Aggressive responses of male sedge warblers ( Acrocephalus schoenobaenus) to playback of species song and sympatric species song, before and after pairing

Abstract

Playback experiments with species song elicited strong levels of aggression from unpaired sedge warbler males in territory. After pairing, although a significant decrease in aggression was detected it was sufficient to maintain territory throughout the breeding season. As males ceased to sing upon pairing, it seems unlikely that habituation to song was responsible for the decrease in aggression. Experiments with sympatric reed warbler song confirmed the existence of interspecific aggression. In unpaired males the lower level of interspecific aggression was similar to that in paired males in response to species song. Interspecific aggression did not show a significant decrease after pairing, responses were much more variable and possibly related to the individual's particular territorial situations both past and present.