Population ecology of the eastern pygmy-possum (Cercartetus nanus) in a montane woodland in southern New South Wales

The population dynamics of nectar-feeding non-flying mammals are poorly documented. We investigated aspects of the population ecology of the eastern pygmy-possum (Cercartetus nanus) in southern New South Wales. We captured 65 individuals over a 4-year period during 5045 trap-nights and 1179 nest-box checks. The body mass of adult males (mean +/- s.e. = 24.6 +/- 1.0 g) was marginally not significantly different (P = 0.08) from that of non-parous adult females (28.2 +/- 1.9 g). Females gave birth to a single litter each year of 3-4 young during February-May. No juveniles were detected in spring of any year. Mark-recapture modelling suggested that survival probability was constant over time (0.78) while recapture probability (0.04-0.81) varied with season and trap effort. The local population (estimated at similar to 20-25 individuals) underwent a regular seasonal variation in abundance, with a decline in spring coinciding with the cessation of flowering by Banksia. A population trough in spring has been observed elsewhere. This appears to represent some local migration from the study area, suggesting a strategy of high mobility to track floral resources. Conservation of this species will depend on a more detailed understanding of how flowering drives population dynamics.