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

• Published in: Fauna norvegica
• Main Authors: Klemetsen, Anders, Knudsen, Rune
• Other Authors: University of Tromsø, Norwegian Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Norwegian University of Science and Technology (NTNU), University Museum 2013
• Subjects: water birds; abundance; subarctic lake; food web; Arctic; Norway; Arctic tern; Common Sandpiper; Gavia arctica; Larus canus; Melanitta fusca; Melanitta nigra; North Norway; Sterna paradisaea; Subarctic; velvet scoter
• Online Access: http://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/1584; https://doi.org/10.5324/fn.v33i0.1584

The numbers of divers, ducks, gulls, terns and waders in the 15 km2 oligotrophic 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 merganser Mergus serrator was the dominant diving bird, with estimated minimum number of pairs varying from 15 to 39 among years. Black-throated diver Gavia arctica (1-3 pairs), tufted duck Aythya fuligula (2-15 pairs) and common scoter Melanitta nigra (1-5 pairs) bred regularly, while velvet scoter Melanitta fusca (1-2) and goldeneye Bucephala clangula (2-4) were found in some years and mallard Anas platyrhynchos (1 pair) and wigeon Anas penelope (1 pair) in one year. Common gull Larus canus (6-30 pairs) and arctic tern Sterna paradisaea (2-35 pairs) bred in all years. Common sandpiper Tringa hypoleucos (3-9 pairs) and redshank Tringa totanus (1-4 pairs) were regular waders. Density variations of mergansers, gulls and terns are possibly related to density variations of three-spined sticklebacks Gasterosteus aculeatus, their dominant fish prey. The water birds are important links in the food web of the lake.