The aim of this investigation was to determine to what extent song repertoires and singing behaviour of chaffinches (Fringilla coelebs) evolved as a means by which resident birds deceive intruders into overestimating the density of residents, making the area appear less suitable for settlement. (1) The chaffinches studied did not show a significant tendency to change song posts synchronously any more than would be expected by chance. (2) Approximately 90% of song type/song post changes were asynchronous. (3) Half of the birds did not repeat their song types with equal frequency, nor did they distribute their singing effort evenly over all the song posts. (4) The degree of similarity between song types in the same repertoire and the degree of similarity between song types from different individuals were not found to be significantly different. (5) No correlation between song rate and repertoire size was found, but it was concluded that seasonal biases strongly restricted this facet of the investigation. On the basis of these findings it is concluded that the evolution of repertoires and singing behaviour in chaffinches seems unlikely to have occurred in conformity with the Beau Geste hypothesis.