In 379 logged areas comprising a total of 5606 ha, 930 individuals were found representing 7 species of glider and opossum. However, at 199 sites (52% of the forest area) no arboreal marsupials were found. About 63% of the individuals came from 9% of the area. From author's summary.
The relationships were examined between measurements of forest habitat (10 explanatory variables: X) and densities of three species of arboreal marsupials (greater glider, feathertail glider and sugar glider); the sum of these three and an additional five species that occurred; species richness and diversity of all eight species present in the area (six response variables: Y). The habitat variables were: landform profile; elapsed time since a severe fire; degree of forest maturity (total basal area of wood); an index of den tree density; ratio of number of regeneration size trees to den trees; floristic diversity; basal area of peppermints; basal area of gums; basal area of eucalypts with a low level of nutrients in their foliage; and an index of potassium concentration in the foliage. The principal component transformation of the X set of variables (PCA) was used as an aid to interpret the individual response of Y to joint intercorrelated explanatory variables X. The regressions of Y on PCA-transformed X explained 76.2% of variation in density for the greater glider, 50.4% for the feathertail glider, 21.1% for the sugar glider, 68.3% for all arboreal marsupials, 49.7% for species richness and 30.1% for species diversity. The weak regressions obtained for densities for the sugar glider were attributed to probable non-measurement of important understorey habitat variables for this species, and those for species richness and diversity, to the presence of a curvilinear rather than linear relationship to foliage nutrients. The gradient in foliage nutrient concentration appears to be the major determinant of the density and species richness and diversity of arboreal marsupials in the Eden forests. Exceptions to the trend seem to occur where the forests include certain xeromorphic eucalypt species that are high in foliage nutrients yet poor in fauna, and, for the feathertail and sugar glider, in those sections of the Eden forests exhibiting fire successional stages and that are usually composed of eucalypts with low nutrient levels in their foliage.
We examined the relationships between abundance of 16 species of waterbirds and the rainfall in eastern Australia, the rainfall west of this region, the annual Southern Oscillation index (SOI), the wetland area, and hunting in eastern Australia for the period 1983–92. Data were collected during aerial surveys of eastern Australia. For most explanatory variables, lags of up to five years before aerial surveys were also investigated during these analyses. The analyses covered all nine game species (plumed whistling-duck, Australian shelduck, Australian wood duck, pink-eared duck, grey teal, chestnut teal, Pacific black duck, Australasian shoveler, hardhead) and seven non-game species (Australian pelican, white-faced heron, yellow-billed spoonbill, freckled duck, black swan, black-winged stilt, red-necked avocet). Regression models were developed for all species apart from Australian pelicans. Rainfall and climate indices generally were most correlated with the species' abundance. Bonferroni adjustments to significance levels meant that there were significant variables in regression models for seven of the 16 species. Abundance indices for plumed whistling-duck, chestnut teal, hardhead, black swan and black-winged stilt were related to the climate variables (rainfall, SOI) and wetland area, whereas abundance of pink-eared duck and red-necked avocets were negatively related. Abundance of chestnut teal was positively related to numbers of hunting licences sold. The results are equivocal about the role of hunting in determining waterfowl abundance, which is probably a reflection of few data points and numbers of variables included. In general, abundance indices of waterbirds appear to have decreased between 1983 and 1992, which may correspond to other factors not modelled
