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Site description (2000 baseline):
Site location and context
The site is a large, nutrient-rich freshwater lake, situated near the city of Moss. The lake is connected with the Oslofjord by the Mosse-elva river. Forestry is widespread; military activity mainly comprises low-flying planes from a nearby air base.
This is an important breeding site for
Pandion haliaetus, with the highest known density of natural nests in Norway.
Pressure/threats to key biodiversity
Nutrient pollution by agricultural activities is a problem. Forestry may be a problem for
Pandion haliaetus, since trees are cut close to the nests; such activity should be planned, to avoid nest-sites and to reduce disturbance to nesting birds. Vannsjo supplies drinking water to Moss, and the local authorities take action to reduce pollution at the lake. Low-flying planes do not seem to affect
Pandion haliaetus in any way. There is limited tourism in the area, and there are restrictions on motor-boats (maximum 5 knots within 100 m of land). Access to the Nature Reserve is restricted during the breeding season. Local ornithologists ring several bird species in the area, including
Pandion haliaetus.
National Low
International None330 ha of IBA covered by Nature Reserve (Vestre Vannsjø, 330 ha).
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Lake Vansjø (Norway). Downloaded from
https://datazone.birdlife.org/site/factsheet/lake-vansjø-iba-norway on 23/12/2024.
