Trophic roles of black rats and seabird impacts on tropical islands: Mesopredator release or hyperpredation?

摘要: Rats contribute to the decline of tropical seabird populations by affecting their breeding success through direct predation eggs and chicks. When they coexist with other predators, invasive rats may also generate indirect interactions via changes impose on structure communities trophic following invasion (‘hyperpredation process’), or when apex predators are eradicated from ecosystem (‘mesopredator release effect’). Understanding these effects is necessary implement restoration operations that actually benefit threatened populations. We investigated processes two French islands western Indian Ocean, Europa Juan de Nova, where black different predator species (introduced cats potentially native barn owls). The parallel use several methods (diet analysis, stable isotopes, monitoring) identify roles revealed impact seabirds was particularly high only owls occur, consumption chicks resulting in low for species. suggested hyperpredation associated top-down regulation occurring although territoriality buffer this process. Conversely we found evidence mesopredator effect unlikely, irrespective identity. Considering most likely both provided recommendations eradication priorities mitigate risk local extinction currently facing.