Amur tiger urine increases mesopredators predatory behavior

Apex predators exert dual effects on mesopredators, including both suppression through lethal encounters and fear, as well as facilitation through food provisioning. While large-scale studies on spatial and temporal niche relationships among predators are abundant, research on how apex predators influence mesopredator foraging behavior and the resulting cascading effects on other species, such as ground-nesting birds, remains limited. Using Amur tiger urine as an apex predator cue and captive bird eggs, we evaluated cascading effects in northeastern China. Our results demonstrate that tiger urine attracted small-bodied mesopredators, increasing their visitation speed and accelerating nest predation. Asian badgers in particular perceived tiger urine as a food resource cue, stimulating their exploration and squat-marking behavior improving egg detection and predation. These findings reveal that apex predators can intensify mesopredator predation pressure on ground-nesting birds, challenging the traditional paradigm that apex predators universally suppress mesopredators to benefit lower trophic levels. This study underscores the complex, context-dependent nature of predator-mediated interactions and highlights the need to consider cascading effects in ecosystem management and apex predator reintroduction efforts. By elucidating the dual-edged role of apex predators, this study advances our understanding of trophic cascades and provides critical insights for biodiversity conservation strategies.