A long-term study has documented how increased mountain lion activity transformed wildlife behavior and plant growth at a small suburban preserve near San Francisco. Researchers recorded the changes through camera traps and vegetation surveys conducted between 2015 and 2020.
Mountain lions appeared more often on trail cameras at Stanford's Jasper Ridge Biological Preserve during the study period. Deer activity declined sharply compared with earlier years when the big cats were rarely seen.
Woody plants favored by deer, including young oak trees, showed clear signs of recovery. Smaller predators such as coyotes and bobcats were recorded less frequently, while fox activity increased.
The findings, published in Ecology and Evolution, illustrate a trophic cascade in an area of limited size. Lead author Chinmay Sonawane noted that such effects are possible when small preserves connect to larger wilderness areas like the Santa Cruz Mountains.
Researchers caution that some lower-level changes may also reflect shifts in fog or temperature. Evidence for direct links between mountain lions and deer, coyote, and bobcat behavior remained strongest.