Research overview: the mesopredator release concept in urban ecosystems

Mesopredator release, in which the decline of top predators allows smaller predators to increase and overexploit prey, is a foundational concept linking urban fragmentation to biodiversity loss. This overview synthesises theory and evidence, including the seminal demonstration in fragmented California canyons where losing bobcats and coyotes triggered domestic-cat and fox increases and bird declines. It examines the conditions under which release occurs, its consequences for native prey, and the implications for retaining apex and meso-carnivores in cities. The synthesis frames mesopredator release as a central organising idea for understanding why the structure of the urban predator guild matters for ecosystem health.