 Gray 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 . 
