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.

Geographic variation iri body size and sexual dimorphism, as determined by measurements of condylo-basal length, was investigated in the sugar glider (Petaurus breviceps) and the squirrel glider (P. norfolcensis). Correlation and multiple regression analyses were employed to determine whether geographic or climatic variables accounted for more of this size variation. The effects of age and sex were removed from analyses prior to applying statistical techniques. Numerous geographic and climatic variables were correlated with size variation in both species. Both species followed a clinal change in body size consistent with Bergmann's rule (i.e. both species were larger in the south of their ranges where temperatures are colder). One geographic variable, latitude, and three climatic variables representing temperature, precipitation and seasonality, were then selected for multiple regression analyses. Latitude accounted for more of this size variation (20-28%) in P. breviceps than climatic variables in four multiple regression models (considering two age and two sex classes). This result indicated that an isolation-by-distance model was operating in this species which was attributed to the oceanic barriers between the Australian mainland and New Guinea and Tasmania, causing genetic differentiation between isolated populations. Once latitude was removed from the analyses, temperature accounted for more of the variation (18-24%) in body size in three regressions, whilst precipitation (11%) contributed significantly to the remaining model. This result was interpreted as an adaptation to ambient temperature following Bergmann's rule. When using both geographic and climatic variables, latitude accounted for more size variation (47-69%) than climatic variables in two regressions for P. norfolcensis, whilst seasonality accounted for more variation (26-46%) in the remaining two regressions. When latitude was excluded From the analyses, seasonality (body size decreases with increasing seasonality) accounted for more variation in size in three of four regressions (26-46%), whilst precipitation (60%) accounted for the most variation in the fourth regression. These findings for P. norfolcensis suggested that large body size may be an advantage in aseasonal environments where climates and therefore foods are less predictable. Latitude and precipitation both contributed significantly to the degree of sexual dimorphism exhibited across the range of P. breviceps, suggesting that an isolation-by-distance model and primary productivity account for some of the change in sexual dimorphism in this species. Both these variables were more important than temperature and average sexual dimorphism was greater in the tropics. The relationship with primary productivity implies that in areas where food is more abundant, males attempt to grow larger in order to enhance fighting ability for access to food and mates. In contrast, females channel extra energy towards offspring production, not body size, in order to minimise energy costs during reproduction. Character displacement did not appear to influence body size variation in the two Petaurus species.

In this study, we examined the number of captures and radio-locations of sugar gliders (Petaurus breviceps) necessary to give reasonable estimates of home ranges. Using home ranges determined by radiotelemetry (RTHR) as a standard, we compared nine methods of estimating trap home range (THR) from grid-based mark-recapture data. Correlation analysis was employed to determine which method of estimating THR most closely correlated with RTHRs. A minimum of 12 captures appears to be adequate for reasonable long-term THR estimates derived from the harmonic mean measure (HMM, 50% isopleth). When RTHRs were estimated by either the minimum convex polygon method (MCP) or the HMM (95% isopleth) from loci collected every 30min, a minimum of 36 radio-locations was adequate. Mean RTHR estimates for identical data sets were 53 775m*2 and 35 333m*2 calculated from the MCP and the HMM (95% isopleth) respectively. A number of methods for analysing grid-trapping data produced THR estimates that were significantly correlated with RTHR estimates. Correlations were highest when RTHRs were estimated with the HMM as opposed to the MCP. RTHR estimates derived from the MCP were most strongly correlated with THR estimates derived by the minimum area method, HMM (50% isopleth) and observed range circle (r*2>0.48). When RTHR estimates were derived from the HMM (95% isopleth), the same correlations were higher (r*2>0.88) and THRs estimated by the boundary-strip methods and the adjusted range circle were also highly correlated (r*2>0.65). The significance of the correlations suggests that reasonable short-term THR estimates may be obtained from small capture samples by these above-mentioned methods of calculation. The HMM appeared to exhibit the greatest overall utility, with both radio-tracking and grid-trapping data. The success of the HMM in describing home range appears to be in its ability to depict centres of activity. The technique is most appropriate for animals such as sugar gliders which use concentrated but patchily distributed food resources, and consequently display uneven patterns of use of space.

The diet of the yellow-bellied glider (Petaurus australis) was examined at a site in north Queensland by extensive observation of individuals from 10 glider groups. The diet was assessed in four seasons over 12 months by collating large numbers of qualitative feeding observations and by analysis of faeces. Data were also collected on flowering and bark shedding in the forest. Sap feeding accounted for more than 80% of the feeding observations throughout the year. Nectar and pollen of eucalypts (Eucalyptus spp.) and banksias (Banksia spp.) accounted for much of the remainder of the diet although arthropods and honeydew were present in spring and summer. Faecal analysis was based on much smaller sample sizes but confirmed the qualitative result obtained from direct observations. It also revealed the presence of a wide variety of pollen types. Many of these could be attributed to incidental ingestion but at least six rain forest genera were moderately common in faeces, which is consistent with observations of brief and infrequent visits by gliders to these trees. Examination of eucalypt, banksia and other pollen types showed that 60-70% of pollen was devoid of cell contents, supporting earlier suggestions that gliders obtained protein from pollen digestion, but at this site also from harvesting arthropods. This study confirms the dependence of the yellow-bellied glider in north Queensland on the sap of the red stringybark (Eucalyptus resinifera) and that conservation of the yellow-bellied glider is intimately associated with the management of this tree species. The use of various species for nectar and pollen suggests that the yellow-bellied glider may be an important pollinator in these forests. Moreover, sap from the wounds created by gliders is used by a range of other animal species. These observations suggest that the yellow-bellied glider is likely to be a keystone species in the open-forest ecosystems of north Queensland and that it deserves special emphasis in management.