Population ecology of the squirrel glider (Petaurus norfolcensis) and the sugar glider (P. breviceps) (Maruspialia : Petauridae) at Limeburners Creek, on the central north coast of New South Wales

Abstract

The population ecology of the squirrel glider (Petaurus norfolcensis) and the sugar glider (P. breviceps) was studied at Limeburners Creek Nature Reserve, on the central north coast of New South Wales. The study was undertaken between July 1986 and November 1988. Sugar and squirrel gliders at Limeburners Creek exhibited similar home-range sizes (2.54 ha) despite considerable differences in mean mass between the species (squirrel glider 192-213 g; sugar glider, 104-119 g). Squirrel gliders existed at higher densities (049-1.54 ha-') than did sugar gliders (0.24454 ha-') and populations of both species exhibited male-biased sex ratios. The timing of births was not consistent between years and, at least in the squirrel glider, occurred in almost all months of the year over the 2.5-year study. Usually a winter peak in births that extended into spring was apparent, sometimes following an autumn peak. Mean litter size for both species (1.8-1.9) was similar to that recorded for the sugar glider in Victoria. Most adult females of both species exhibited the capacity to raise two litters in a year. Hence, natality rates (2.3-2.4 young per year) at Limeburners Creek were high relative to those recorded for the sugar glider in Victoria. Recruit persistence time (3.0-3.5 seasons) was similar between the species and recruitment appeared to be most successful during years when heavy eucalypt and Banksia flowering was recorded. Populations of both species were characterised by high rates of juvenile dispersal and mortality. Young gliders dispersed at a mean age of 10.9 and 12.5 months in the sugar glider and the squirrel glider, respecti~e1y;SquirreI gliders nested in colonies of 2-Bindividuals. Usually at least one male and two females nested together, suggesting a polygynous mating strategy. The mating system of the sugar glider at Limebumers Creek was less clear, but colonies appeared to comprise at least monogamous pairs with or without a surplus of males. Sugar glider colonies at Limebumers Creek varied in size from two to seven individuals. The larger squirrel gliders were clearly dominant to the smaller sugar gliders in interspecific behavioural interactions. Inconsistencies in body-weight fluctuations between years for both species were thought to be a consequence of the unpredictable nature of the aseasonal, coastal climates and resulting food resource abundances.