Mountain lions (Puma concolor) started appearing with increasing frequency on trail cameras at Stanford’s Jasper Ridge Biological Preserve (‘Ootchamin ‘Ooyakma) from 2015 to 2020. Researchers documented a corresponding drop in deer activity compared to the prior years of lower or absent puma activity. Vegetation surveys also showed that many woody plants deer like to eat or tend to trample, including young oak trees, began to thrive.

These types of multi-level effects, called trophic cascades, have been studied primarily in large wilderness areas, particularly cascades caused by apex predators such as wolves reintroduced into Yellowstone National Park. This research, published in Ecology and Evolution, indicates the effect can be found in smaller preserves as well.