Response of small mammals to site characteristics in the northern midlands of Tasmania

Small mammals have certain requirements for survival, for example, shelter and food. Shelter is an important resource for small mammals as it can protect them from predation and environmental factors. Shelter also has the potential to supply mammals with sufficient material for nesting and cover. Food is essential for survival and provides energy for day to day activities and reproduction. A trapping study was employed to consider the relationship of the presence and abundance of three mammal groups; (1) small native mammals (irrespective of species), (2) arboreal mammals (here Trichosurus vulpecula) and (3) small native ground-dwelling mammals (Bettongia gaimardi, Isoodon obesulus, Perameles gunnii and Potorous tridactylus), with three shelter characteristics; (1) vegetation patch size, (2) overall vegetation patch complexity and the (3) vegetation structure within a patch. The study was conducted on 30 selected sites in an intensive agricultural area in the Northern Midlands of Tasmania. Vegetation patch size and overall patch complexity were found to affect significantly the presence and abundance of total small native mammals (positive association). Arboreal mammals were significantly affected by overall complexity only (positive association) and were predominately found in sites with vegetation patches consisting of a high canopy, ground and litter cover. Ground-dwelling mammals were significantly associated with increasing vegetation patch size, with similar vegetation characteristics to arboreal mammals, including high canopy, ground and litter cover. An alternative method to trapping was also used to detect bandicoot presence and abundance, a ground-dwelling mammal of particular interest, to four habitat variables; (1) vegetation patch size, (2) overall vegetation patch complexity, (3) vegetation structure within a patch (as well as gorse specifically) and ( 4) food biomass. This method was the recording of diggings, which is a characteristic of bandicoot foraging behaviour. Digging counts were made along transects established at the 30 sites used in the mammal trapping study. Bandicoots were found to be significantly associated with both patch size and overall complexity (positive association). The structure of the vegetation typical of bandicoots appeared to be high canopy, ground and litter cover. As for the presence of bandicoot diggings and gorse, results indicated that gorse was more important to bandicoots than no ground cover at all; however, diggings were even more likely at sites with ground cover but no gorse. There was a marginal effect of food biomass on the presence of bandicoot diggings.