This study investigated several aspects of the biology of the marsupial squirrel glider, Petaurus norfolcensis, in three southeast Queensland populations and presents notes on the sugar glider, P. breviceps, which occurred with P. norfolcensis at one study site. A general introduction to the study is provided in Chapter One.
The primary aim of the project was to investigate sociality, mating systems and male dominance hierarchies through collection and analysis of observational, endocrinological and genetic data. As the project developed however, it became evident that a system for distinguishing between the closely related P. norfolcensis and P. breviceps would be required. Results of numerical taxonomic investigations, presented in Chapter Two, revealed that the most consistently useful characteristics for distinguishing between the two species are width of fur at the base of the tail, head length, the ratio between width of fur at the base of the tail and width of the flesh at the base of the tail. Length of the left hindfoot and the ratio between head length and head width are also useful, but to a lesser extent. Discriminant functions were generated for use in future classification of species.
Chapter Three describes the isolation and characterisation of microsatellite loci for use in studies of sociality in natural populations. A total of seven loci were identified, although one showed strong and consistent deviation from Hardy-Weinberg equilibrium and high frequency of null alleles and was consequently excluded from further analyses. Polymerase chain reaction primers were also trialled in P. breviceps and P. gracilis (the Mahogany Glider) using samples collected in a previous study of northern Queensland populations. Four loci proved useful in these species. Preliminary population genetic analyses demonstrate that all species and populations are genetically differentiated.
Chapter Four presents summary reproductive data from the southeast Queensland P. norfolcensis populations, with brief notes on P. breviceps. Reproduction shows a seasonal pattern, with peak numbers of pouch young recorded in late autumn and winter. Declines in oestrogen concentrations outside of the breeding periods indicate that females are anoestrous in the summer months. The majority of reproductive females (83%) captured during the study were in the 2-3 year age category, but all individuals over one year of age were found to have bred. Average litter size across all populations was 1. 73±0.01 (n=23). Male scrotal diameter and testosterone concentrations showed no significant seasonal variation. It is suggested that this is due to the presence of both socially dominant and subordinate males in the data set. Maximum testosterone concentrations did coincide with periods of mating. Condition index showed no relationship with reproductive variables, but it is likely that this results from flaws in the statistical generation of the index. Previous studies have suggested that competition for mates results in sexual dimorphism in polygynous petaurids. The results of this study indicate that these factors are less important in P. norfolcensis.
Studies of sociality and male dominance hierarchies are presented in Chapter Five. While individuals were observed to nest together on a regular basis, spotlighting and nestwatching observations and genetic data suggest that social group composition is neither static nor easily defined. Evidence that males form dominance hierarchies was collected, but dominant status did not confer increased paternity rates. Genetic data demonstrate that females mate with multiple males and multiple paternity is common within litters. Both male and female young were more likely to disperse than be recruited into the natal group, but there is some evidence that females may occasionally remain within the natal group. The overall pattern of mating is random. Results are discussed in broader context in Chapter Six.