brushtail possum

Transects at right angles to the shoreline are used to describe seven herbaceous, two scrub and four forest communities of the lake edge. Composition, structure, site preference and relation to lake level are given for these communities. The effect of browsing mammals on the flora and structure of mountain beech forest is shown by comparison of forest on Buncrana Island with that on the adjacent mainland. Shoreline vegetation is compared with that recorded from other areas in Fiordland.

Agouti grey pelage, as found in the opossum and many other mammals, is a generalised concealing coloration. In dense vegetation melanic pelage also is concealing, but the melanic phase displaces the grey one in rain forests where, in the current absence of predation, selection is not for colour. This local dominance suggests close linkage of genes for melanism with ones for toleration of humidity.

We quantified brushtail possum (Trichosurus vulpecula) diet in a mixed Nothofagus fusca-N. menziesii forest in north Westland. Diet comprised 49 food items of which four (Aristotelia serrata, Muehlenbeckia australis and Weinmannia racemosa foliage, and W. racemosa flowers) contributed 68%. The canopy dominant Nothofagus species were a minor diet component (<1%), while wood, fungi and bark were a small but consistent part of diet (10.1%).

Poisonous baits used for pest control in New Zealand commonly contain green dye and cinnamon oil to make them less attractive to birds. Research aimed at reducing the impact of poison based pest control on birds has shown that some birds are initially deterred from feeding on blue or, to a lesser extent, green coloured food and are attracted to yellow or red food. We determined whether colours that deter or attract birds affected the acceptance of non-toxic and toxic cereal baits by captive brushtail possums (Trichosurus vulpecula).

Two techniques for assessing possum (Trichosurus vulpecula Kerr) diet from stomach contents ("point-sampling" and "layer- separation") are described and compared. Point-sampling involves sieving stomach contents, systematically selecting fragments from the retained material then, identifying and weighing these. Layer-separation involves separation, identification, and weighing of the discrete layers apparent in most possum stomach contents. In 41 of 43 stomachs examined, we were able to separate discrete layers that nearly always comprised a single food item.

Possum leaf diet from 1976 to 1989 in the Orongorongo Valley was compared with the diet recorded from four previous years, using faecal analysis. There were large differences in the proportions of species eaten in different seasons and between different years. There was little overall change in the proportion of the main diet tree species, Metrosideros robusta and Weinmannia racemosa, and seasonal increases or declines in one were usually balanced by opposite changes in the other.

Bird populations were monitored for one year (October 1990- October 1991) to determine whether the 1080 poison used to eradicate possums and wallabies on Rangitoto Island had had any detrimental effects on them. There was no significant decline in bird numbers recorded immediately after poisoning, with four species increasing in abundance (P <0.001). Twelve months after the operation the abundance of four species had increased significantly (P <0.001).

Two morphological types of brushtail possum (Trichosurus vulpecula) were introduced to New Zealand: smaller, grey possums from mainland southeastern Australia, and larger, black possums from Tasmania. Analysis of patterns of allozyme variation and allele frequencies of present-day possum populations in New Zealand and southeastern Australia indicates that populations comprised predominantly of black possums remain genetically similar to possums in Tasmania, whereas predominantly grey populations are genetically closer to Victorian and New South Wales possums.

The diet of brushtail possums (Trichosurus vulpecula Kerr) in mixed hardwood forests on a central Westland hillside is described from analysis of plant cuticle fragments and seeds in their faeces. Faeces were collected monthly for 2.25 years from animals live-trapped from low altitude forest/ pasture margins through to high altitude alpine shrublands. The diet included forest and pasture foliage, buds, and fruits of over 100 species, although most were eaten infrequently.

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.