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BILLINGS, Mont. — Wildlife advocates and a Montana Indian tribe have asked a U.S. court to restore protections for grizzly bears in and around Yellowstone National Park so that trophy hunting of the fearsome animals would not be allowed.

The Northern Cheyenne Tribe, the Humane Society and several conservation groups filed three lawsuits Tuesday and Wednesday in federal court in Montana, challenging the government's recent move to lift protections.

Idaho, Montana and Wyoming are planning limited public hunting of the region's roughly 700 bears, although no hunts are expected this year.

Related: Feds Remove Grizzly Bears From Protected List

Critics say there is already too much pressure on the bear population as climate change affects what they eat and as conflicts with humans result in dozens being killed every year.

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A separate challenge of the government's decision was filed in July by Native Americans from seven states and Canada. They say hunting for the bruins goes against their religious and spiritual beliefs.

A Department of Interior spokeswoman referred questions on the lawsuits to the Department of Justice, where officials did not immediately respond to requests for comment.

This is the second time the U.S. Fish and Wildlife Service has lifted protections for grizzlies in the Yellowstone region — 19,000 square miles (49,210 square kilometers) of forested mountains, remote valleys and numerous small towns.

The bears lost their threatened status in 2007, only to have it restored two years later by U.S. District Judge Donald Molloy.

A grizzly bear walks along Yellowstone Lake in Yellowstone National Park in 2013. Marc Cooke / AP file

Molloy said federal officials had failed to demonstrate that bears could adapt to the loss of a key food source, the nuts of the whitebark pine tree, which scientists say has been decimated by climate change.

Since that ruling, government biologists have done further research to show bears can shift to eating more meat, such as elk.

Related: Senate Votes to Overturn Obama-Era Hunting Limits in Alaska

But an attorney for the Northern Cheyenne Tribe, Sierra Club and other conservation groups said the biologists' finding ignored the increased likelihood that bears seeking elk will come into conflict with hunters and other people.

"The result is we're finding more dead bears," attorney Tim Preso said. "Things have worsened (since 2009) in that the mortality of the population has really dramatically increased."

Government biologists from the U.S. Geological Survey say the region's grizzly population has stabilized after several decades of steep growth. They were first placed under Endangered Species Act protections in 1975.