The timing and duration of activity and foraging behaviour of mahogany gliders Petaurus gracilis was studied every 2 months over 2 years by direct observation. The amount of time spent active each night throughout the year ranged from 8 to 10.1 h (or 63–80% of the dark phase) and did not change significantly between the wet and dry seasons. Although gliders generally had one continuous period of activity, they were observed on eight occasions to return to their dens during the night for a mean of 85 min, with a mean entrance and exit being 22:59 and 00:25, respectively. The amount of time spent foraging (i.e. feeding and travelling) ranged from 40% of the time outside the den in January to 77% in September. The overall mean was 61.1%, with the remainder of the night spent either stationary (mean 24.3%), grooming (mean 11.8%), in the den and then re-emerging (mean 2.5%) or vocalizing (mean 0.3%). Activity comprised mostly the behaviours associated with foraging: feeding (44.9%), climbing (13.2%) and gliding (3.0%). The amount of time spent active and feeding was similar to that observed for other petaurid marsupials such as yellow-bellied glider P. australis, sugar glider P. breviceps and squirrel glider P. norfolcensis. There is a general relationship between diet, body size and amount of time spent feeding among the exudivorous gliders and folivorous possums, with feeding time increasing with increasing body mass in exudivorous possums and decreasing with increasing body mass in folivorous possums.