An analysis of Mute Swan Cygnus olor breeding data

Abstract

Data for Mute Swans breeding in the Oxford Study area during 1977-81 were first analysed by Birkhead et al. (1983). With the advantage of extra data for 1983-88, their models are reviewed and new features incorporated in the current analysis. The date of lay of the first egg of a clutch is shown to be dependent on the mean winter temperature and the pen’s experience. The clutch size is shown to be dependent on the date of lay. The proportion of cygnets fledged from a clutch is shown to be dependent on the date of hatching and both on the pen and cob genotypes.