A retrospective look at mountain lion populations in California (1906-2018)

Mountain lion (Puma concolor) population management in California has varied widely over the past 100 plus years, ranging from a bounty system (1906-1963) to specially-protected status (1972-present). To elucidate how these different management approaches have influenced California's mountain lion populations, we estimated historical population trends by combining purposeful (i.e., bounty and depredation) and incidental (i.e., vehicle strike) mortality statistics with estimates of annual growth and mortality rates derived from the literature. We used a backwards population projection method to estimate annual abundance and population trends, starting with population sizes drawn randomly from a uniform distribution ranging from 1,000-5,000. These back-calculations suggest that the bounty was effective at reducing mountain lion populations, as all simulations indicated a statewide population decline during this period. Specially-protected status was also likely effective, as mountain lion populations appear to have increased statewide following cessation of the bounty period. These analyses demonstrate the effectiveness of various management approaches to influence mountain lion population trends for the intended results, and provide context for understanding historical aspects of mountain lion populations in California, which is unique from other areas given the species' specially-protected status here.