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Making yourself heard - a study of masking effects on blue tit Parus caeruleus singing interactions [abstract]

Angelika Poesel, Torben Dabelsteen and Simon Boel Pedersen (2002). Making yourself heard - a study of masking effects on blue tit Parus caeruleus singing interactions [abstract]. Bioacoustics, Volume 13 (2): 178

 

Abstract: 

Male territorial songbirds interact with each other via full song over long distances. The relative timing of strophes in these singing interactions conveys information about male dominance with overlapping as a dominant signal indicating willingness to escalate. Other birds may eavesdrop on such interactions to assess future opponents. This requires that individuals at a distance perceive the intended time pattern of the interaction despite attenuation and masking effects. Particularly during the dawn chorus, song of individual males is masked by vocalisations of other birds of the same and other species. We here report on a dual-speaker playback experiment in which we simulate alternating, overlapping and random patterns of singing interactions between male blue tits in a natural habitat. We record these 'interactions' and the vocalisations masking them with an array of four microphones (Acoustic Location System, ALS) representing eavesdroppers. The ALS allows the location of the masking birds. Masking in time and frequency range as well as signal-to-noise ratio between 'interactants' and masking birds are taken into consideration in the analysis. We expect the 'eavesdroppers' to perceive the temporal pattern of the interaction differently, depending on their location relative to the 'interactants' and the masking they experience. This study gives insight into how masking may constrain the perception of time patterns in singing interactions that vary considerably and therefore cannot be reconstructed from any internal representation.