Home ranges and movements of resident graylag geese (Anser anser) in breeding and winter habitats in Bavaria, South Germany.

In several countries in northwestern Europe, the number of resident greylag geese (Anser anser) has increased by up to 20% a year over the last few decades. The increasing numbers of geese are causing problems in tourism and agriculture. The number of resident greylag geese visiting the Altmuehlsee lake, a recreational area in the south of Germany, has also increased, especially in June and July. However, the geese leave the lake again at the beginning of August. 30 adult greylag geese were banded with telemetry transmitters during molting at the Altmuehlsee lake to determine when the geese leave the lake in August and what structures they need in their winter habitat. The distances the greylag geese flew from their resting sites to foraging sites were calculated, as well as the size of their home ranges and the proportions of each habitat type in the home range. It was found that the greylag geese used small home ranges while rearing their young, and fed close to the water. After molting, the size of their home ranges increased. They fed on fields and meadows around the lake. In the winter habitat, the geese also had a small home range, and they preferred eating grain and corn and the availability of an open body of water. In addition, one group of geese remained in the city of Munich during the winter, benefiting from supplementary food from people. This information helps us to understand the different requirements of resident greylag geese. It can be used to inform management decisions aimed at preventing agricultural damage. Special goose areas can for example be designated for the different periods in a goose's life cycle.