Song Structure and Singing Strategies in the Genus Luscinia in Different Habitats and Geographical Areas

The structure of song and song propagation of studied populations of the Finnish thrush nightingale, the Mediterranean nightingale and the bluethroat (L. svecica) are in accordance with the prediction that birds living in less open habitat and usually singing inside the forest canopy, use more whistles and modulated elements and less trilled syllables (especially fast trills) in their songs than the species in more open habitats. However, the effects of the geographical location and other species in song communities are greater than that of habitat. The birds also seem to be able to improve their long distance communication easier by change in singing behaviour than by change in song-structure. The thrush nightingale males in the northern population improved detectability of their song by singing at midnight when most other species in the bird community are silent. At the same time the males increased song length and decreased intersong pauses, which increased their total vocalizing time and improved the receivers' possibility to detect their acoustic information. This strategy presumably improves rapid pair formation, which is important for long distance migrants in the northern latitudes with short favorable season for breeding and subsequent moulting.