Males of the common Australian libellulid O. caledonicum defended small territories at a pond in areas where there was open water at the shoreline. The density of males at the pond edge and the proportion of time spent in flight was greatest at midday. Females visited open shoreline to oviposit in shallow water for a period of about one minute. Males captured incoming females and copulated for periods ranging from 6 s to about 20 min. Unlike some other spp. of Orthetrum, prolonged copulation was apparently not practised exclusively by subordinate males unable to secure a territory. Alternative hypotheses on the variation in copulation duration are presented.