ABSTRACT
Absence of apex predators simplifies food chains, leading to trophic degradation of ecosystems and diminution of the services they provide1. However, most predators do not coexist well with humans, which has resulted in a decline of carnivores and functional ecosystems worldwide2. In some instances, cryptic carnivores manage to survive amidst human settlements, finding refuge in small biological islands surrounded by urban landscapes. In such a system, we used two non-invasive data collection methods (camera trapping and fecal sampling) to investigate the multiannual relationship between predators and prey, and between competitors, through analysis of: (1) relative abundance and detection probability of species over time, (2) causal interactions via empirical dynamic modeling, (3) diet, and (4) diel activity patterns. All approaches show concordance in the results: the natural return of an apex predator, the puma (Puma concolor), triggered a trophic cascade, affecting the abundance and behavior of its main prey, subordinate predators and other prey in the studied system. Our study demonstrates that trophic recovery can occur rapidly following the return of a top predator, even in small protected areas in increasingly urbanized landscapes.
