The current population of lions in Yellowstone is estimated to be 18-24 animals and is thought to be increasing. Mountain lions live an average lifespan of about 12 years in the wild. Mountain lions were significantly reduced by predator control measures during the early 20th century.

Yes, Yellowstone National Park was once home to the American lion (Panthera atriox), a massive prehistoric feline that was significantly larger than modern African lions. These predators roamed the region during the Pleistocene epoch and went extinct approximately 11,000 years ago. In more recent history, "lions" in Yellowstone refer to mountain lions (cougars). Mountain lions were nearly extirpated from the park in the early 20th century due to predator control programs but naturally recolonized the area in the late 1970s and 1980s. Today, a stable population of cougars exists within the park, serving as a top-tier predator alongside wolves and bears. They are elusive, solitary animals that primarily hunt elk and deer, maintaining the ecological balance of the Greater Yellowstone Ecosystem. While they are often called "lions," they are taxonomically distinct from the Panthera genus found in Africa and Asia.