BOISE, Idaho (AP) — The U.S. Forest Service says it's investigating after Idaho officials reported inadvertently putting tracking collars on four wolves during recent helicopter flights into a central Idaho wilderness restricted to putting collars on elk.

Idaho Department of Fish and Game Deputy Director Ed Schriever in a statement Wednesday says the agency didn't clearly communicate to one of the helicopter crews. Schriever says the agency will refine its procedures so the mistake isn't repeated. Forest Service spokesman Wade Muehlhof says the wolf collaring was not part of the agreement and the federal agency considers it a serious violation.

Three environmental groups sued last week to stop the helicopter flights into the wilderness. Attorney Tim Presso with Earthjustice says Fish and Game could use the tracking collars to kill the wolves.