Trail-camera data from 2015 to 2020 at Stanford's 1,193-acre Jasper Ridge reserve showed mountain lions appearing more often — and increasingly in daylight — as researchers documented a trophic cascade.
Deer activity fell during the same period, and surveys found recovery in woody plants such as young oaks that deer commonly browse, pointing to top-down ecological effects.
Coyote and bobcat activity also declined as puma presence rose, while fox activity increased, fitting an "ecology of fear" pattern in which smaller predators shift behavior to avoid a larger one.
Stanford researchers said the links to deer, coyotes and bobcats were strongest, while lower-level effects on vegetation, foxes and rabbits remain tentative because environmental factors may also have played a role.
The study argues that small suburban preserves connected to larger wilderness can still support fully functioning food webs, even as the reason pumas expanded into Jasper Ridge remains unclear.