stoat

We studied the ecology of a high-density population of stoats in Fiordland, New Zealand, in the summer and autumn of 1990-91 following a Nothofagus seeding in 1990. Results are compared with findings from the same area in 1991-92, a period of lower stoat density. In the high-density year, minimum home ranges (revealed by radio-tracking) of four females averaged 69 ha and those of three males 93 ha; range lengths averaged 1.3 km and 2.5 km respectively. Neither difference was statistically significant.

Home range and diet of stoats inhabiting beech forest were examined by trapping and radio-tracking. Eleven stoats (6 female, 5 male) were fitted with radio-transmitters. Minimum home ranges of five females averaged 124 ± 21 ha and of four males 206 ± 73 ha. Range lengths of females averaged 2.3 ± 0.3 km and of males 4.0 ± 0.9 km. These differences were not statistically significant. Adult female stoats appeared to have mutually exclusive home ranges. Two females and one male had home ranges that were bisected by the Eglinton River.

The abundance and diet of stoats (Mustela erminea) were compared before and after an aerial 1080-poison operation for possums (Trichosurus vulpecula) in a New Zealand podocarp- hardwood forest. Poisoning dramatically reduced ship rat (Rattus rattus) abundance. Although rats were the main prey item of stoats before the poisoning, stoat abundance was unaffected by the operation and there was a change in stoats' diet from rats to birds. The conservation benefits and risks of undertaking such operations are not clear.

The prevalence of infestation of the skulls of stoats with the parasitic nematode Skrjabingylus nasicola was previously described in a national survey by King and Moody (1982). Since then, more samples from Craigieburn Forest Park and from the Eglinton Valley, Fiordland, have been collected, and a method of determining the actual ages of adult stoats has been developed. The extended samples are here examined for a relationship between infestation and age, which could not previously be tested. Prevalence generally increases with age, significantly so at Craigieburn.