The breeding biology of mute swans Cygnus olor in southeast Cork, Ireland

The breeding success of mute swans in SE Cork from 1972-89 is analyzed. Data from 151 nests are presented. Eight percent of pairs that built nests failed to lay eggs. Mean final clutch size was 5.5 eggs. Some 71% of clutches hatched successfully. Mean brood size at fledging was 3.8 per clutch. No significant difference was found in mean number of cygnets produced per clutch across habitat types. -from Authors