Factors affecting the breeding performance of a marked Greylag Goose Anser anser population in south Sweden

Abstract

The variation in breeding performance of Greylag Geese marked with individual neck-collars in an increasing population at four lakes in southwest Scania was studied during 1985-1992. During this period, the population increased from 93 to about 425 pairs. By neck-banding, the migration routes, staging areas and wintering areas can be established for a high proportion of the breeding birds. Overall, 65% of experienced breeders produced a brood of young. The mean clutch size was 5.36 eggs, the mean brood size of small young 4.60, and at fledging 3.72. Early arriving pairs were more successful than late pairs. Dutch wintering birds were more successful than Spanish wintering ones. Significant differences in brood size were found between lakes, and these differences were not related to arrival pattern or wintering area. Eighty-nine per cent of the broods produced at least one fledged young. Survival to fledging was significantly lower at lakes with poor feeding areas. Geese marked as young were recruited to the breeding population at ages from two to six years, pairs including inexperienced birds having a poor result.