Diel activity of free-ranging cats and their mammalian and avian prey on the oceanic Madeira Island, Macaronesia

Abstract

Species’ activity patterns offer insights into overall behaviour as well as intra- and inter-species interactions. In multiply invaded systems, synergistic interactions between invasive species can contribute to the decline of native fauna. We conducted a protected area-wide camera trap survey to investigate the diel activity patterns of invasive free-ranging cats and their overlap with both native and non-native prey on the Macaronesian island of Madeira, Portugal. Free-ranging cats showed greater temporal overlap with non-native mammalian prey than with native and non-native birds. Specifically, cats exhibited the highest coefficient of temporal overlap with rabbits, followed by rodents, passerines, and lastly partridges. This suggests that non-native prey, including rabbits and partridges (both alien game species in Madeira), may be subsidising cat populations, potentially leading to hyperpredation of native prey. Our results highlight the need for evidence-based management of free-ranging cat populations and a reconsideration of practices associated with the restocking of alien game species.