Drought-induced population decline in an exudivorous mammal and its relevance to forest management

Abstract

Droughts are predicted to increase in frequency and severity with climate change, so understanding their influence on species is fundamental to future conservation actions. Knowledge of whether species are at risk of decline due to drought may change the direction of how species and forests are managed. Exudate feeding non-flying mammals may be particularly sensitive to drought conditions, due to negative effects on exudates, but few studies of adequate length have been conducted. We investigated whether occupancy and abundance of a threatened exudivorous mammal, the yellow-bellied glider (Petaurus australis), were influenced by an extreme drought in eastern Australia. We conducted repeat surveys over eight years, which coincided with a drought that peaked in year 6, and was followed by two years of above average rainfall. Modelling suggested a slight decline in occupancy over the eight years (0.96–0.89). A marked decline in the probability of detection from pre-drought (0.72; 95 %CI: 0.65–0.79) to post-drought (0.30; 0.19–0.40), suggested a decline in abundance had occurred. Data on the maximum number of individuals detected per occupied site per year confirmed a decline in abundance. Counts of ≥ 3 individuals were recorded at 42% of occupied sites before the drought but at only 6% of occupied sites after the drought, equating to a 48% decline in abundance. These findings suggest that occupancy may be an unreliable measure of drought response in this species. Other exudivorous mammals may be sensitive to drought and require detailed study. Identifying drought refuges for these species should be added to existing forest management actions.