An integrated dietary assessment increases feeding event detection in an urban carnivore

Abstract

Urbanisation radically changes habitats and alters available resources. Populations of large, highly mobile species are often extirpated at the urban-wildland interface, while species like mesocarnivores may thrive by capitalising on changes in prey abundance. We investigated the diet of the caracal (Caracal caracal), a medium-sized felid inhabiting patchy natural habitat isolated within the dense urban matrix of South Africa’s second largest city, Cape Town. We systematically integrated two classic dietary methods (scat and GPS clusters) by accounting for gut transit times. As part of a larger caracal ecology study, we GPS-collared 26 individuals over a two-year period (2014–2016) to generate coarse (3-hour) and fine-scale (20-minute) GPS movement data. Using the movement data, we investigated 677 GPS-clusters for prey remains. We collected 654 scats, half of which were found at GPS-clusters and were linked with the individual sampled. By systematically correcting for a range of gut transit times, we determined whether scat at cluster sites was from the same or an earlier feeding event, thereby increasing the overall detection of feeding events by > 50%. Avian prey dominated GPS cluster findings while micromammals were overwhelmingly represented in scat. Although > 40% of feeding events occurred within 200 meters of the urban edge, caracals largely preyed on native species. Our findings have implications for understanding the ability of some species to persist in the face of rapid environmental change, human-wildlife conflict, pathogen transmission, and bioaccumulation of pesticides. Further, this approach could be incorporated into studies that estimate foraging-explicit resource selection and habitat preference.