Can Artificial Tree Cavities Provide Population Support to Cavity-Dependent Non-Flying Mammals?

Anthropogenic disturbances to forests have reduced densities of tree cavities and potentially led to declines in the abundance of cavity-dependent mammals. Artificial cavities (nest boxes, carved and drilled cavities) may be used to restore habitat quality that may otherwise take many decades to recover naturally. We investigated whether artificial cavities could support populations of two species of Australian cavity-dependent mammals, the brush-tailed phascogale (Phascogale tapoatafa, 200 g) and the inland sugar glider (Petaurus notatus, 110 g). This is the first detailed study of non-flying mammals that has attempted to do this. We censused animals twice per year over 6 years in 164 nest boxes arranged in 74 clusters through a 600-ha forest block deficient in tree cavities. We addressed four key questions: (1) were nest boxes used by a large number of individuals of the target species, (2) was use sustained over multiple years, (3) were nest boxes used for breeding and (4) what proportion of the local population might be supported by the nest boxes? We detected up to 58 adult phascogales and 232 adult sugar gliders in our boxes. Use was sustained over time with a mean probability of occupancy per cluster per year of 0.66 in the phascogale and 0.89 in the sugar glider. Differences in life history influenced how breeding was assessed. We detected breeding in 98% of female phascogales and at 68% of sites with sugar gliders. We estimated the total number of adults of each species that might occupy our study area based on their known spatial requirements. Our nest boxes potentially supported up to 61% of the adult female phascogales and 72% of the adult sugar gliders in the study area. Provision of shelter and breeding sites for such large segments of populations could be highly beneficial to manage populations of cavity-dependent mammals.