Efficient detection techniques will confirm the presence of a species at a site where the species exists, and are essential for effective population monitoring and for assessing the outcome of management programmes. However, detection techniques vary in their ability to detect different species. A wide range of mammalian predator species, most introduced into New Zealand since the late 18th century, have had a detrimental impact on the native flora and fauna.
The introduced brushtail possum (Trichosurus vulpecula) is a major environmental and agricultural pest in New Zealand but little information is available on the ecology of possums in drylands, which cover c. 19% of the country. Here, we describe a temporal snapshot of the diet and feeding preferences of possums in a dryland habitat in New Zealand's South Island, as well as movement patterns and survival rates. We also briefly explore spatial patterns in capture rates. We trapped 279 possums at an average capture rate of 9 possums per 100 trap nights.
We collated 48 surveys of individually banded birds or birds fitted with radio transmitters that were checked before and after 1080 poison (sodium fluoroacetate) baits were aerially distributed to control brushtail possums (Trichosurus vulpecula) in New Zealand forests. The surveys were associated with 34 pest control operations from 1986 to 2009 and covered 13 native bird species, of which four were kiwi (Apteryx spp.). Sample sizes ranged from 1 to 46 birds (median 15). In 12 cases a sample of 1 to 42 birds (median 13) was surveyed in an untreated area at the same time.
Browsing by introduced brushtail possums is linked to major declines in mistletoe abundance in New Zealand, yet in some areas mistletoes persist, apparently unaffected by the presence of possums. To determine the cause of this spatial variation in impact I investigated the abundance and condition (crown dieback and extent of possum browse) of two mistletoes (Alepis flavida, Peraxilla tetrapetala) and abundance and diet of possums in two mountain beech (Nothofagus solandri var. cliffortioides) forests in the central-eastern South Island of New Zealand.
Himalayan thar or tahr (Hemitragus jemlahicus), Alpine chamois (Rupicapra rupicapra) and brushtail possums (Trichosurus vulpecula) are native to the Himalaya, Europe and Australia, respectively, but are now sympatric in parts of the central Southern Alps, New Zealand. All three species are managed as pests by the Department of Conservation. We analysed the diets of 246 thar, 78 chamois and 113 possums collected in the central Southern Alps during 1988–1996.