Résumé
The aim of this study is to describe and investigate geographic variation of Blue Tit Parus caeruleus song. We recorded songs at seven sites situated in the French Mediterranean region, five on Corsica and two on the mainland of southern France. Blue tits from these two regions belong to two subspecies differing significantly in body size. Both subspecies inhabit two distinct vegetation types, broad-leaved deciduous versus evergreen woodland. We analysed 570 songs recorded. On the mainland Blue Tit song was characterised by the presence of a rapid trill. This was not the case on Corsica, where the variation in song was also much more pronounced than on the mainland. The smaller subspecies of Corsica produced higher song frequencies and shorter songs. The frequency and the duration of intervals between notes differed between the songs of the two vegetation types on Corsica. On the mainland no such difference occurred. These results suggest that both body size and vegetation structure account for some of the geographic variation observed in Blue Tit song.