Mountain lions revitalize ecosystem near San Francisco
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Researchers at Stanford University discovered that increased visits from mountain lions to Jasper Ridge Biological Preserve, a small area 45 miles south of San Francisco, triggered changes throughout the local ecosystem.
From 2015 to 2020, cameras recorded more frequent mountain lion activity, allowing scientists to compare the preserve to earlier periods with less puma presence. They found that as mountain lions became more common, deer became less active, and young oak trees flourished because deer were no longer eating them.
This effect extended to other animals as well. Coyote and bobcat activity decreased, potentially because they avoided the larger predators, while fox activity increased, possibly due to fewer coyotes and bobcats. Researchers call these linked effects “trophic cascades,” where a predator’s presence influences species lower in the food chain. While changes in plant and small predator populations require further study, the impact on deer, coyotes, and bobcats was clear.
The study showed that even small preserves, like Jasper Ridge, can support these complex ecological relationships when connected to larger wilderness areas such as the Santa Cruz Mountains. About 82% of protected land in the United States covers less than two square miles, meaning these smaller areas could be crucial for maintaining biodiversity as cities grow. Elizabeth Hadly, a senior author of the study, noted that humans also influence animal behavior, representing the “ultimate predator” on most landscapes.
