Male nightingales spend the winter practising

DESPITE THE ideas of Julia Monk and her colleagues on the frequency and normality of same-sex mating behaviour among animals (see article), some species do work hard to attract the opposite sex. That is why birdsong fills the air during the spring and summer breeding season. What has proved vexing to ornithologists is understanding why birds that migrate to warmer climes in winter often carry on singing even though there is no breeding to be done and no need to defend a territory. But a study just published in Behavioral Ecology and Sociobiology by Abel Souriau of Charles University in Prague and Nicole Geberzahn of the University of Paris, Nanterre, casts light on the matter. Mr Souriau and Dr Geberzahn suggest that winter is a period of practice for the summer performance to come.

Thrush nightingales are close kin to the common nightingale familiar in western Europe, but have a more easterly summer range. Males are innovative songsters, frequently plagiarising phrases from rivals and integrating them into their own tunes. They are also among the birds that carry on singing after they have migrated to Africa for the winter. So Mr Souriau and Dr Geberzahn decided to study the nature of their African songs.