Timber wolves are top predators that were reintroduced amidst controversy to central Idaho in the mid-1990s to restore ecosystem stability. The wolves have since expanded their range and established packs in most of Boise National Forest. Wolves and mountain lions are the forest's top large mammal predators and have no predators of their own except humans. Most of the forest's native mammal species are present in the forest, with the exception of grizzly bears, which have become locally extinct, and plans for their reintroduction to central Idaho have been proposed since the 1990s but have not progressed.