摘要：Since the first breeding in the Helsinki area (60°N, 20°E) in 1989, barnacle geese (Branta leucopsis) have increased drastically. In 2010, the number of nesting geese was estimated at 1440 pairs while the post-breeding population was 8400 individuals. The Helsinki area was clearly an open niche for this arctic species. Geese nested in the relatively natural archipelago and broods used urban lawns for foraging. This behaviour may indicate that by nesting on small islands geese avoid predation by terrestrial mammalian predators and by moving to urban lawns broods decrease predation risk by avian predators. Furthermore, during the autumn, geese foraged on urban lawns and in cultivated fields and roosted in coastal waters. The use of post-breeding habitat is again likely linked with predator avoid- ance. We suggest that the successful establishment of the barnacle geese is due to a combi- nation of high brood production and low predation rate, and this is possible to achieve by using the landscape in a complementary manner.
