Diversity and abundance of water birds in a subarctic lake during three decades

[摘要] The numbers of divers, ducks, gulls, terns and waders in the 15 km 2oligotrophic lake Takvatn, North Norway were estimated six times during 1983-2012. Systematic mapping surveys were done by boat within the first week after ice-break in June. Twenty-one species were observed over the years and 12 were regarded as breeding on the lake. Red-breasted merganserMergus serratorwas the dominant diving bird, with estimated minimum number of pairs varying from 15 to 39 among years. Black-throated diverGavia arctica(1-3 pairs), tufted duckAythya fuligula(2-15 pairs) and common scoterMelanitta nigra(1-5 pairs) bred regularly, while velvet scoterMelanitta fusca(1-2) and goldeneyeBucephala clangula(2-4) were found in some years and mallardAnas platyrhynchos(1 pair) and wigeonAnas penelope(1 pair) in one year. Common gullLarus canus(6-30 pairs) and arctic ternSterna paradisaea(2-35 pairs) bred in all years. Common sandpiperTringa hypoleucos(3-9 pairs) and redshankTringa totanus(1-4 pairs) were regular waders. Density variations of mergansers, gulls and terns are possibly related to density variations of three-spined sticklebacksGasterosteus aculeatus , their dominant fish prey. The water birds are important links in the food web of the lake.

[学科分类] 动物科学

[关键词] water birds;abundance;subarctic lake;food web