Singing behind the stage: thrush nightingales produce more variable songs on their wintering grounds

Abel Souriau, Nicole Geberzahn, Vladimir V Ivanitskii, Irina M Marova, Jana Vokurková, Radka Reifová, Jiři Reif & Tereza Petrusková
The songs of migratory passerine birds have a key role in mate attraction and territory defence during the breeding season. Many species also sing on their wintering grounds, but the function of this behaviour remains unclear. One possible explanation, proposed by the song improvement hypothesis, is that the birds take advantage of this period to develop their singing skills for the next breeding season. If so, non-breeding songs should reflect features of an early phase...
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