Estimated 34–42 (across all age and sex classes) on the northern range from most recent surveys; others in park seasonally.

As of early 2026, wildlife biologists estimate the cougar population in Yellowstone National Park to be roughly 25 to 45 resident animals. These elusive predators, also known as mountain lions, primarily inhabit the northern range of the park, which provides the rugged, rocky terrain and high prey density (such as elk and mule deer) they prefer. Cougars are notoriously difficult to count because they are solitary, nocturnal, and highly territorial, often covering vast home ranges that can extend beyond the park boundaries. The Yellowstone Cougar Project uses GPS collars and DNA analysis from "scat" and hair samples to track the population. While their numbers fluctuate based on prey availability and competition with the park's thriving wolf and grizzly bear populations, the current count is considered a stable and healthy representation of a top-tier predator in a balanced ecosystem. Despite their presence, cougars are very reclusive; sightings by park visitors are extremely rare, as these cats go to great lengths to avoid human interaction.