Short-term influence of snow cover on movements and habitat use by brushtail possums (Trichosurus vulpecula)

Climatic events affect the behaviour and ecology of many mammal species (e.g. activity, body condition, home range sizes or predation risk within others). We investigated short-term changes in movements, activity and habitat use of brushtail possums (Trichosurus vulpecula) in response to two major snowfall events in a grassland ecosystem in the southern South Island of New Zealand during winter of 2011. Global positioning system collars were deployed on 21 possums. Generalised linear mixed models showed that, on average, possums reduced their movements and activity (measured by distances between consecutive fixes) during periods of snow cover. One hundred percent minimum convex polygon areas decreased by 37% on average, and 95% and 50% kernel density contour ranges decreased by 34% and 36%, respectively. Two to three possums (depending on the snowfall event) actually increased their movements during snow cover. No dramatic changes in habitat use were observed during the study but rock habitats were used slightly more often during snow periods, probably because rocks provide warmer and drier shelters during harsh weather conditions. Our study illustrates the behaviour of possums in seasonally harsh conditions outside their native range.