Here is my logic. The original population was thought to top out at around 100 wolves, this may be true in normal conditions. When animals have the proper resources their populations will grow. There has to be some factor that limits their population expansion (space/food/predation/disease). In this case Yellowstone contains an abundant food source for the wolves and also no hunting of wolves. So basically the rate of fitness for these critters is very high because they are getting plenty of food and are able to reproduce. If they don't make some type of effort to control the wolf population they will do it to themselves. Eventually they will depleat their food resources enough and many will die off. Wolf Killer the ticks are a mooses worst predator here in saskatchewan.