Seven conservation groups are seeking to reverse April’s delisting of grizzly bears in and around Yellowstone National Park, saying the action was premature.

In a lawsuit filed Monday in U.S. District Court in Idaho, the groups claim grizzly bears still face threats to their continued existence, including an isolated population and climate changes that are killing the bear’s main source of food.

“Scientific analyses have shown conclusively that the grizzly bear population in the greater Yellowstone area will not survive as an isolated population,” said Michael Garrity, executive director of the Helena-based Alliance for the Wild Rockies. “Removing (Endangered Species Act) protection from grizzly bears in Yellowstone amounts to a death sentence for these bears.”

But Chris Servheen, the U.S. Fish and Wildlife Service grizzly bear recovery project coordinator, said the population in Yellowstone is “robust and doing well,” growing at a rate of 4 to 7 percent each year for the past 10 years. While he had expected a lawsuit to be filed by the groups, who he termed “professional litigators,” he still was clearly frustrated by the action.

“I’m disappointed. This lawsuit will clearly take all my time away from the bears in Cabinet/Yaak, the Selkirk, the Cascades and the Northern Continental Divide Ecosystem that remain listed,” Servheen said. “Delisting was a biological decision. I’ve been the recovery coordinator for 26 years, and it’s taken this long because we’ve been very meticulous about it.”

Four other distinct grizzly bear populations exist outside of Yellowstone, mainly along the U.S.-Canadian border. Those include about 500 in the Glacier Park/Bob Marshall Wilderness area; 30 to 40 in the Cabinet/Yaak area; 30 to 40 in northern Idaho and northeast Washington; and about five in the North Cascades.

Those remain protected as threatened species under the Endangered Species Act.

The conservation organizations that filed the lawsuit say the various grizzly groups are too small and too isolated for long-term viability, which they believe will require 2,000 to 3,000 bears in linked populations.

“True grizzly bear recovery means reconnecting our current grizzly bear populations and not killing bears that are reclaiming public lands that could link bear populations,” said Jon Marvel of the Western Watersheds Project.

“They were listed as one population — those in the Northern Continental Divide Ecosystem — and we believe they need to be connected before they can be delisted,” Garrity added.

But Servheen counters that geneticists studying the Yellowstone bears say there isn’t any problem with diversity. He acknowledges problems with some of the smaller populations, and notes that the long-term plan calls for an intensive effort to improve and enhance travel corridors.

Other groups involved in the litigation include the Sierra Club, the Natural Resources Defense Council, the Center for Biological Diversity, the Great Bear Foundation and the Jackson Hold Conservation Alliance. They’re being represented by EarthJustice and Advocates for the West.

The groups aren’t seeking an injunction at this point to halt the delisting, but will do so if an “imminent threat to their mortality” is posed — like instituting a hunting season, Garrity said.

Servheen notes that even with delisting, Yellowstone grizzly bear populations will continue to be closely watched. Those duties will be handled inside Yellowstone Park by the National Park Service. Outside the park’s boundaries, management activities will be taken over by state officials.