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 ~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.