Cascading Effects of Apex Predator Recovery on Rodent Foraging Activity and Seed Predation

Abstract

Apex predators can trigger trophic cascades that shape plant–animal interactions. By suppressing medium-sized carnivores, apex predators may indirectly influence small prey behavior and abundance, altering key ecosystem functions such as post-dispersal seed predation. We investigated cascading effects of the Iberian lynx (Lynx pardinus) on rodent foraging activity and predation of Pyrus bourgaeana seeds in southern Spain, comparing sites with lynx presence and absence (low vs. high mesopredator abundance, respectively). We deployed 1152 seeds at 144 seed depots and used 36 camera traps to monitor rodent activity and foraging. We analyzed how predation risk, habitat, and microhabitat influenced (1) seed predation, (2) seed encounter probability, (3) number of visits to seed depots, and (4) visit duration. Seed predation rates were unaffected by lynx presence (57% vs. 43%), but this apex predator altered multiple aspects of rodent foraging activity. Seed encounter probability was 88% greater with lynx absent. In lynx presence, non-consumptive visits in forest habitats were 83% greater and visit duration rose 59-fold compared to lynx absence. The number of visits to seed depots was 85% greater with lynx present, but shrub microhabitats received more visits with lynx absent. Rodent abundance positively affected the number of visits and seed predation but did not vary with lynx presence. These behavioral changes in post-dispersal seed predation may ultimately affect seed dispersal success and thereby plant recruitment. Our findings underscore the role of apex predators in modulating ecosystem functions via non-lethal pathways and the importance of behaviorally mediated trophic cascades for plant–animal interactions.