DIET OF FERAL HOUSE CATS FELIS-CATUS, FERRETS MUSTELA-FURO AND STOATSMUSTELA-ERMINEA IN GRASSLAND SURROUNDING YELLOW-EYED PENGUIN MEGADYPTES-ANTIPODES BREEDING AREAS, SOUTH ISLAND, NEW-ZEALAND

Spring and summer diets of feral house cats (Felis catus), ferrets (Mu stela furo) and stoats (M. erminea) were studied in grassland surround ing breeding areas of yellow-eyed penguins (Megadyptes antipodes), a r egionally threatened native species. All three predator species ate la rge numbers of young rabbits (Oryctolagus cuniculus) and birds. Stoats also relied heavily on mice (Mus musculus). Use of rabbits increased in rank order of increasing predator size, and male stoats ate more la gomorphs than female stoats. Diet differences may reflect character di splacement as a result of exploitation competition. but interference c ompetition or predation may force the smaller species to exploit micro -habitats with increased ground cover and consequent increased availab ility of smaller prey. Reduction of predation of native species like y ellow-eyed penguins by decreasing or increasing staple mammal prey num bers of the introduced predators may provide lasting conservation bene fits, but could also trigger diet changes that increase risk to endang ered wildlife.