Feeding ecology of an invasive predator across an urban land use gradient

Abstract

Urbanisation poses a major threat to biodiversity, often resulting in the local decline or extinction of native species. Urban and peri-urban areas, in general, contain a mosaic of fragmented natural habitats in which native species can find refuge. While, the persistence of native species is often tenuous in such refuges, little is known about how introduced predators, such as the European red fox (Vulpes vulpes), affect native prey in urban environments in Australia.This study aims to address this knowledge gap by assessing the diet composition and morphology of foxes along an urban land use gradient, transecting the Greater Sydney Region, Australia. Diet composition was assessed through measuring the proportion of volume of each prey category in the stomachs of fox carcasses. Morphology was assessed in respect to skeletal measurements, body mass and body condition of those carcasses.Diet composition varied considerably along the gradient, with mammals, birds, insects, plants and anthropogenic food representing significantly different proportions of the foxes' diet in different land use categories. Native mammals were predominantly consumed in non-urban areas, whereas introduced mammals were mainly consumed in urban areas. Nevertheless, urban foxes still consumed a considerable amount of native marsupials, mainly comprising common ringtail possums (Pseudocheirus peregrinus) and common brushtail possums (Trichosurus vulpecula). No threatened species were identified in the diet of foxes in this study. Foxes exploiting anthropogenic food were also heavier and in better condition than foxes without access to this resource supplementation.Thus, foxes are highly opportunistic and adaptable predators of a wide variety of prey in Australian urban environments; however, further research is required to confirm the magnitude of their impacts on native species in urban refugia.

Date of Award	2017
Original language	English