Identification of terrestrial predators at two Little Penguin colonies in South Australia

Abstract

Identifying predators and determining their influence on bird population declines can be crucial in the implementation of appropriate conservation measures. In this study, we focus on the Little Penguin Eudyptula minor , a flightless seabird whose numbers have seriously declined in some populations across Australia and New Zealand, for a variety of reasons, some not fully understood. Using a combination of motion-camera monitoring at active burrows and postmortem examinations of carcasses, we present data on the identity, occurrence and impact of terrestrial predators at two colonies in South Australia: Granite Island and Emu Bay (Kangaroo Island). Terrestrial predation varied from 20% for carcasses found on Granite Island to 44% at Emu Bay. There was no evidence for predation at burrows on Granite Island but, at Emu Bay, we identified goannas (Heath Monitor Varanus rosenbergi) as predators of chicks (by using cameras), and Cats Felis catus as predators of chicks and juveniles (from postmortem examination of carcasses). In addition, 45% of the carcasses found at Emu Bay were categorised as chicks. We discuss potential biases in identifying causes of death from carcasses only and the importance of combining both direct and indirect evidence.