The cougar (puma, mountain lion) was nearly or completely absent from the Waterton Park area when the park was created. Unregulated hunting, low numbers of prey species, and an aggressive predator control policy combined to keep numbers low through the early part of the century. Sporadic predator control continued within Waterton Park until the late 1960's.
The solitary and elusive cougar is now seen more frequently as populations gradually recover. The townsite and campgrounds, with their habituated deer and sheep, have become a favourite hunting ground for some cougars, especially in the quiet fall and winter seasons. Cougar attacks on humans are rare. There have been two incidents within Waterton Lakes National Park in the last decade where a child received minor injuries. Females with kittens and animals which are cornered, surprised or feeding on a kill may act aggressively. Cougars often show curiosity toward human activities without behaving aggressively.