Livslång häckningsframgång för grågäss Anser anser häckande i södra Sverige

Abstract

During 1984–2009, 664 adults and 1,944 goslings of Greylag Geese Anser anser were neck-banded in south-west Scania, Sweden. After hatching the area was carefully searched for marked geese, giving more than 100,000 re-sightings. Of those marked as goslings 71% survived the first year, 52% the second year, and the oldest bird recorded was 25 years. About 50% of the survivors were recruited into the breeding population when two to three years old. Of 1,187 geese that survived for at least two years, 25% produced at least one brood of small young, and 18% at least one fledged young. The maximum life-time number of broods with fledged young was nine, but 50% of the geese known to have bred successfully produced only one brood of fledged young. Ten percent of the geese seen with small goslings produced 47% of all fledged young. The maximum number of fledged young for a goose of known age was 32 (age 15 years), but two geese marked as adults and followed for 16 and 17 years produced 40 fledglings each.