DAILY ACTIVITY OF STOATS (MUSTELA-ERMINEA), FERAL FERRETS (MUSTELA-FURO) AND FERAL HOUSE-CATS (FELIS-CATUS) IN COASTAL GRASSLAND, OTAGO-PENINSULA, NEW-ZEALAND

This radio-tracking study reports the daily activity rhythms in autumn and spring of 11 stoats (Mustela erminea) (9 male, 2 female), 20 ferr ets (M.furo) (8 m, 12 f) and 11 feral house cats (Felis catus) (7 m, 4 f) resident on coastal grassland, Otago Peninsula, New Zealand. Activ ity rhythms differed markedly amongst individual stoats in autumn, but little amongst individual cats and ferrets in either season. Stoats w ere equally active day and night in autumn, but were more active at da y than at night in spring. Cats showed moderate day activity, but were mainly active at night in both seasons. Ferrets showed low activity d uring daylight in autumn and were entirely nocturnal in spring. Overal l, stoats were more active during daylight than cats or ferrets; and c ats were more active during daylight than ferrets. Therefore, cats and especially stoats may pose the main predation threat to diurnal nativ e species in New Zealand. Effective biological control of rabbits (Ory ctolagus cuniculus) may effect the absolute abundance and daily activi ty of the predators, so is impossible to predict the overall impact of predation on diurnal and nocturnal native species.