To Drain or Not to Drain? –Intermittent Swamp Drainage and Waterbird Breeding

Abstract

The breeding activity of waterbirds - ducks, cormorants, ibises, herons and grebes - are examined in relation to water level fluctuations at Booligal, N.S.W. In the swamp complex studied, most species bred best after a flood on a previously dried out basin. A rise in water level in an already wet basin had no effect. However, the specialist fishers - Darters, Little Black Cormorants and Intermediate Egrets - bred best when the swamps had been filled for some time and a climax of Ribbonweed and tish had developed. The importance of a previous drying phase to waterbird breeding rather than a flood is stressed and the usefulness of drying swamps intermittently in waterbird management considered.