BOISE, Idaho (AP) -- Six environmental groups have joined a federal lawsuit against the U.S. Forest Service over whether the state can land helicopters in a roadless area to collar wolves.

The groups are asking a judge to temporarily stop Idaho's plans to fly helicopters into the Frank Church River of No Return Wilderness to aerially dart and collar wolves. The groups, which include the Western Watersheds Project, The Wilderness Society, Great Old Broads for Wilderness and the Idaho Conservation League, contend the state's use of helicopters violates a 1964 law that created backcountry preserves.

The use of motorized travel isn't normally allowed in wilderness areas. But Idaho officials say trapping wolves from the ground isn't effective, so they want to do it while they're flying over the wilderness on deer and elk counts.

Copyright 2010 The AP.