Investigations of the perching site selection by adult dragonflies were carried out at the “Tritonwasser”, on the “Donauinsel”. Special attention is drawn to the perching behaviour of Orthetrum cancellatum and Crocothemis erythraea. Both spp. select a great variety of structures and preferably perch in heights between ground level and 70 cm. Crocothemis showed a stronger preference for perching sites over the water surface. Other spp. observed were Coenagrion puella, Erythromma viridulum and Ischnura elegans.