Predator identification from bite marks on penguin and albatross chicks

Abstract

Ferrets Mustela furo, Stoats M. erminea and feral House Cats Felis catus are introduced predators in New Zealand that threaten many nesting seabirds and other native species. Fifty-one Yellow-eyed Penguin Megadyptes antipodes chicks, four Royal Albatross Diomedea epomophora chicks and one Little Penguin Eudyptula minor adult underwent necropsy. Four Yellow-eyed Penguin chicks, three Royal Albatross chicks and the Little Penguin had puncture holes in their skin from predator bites. Three Royal Albatross chicks also had markings on their bills that were analysed separately. Only three outlying puncture hole pairs could be matched unequivocally with the species-specific inter-canine distance of each predator species. Most bites were clustered so that separate bites could not be discerned. One Yellow-eyed Penguin chick and two Royal Albatross chicks were preyed on by Stoats, but the culprits responsible for the deaths of the other 21 dead birds could not be definitely determined. There are many logistical problems and unquantified assumptions in other methods of identifying predators and in several unquantified claims that predator identity is known. Development of better diagnostics to identify predators would help conservation management by allowing better targeting of predator trapping and poisoning efforts.