Breeding success of Canada and Greylag Geese, Branta canadensis and Anser anser on gravel pits.

Abstract

Since the introduction of Greylag and immigration of Canada Geese to the study site in 1972, the number of nests of both species has increased, though a little erratically in the case of Greylags. Each year Canadas nested earlier than Greylags. About 90% of nests of both species were on islands. Island nests had significantly lower rates of predation (by Foxes and Crows) than mainland nests but when an island became accessible to Foxes most nests were destroyed. Overall nesting success was high for both species but gosling mortality was higher in Canada Geese than in Greylags. The earlier nesting of Canadas may account for the higher gosling mortality.