Entwicklungen in der ornithologischen Kommunikationsforschung

Functional communication research explores the relations between bird song and mate choice or territory defence. This is usually done by examining the time of day or season when a bird sings, and how it uses particular songs or singing strategies, i.e. what role it takes in singing interactions with rivals. Male Nightingales Luscinia megarhynchos can be heard singing at night until the be- ginning of June. However, males singing that late in the season are usually un- paired, since males cease nocturnal singing after pair formation. Nocturnal song of males apparently serves to attract a mate, and mate-searching females indeed prospect the breeding area mostly at night. At dawn, however, both paired and unpaired males are singing, suggesting that dawn singing is important to an- nounce territory occupancy to prospecting males. As aggressive signals, male Nightingales often use trills with a wide frequency bandwidth and high element repetition rate, or overlap the songs of a rival in singing interactions. Currently, communication research is being broadened both at a temporal and a spatial scale: microphone arrays are being used to record several males in a neighbour- hood to study communication networks; further, spatial movements of singing rivals and long-term influences of singing interactions on territorial behaviour are increasingly being taken into account. At present, almost no information is available on the song of long-distance migrants at their African wintering sites. In Ghana, in the beginning of February, we found a high density of Nightingale territories in the derived savanna, and Nightingales were singing at dawn and throughout the day, but not at night. A current field of research is the singing behaviour at urban study sites. However, it is almost completely unknown how wild bird feeding affects song and ecology of birds within our towns and cities, offering the opportunity to break new scientific ground in one's own garden.