Greater glider (Petauroides volans) den tree and hollow characteristics

Hollow-bearing trees provide essential habitat for a range of threatened Australian wildlife species. Limited data exist for the hollow choice of greater gliders (Petauroides volans). This study aimed to provide the first comprehensive overview of the dimensions and characteristics of the den trees and hollows used by greater gliders, in the context of an endangered population. Through spotlighting and stag-watching, we identified 68 greater glider hollows in 54 den trees. When compared to reference hollows, greater gliders appeared to be preferentially choosing dens based on tree species, tree diameter at breast height (DBH), hollow type, hollow height and hollow depth. The aspect, entrance diameter, and cavity wall thickness of hollows did not appear to be influencing den choice, when compared to reference hollows. Greater gliders preferred to den in blackbutt (Eucalyptus pilularis) trees with a mean DBH of 114.1 cm (±4.3 cm). Hollows were most commonly a ‘branch end’ type of hollow. Mean depth of hollows was 252 cm (±12 cm). Mean hollow height was 15.4 m (±0.4 m). While not significant, hollows had a mean minimum hollow entrance of 18.1 cm (±0.6 cm) and a mean maximum cavity wall thickness of 8.0 cm (±0.7 cm). It is likely that hollow depth contributes to temperature buffering within dens, which is important for den choice as greater gliders are highly sensitive to hot temperatures. Our findings have important conservation implications for assessing den trees, and for improving designs of nest boxes and artificial cavities.