Intraspecific and seasonal differences in the diet of feral ferrets (Mustela furo) in a pastoral habitat, east Otago, New Zealand

This study reports the diet of feral ferrets (Mustela furo) in a pastoral h abitat, East Otago, South Island, New Zealand. Rabbits (Oryctolagus cunicul us) were the most common prey of ferrets, occurring in 86.7% of seats, but birds (12.4%) and invertebrates (11.3%) were also frequently eaten. Female ferrets ate more non-lagomorph prey items, especially invertebrates and bir ds than males. No significant dietary differences were found between juveni le and adult ferrets except in summer when juveniles ate more lagomorph pre y. There were seasonal differences in the consumption of rabbits, invertebr ates, skinks, possums (Trichosurus vulpecula) and small and large secondary prey items. Seasonal differences in ferret diet are likely to be related t o the relative abundance of the various prey items. Lagomorph availability may also be a determinant of the frequency of occurrence of other prey item s in the diet. Dietary differences may differentially influence the functio nal response of adults and juveniles and/or males and females to rabbit con trol or other manipulations of prey populations. Bovine tuberculosis (Mycob acterium bovis) infections in ferret populations show intraspecific variati on with more males than females and more adults than juveniles infected. In traspecific dietary differences in diet were not observed in the species (p ossums and hedgehogs (Erinaceus europaeus)) considered to be the main sourc es of infection for ferrets.