The Influence of Fire and Foliar Chemical Composition on the Diet of Southern Greater Gliders ( <i>Petauroides volans</i> )

ABSTRACT Understanding diet selection in threatened species is crucial for effective conservation planning, particularly where bushfires alter food availability and quality. In Australian eucalypt forests, Eucalyptus leaves are the primary food for several arboreal marsupials, such as the southern greater glider ( Petauroides volans ). Some eucalypt species regrow leaves epicormically after fire, and these leaves can differ in concentrations of deterrent compounds like unsubstituted B‐ring flavanones (UBFs) compared to adult foliage. Little is known about how greater gliders respond to variation in UBF concentrations or their use of post‐fire regrowth. We investigated whether UBF and available nitrogen concentrations in epicormic regrowth and adult leaves of Eucalyptus fastigata and E. sieberi influenced feeding by greater gliders. Epicormic leaves had lower UBF concentrations than adult leaves in both eucalypt species, whereas available nitrogen concentrations were higher in epicormic leaves of E. fastigata but lower in E. sieberi . Greater gliders consumed both leaf phases in similar amounts. There was a negative relationship between UBFs and food intake in E. fastigata , but UBF concentrations were very low in this species so other constituents may have been driving the response. Intake of E. sieberi , which had substantially higher UBF concentrations, was best explained by an interaction between UBFs and available nitrogen, but the role of UBFs remained unclear. Leaf intake correlated well with near‐infrared spectral properties, further demonstrating that foliar chemical composition affects feeding but also suggesting that unmeasured foliar chemicals are influential. Overall, the findings show that greater gliders are relatively tolerant of UBFs, consistent with observations that they eat many monocalypt species in the wild. Importantly, the results give confidence that greater gliders can consume epicormic regrowth following fire in some forest types, despite post‐fire changes in leaf quality.