Résumé
In this study there was no positive significant relationship between the quality of male great tits, as measured by average strophe length (a strophe is a short burst of song), and territory quality. (1) Males singing longer strophes did not defend territories in areas of higher recruitment, and (2) naturally settling males were better singers than replacement birds were. The second result was probably caused by a difference in age composition of the two groups, because naturally settling yearlings and replacement yearlings did not differ significantly in average strophe length. These observations on a non-migratory species are in contrast to those of several other studies on passerine birds, which were mostly concerned with migratory species. The relationship between male quality and territory quality is predicted to be closer in species that migrate than in non-migratory species.