SALMON, Idaho (Reuters) - Grizzly bears in and around Yellowstone National Park will be stripped of Endangered Species Act safeguards this summer, U.S. Interior Secretary Ryan Zinke announced on Thursday in a move conservation groups vowed to challenge in court.
Dropping federal protection of Yellowstone's grizzlies, formally proposed in March 2016 under the Obama administration, was based on the agency's findings that the bears' numbers have rebounded sufficiently in recent decades.
The estimated tally of grizzlies in the greater Yellowstone region, encompassing parts of Wyoming, Montana and Idaho, has grown to roughly 700 today, up from as few as 136 bears in 1975 when they were formally listed as a threatened species through the lower 48 states.
At that time, the grizzly had been hunted, trapped and poisoned to near extinction. Its current population well exceeds the government's minimum recovery goal of 500 animals in the region.
Lifting the bears' protected status will open them to trophy hunting outside the boundaries of Yellowstone park as grizzly oversight is turned over to state wildlife managers in Wyoming, Montana and Idaho.
Ranchers, who make up a powerful political constituency in Western states, have strongly advocated delisting grizzlies, arguing the bears' growing numbers pose a threat to humans and livestock. Agitation for state management of grizzlies has also come from hunters, who highly prize them as trophy animals.
Environmentalists say that while grizzlies have made a comeback, their recovery could falter without federal safeguards. They point to the fact that a key food source for the bears, whitebark pine nuts, may be on the decline from climate change.
"The grizzly fight is on. We'll stop any attempt to delist Yellowstone's grizzlies," the Oregon-based Western Environmental Law Center said in a Twitter post.
"We anticipate going to court to challenge this premature, deeply concerning decision," said Bethany Cotton, wildlife program director for the conservation group WildEarth Guardians.
Native American tribes, which revere the grizzly, also have opposed stripping the bear of federal protection.
Zinke, a former Montana congressman, said the final delisting rule by the U.S. Fish and Wildlife Service will be published "in coming days" and go into effect 30 days later.
He hailed the move as marking "one of America's great conservation successes."
Population studies show grizzly bears have more than doubled their range since the mid-1970s, occupying more than 22,500 square miles (58,275 sq km) of the Yellowstone ecosystem, according to the Fish and Wildlife Service. That area is larger than the land mass of New Hampshire, Massachusetts and Rhode Island, combined, the agency said.
Despite those gains, the grizzly is found in only about 2 percent of its original range in the lower 48 states.
For the Yellowstone region, the scope and quality of bear habitat, regulatory mechanisms developed over the years and the existing balance of male and female bears should allow the states to maintain a viable, long-term grizzly population number in the high-600s to low-700s, agency officials said in March when delisting was proposed.
Yelowstone's grizzlies were briefly removed from protected status in 2007 but were re-listed after environmentalists sued, asserting the government had failed to account for such factors as climate change.
A joint federal-state committee of wildlife manager recommended de-listing again in 2012.
The rule will not affect four other smaller federally protected grizzly populations in parts of Montana, Idaho and Washington state. A much larger population in Alaska remains unlisted.
Reporting by Laura Zuckerman in Salmon, Idaho; Additional reporting by Steve Gorman in Los Angeles; Editing by Lisa Shumaker and Sandra Maler