Mammal Community Responses to Increasing Puma Activity in a Suburban Preserve.

Predators can shape ecosystems by directly reducing prey abundance and inducing fear-driven changes in the behaviour of their prey and mesopredators, with potential cascading effects on lower trophic levels. However, these effects have been studied in landscapes with relatively low human presence. While some predator species coexist with people in human-dominated landscapes, it remains unclear whether predators can fulfil their prey regulation functions in such environments. In a suburban preserve in the San Francisco Bay Area, USA, puma activity increased over nine years. We investigated if this increasing puma activity affected mesopredators (bobcats, coyotes and grey foxes), prey (black-tailed deer and brush rabbits) and woody plants at a local scale using evidence from three analyses. First, convergent cross mapping analysis indicated that pumas influenced longitudinal changes in prey and mesopredator activity. Second, daily activity pattern analysis showed that prey and mesopredators decreased nocturnality, potentially to avoid pumas. Third, limited plant community sampling (three surveys during a 17-year period) revealed that woody plant density increased as puma activity increased. Collectively, these analyses provided corroborating, preliminary signals that increasing puma activity coincided with changes in bobcats, coyotes and deer. However, inferences about any effects on foxes, rabbits and woody plants remain provisional and warrant stronger empirical confirmation. Nonetheless, as humans and predators increasingly overlap spatially, ensuring that large predators can persist and function ecologically in human-dominated landscapes is a growing conservation priority.