Korte mededelingen

In a breeding population of Black Swans Cygnus atratus near Bergen op Zoom in the South-West Netherlands eight breeding cases were recorded, of which seven were successful!, giving a nesting success of 88%. Average brood size was 3.2. Breeding was reported in may (1), june (1), august (1), September (3), October (1) and november (1), giving the impression of a late breeding season. This contradicts the study of Lensink (1996a), who found a season normal for the Northern hemisphere. Probably his data were biased by not finding late breeders because of the absence of breeding bird surveys in that time of the year. More detailed study is needed to find out what factors determine the onset of the breeding circle of this southern species, living in the Northern hemisphere.