and bear-proof garbage cans — and to teach people to keep picnic baskets and coolers in the car — has had a significant payoff. There were 717 grizzlies at last count in the 20 million acres in and around Yellowstone National Park. Still, the bears have all but disappeared from almost all of the continental United States, except for Yellowstone and Glacier National Parks and a few other slivers of habitat. All told, there are about 1,800 in the lower 48 states. One reason for the overall decline is that they have the lowest reproductive rate of any mammal in North America, besides humans. Sows have their first cubs at five to eight years of age, and space them three years apart. Just one in three cubs survives to adulthood. A grizzly lives about 30 years on average. Now scientists are at a crossroads: Some biologists say that the grizzlies’ numbers are robust and that it is time to remove the most stringent protections for the bears, “delisting” them under the species act, which among other consequences means they would probably be hunted again for sport. That prospect disturbs even those in favor of lifting the restrictions. Citing the grizzly’s recovery in the wild country in and around Yellowstone, the Fish and Wildlife Service tried to delist the bear in 2007. Environmentalists sued, and a federal court forced officials to redo an analysis of the future of the whitebark pine tree, whose nuts are an important food for the bears. The tree’s numbers have declined widely as the climate in the Rocky Mountains has warmed, and tree-killing insects are taking a steep toll. ...Kerry Gunther, a biologist who heads the bear management program at Yellowstone, says he favors delisting the bear. But although he is a hunter, Dr. Gunther says he cannot imagine shooting a grizzly. “Each bear is an individual,” he said. “They are highly intelligent.”...  http://www.nytimes.com/2016/05/03/science/after-a-comeback-new-challenges-for-yellowstones-grizzly-bears.html