Cats of all types are about as stealthy animal as you will find. There is a lot of territory in those mountains. Heck, some soul goes hiking and gets lost. They send out all kinds of folks looking for someone who is not particularly trying to stay unseen, and they still cannot find them even with some idea of where they are. Now imagine an animal that moves as quiet as fog, and is largely nocturnal. I think it is highly possible.