Sound radiation patterns in Nightingale (Luscinia megarhynchos) songs

Songs of a Nightingale (Luscinia megarhynchos) were recorded in front of the bird (on-axis) and simultaneously at various off-axis angles. The pattern of sound radiation in the horizontal plane around the singing bird proved to be clearly directional with a median front-back difference (0degrees-180degrees) of 4.6 dB. This deviation from omnidirectionality seems to be an inevitable result of the bird's anatomy (i.e. sound shadow effects of the head and body) but some bird species may counteract the directionality of their songs by means of behaviour. Moreover, the directional song radiation pattern might be used to direct songs towards addressees of the signals.