Mammal Community Responses to Increasing Puma Activity in a Suburban Preserve.
Sonawane C, Leempoel K, Nova N, Meyer JM, Hébert T
Urban Ecology
The shrubs and young trees struggling to establish in your local nature preserve may depend on a predator nobody sees — mountain lions suppress deer browsing pressure, and without that fear effect, woody plants lose ground to repeated grazing.
Scientists tracked mountain lions, deer, coyotes, foxes, and plant growth in a preserve surrounded by suburbs near San Francisco. As mountain lions became more active, deer and smaller predators changed when they moved around — shifting away from nighttime hours, apparently to avoid running into a puma. Over the same period, woody plants grew denser, likely because deer were too cautious to browse as freely as before. It's an early sign that city-edge wild areas can still function ecologically when a large predator is in the mix.
Key Findings
Statistical analysis confirmed that increasing puma activity over 9 years drove measurable changes in prey (deer, brush rabbits) and mesopredator (bobcat, coyote, grey fox) activity levels in a suburban preserve.
Prey and mesopredators decreased nocturnal behavior across the study period, suggesting they shifted their schedules to avoid temporal overlap with pumas.
Woody plant density increased across three vegetation surveys spanning 17 years in parallel with rising puma activity, providing preliminary evidence of a predator-driven trophic cascade.
chevron_right Technical Summary
As mountain lion activity grew over nine years in a suburban Bay Area nature preserve, deer and other animals shifted their behavior — and woody plants became measurably denser — suggesting large predators can still trigger ecological chain reactions even in landscapes next to neighborhoods.
Abstract Preview
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 troph...
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