Förändringar i flyttnings- och övervintringsvanor hos grågäss Anser anser från sydligaste Sverige under trettio år

Abstract

The recent increase of the Greylag Goose Anser anser population has caused complaints about crop damage. In response to this, the Nordic Collegium for Wildlife Research started a neck-banding program to elucidate the migration and movement patterns. During 1984–2009, 2,639 Greylag Geese were marked in a breeding area in SW Scania, southernmost Sweden. Up to and including 2012, 15,296 re-sightings were reported from outside the breeding area (in addition to more than 100 000 from the breeding area). In the early years of the study, the majority of the geese migrated to winter in southernmost Spain, staging in The Netherlands. In later years, hardly any individuals migrated to Spain, the majority staying in The Netherlands with an increasing proportion wintering in southern Sweden. From 1986 to 2017, the mean latitude for re-sightings changed ten degrees to the north. About 13% of the geese changed winter quarters between two consecutive winters. Moreover, the southward migration occurred much later in the autumn and the geese returned to the breeding areas about one month earlier in spring.