Swedish Bird Survey: Swedish coastal bird monitoring programme (Nationella kustfågelövervakningen)

Study Extent

Geography: There are 200 archipelago squares (2 x 2 km) distributed along the Swedish coastline. The squares are distributed to the 14 coastal counties in proportion to how many islands there are in each county. A county that contains many islands has been allocated more squares than a county with fewer islands. Each square contains at least one island, and the locations of the squares are fixed. Timing and frequency: The aim is for all squares to be surveyed once every year during the main breeding season for the majority of species. Since Sweden is a long country the survey is carried out during different time intervals in different parts of the country: All counties south of Gävleborg county: 20 May – 5 June Gävleborg county: 25 May – 10 June Västernorrland county: 1 – 15 June Västerbotten county: 5 – 20 June Norrbotten county: 10 – 25 June

Sampling

The archipelago squares are surveyed mainly by boat. All islands located within a square are scanned from a distance of maximum 50 metres as the boat is driven around them. Some predetermined islands are surveyed by going ashore, and this is repeated every year. All birds within a square should be counted regardless of whether they are on/near the islands or out on open water. In the counties of Norrbotten, Västerbotten, Västernorrland and Gävleborg it is mandatory to register the numbers of birds on open water vs on islands including the surrounding 100m buffer of water. For all other counties this is optional. The boat is driven in such a way as to minimize the distance travelled. Hence, open water is only scanned on the route to/from/around islands. The surveyors do their best to determine whether birds close to the square border are within it or outside. The two squares I0002 and I0003 (containing the very bird rich islands Stora Karlsö and Lilla Karlsö) are not surveyed in the same way as other squares. Here the survey is instead carried out in a number of subsquares on the islands. In addition, data for razorbills on Stora Karlsö (I0002) are not included here at present. All individuals except for pulli and juveniles are counted. However, in 2017 counting common eider pulli was introduced. Counting eider pulli was mandatory in eight of the 14 counties from the start, but optional in the others. It became mandatory in 2018 in Halland and Uppsala and in 2020 in Gävleborg, Norrbotten and Västerbotten, but it is still optional in Gotland. Where eider pulli are counted, the dominating size class of the total number of pulli within a square is also reported according to this scale: Size class 1 includes pulli that are < 25 % of the adult size. Size class 2 includes pulli that are 25-50 % of the adult size. Size class 3 includes pulli that are 50-75 % of the adult size. Size class 4 includes pulli that are > 75% of the adult size.

Quality Control

Data is checked and validated by the project leaders, specifically species identity, numbers and geographical location. Confidence in the data is good.

Method steps

1. See sampling description.

All species within the following groups are surveyed: Ducks, geese and swans (Anatidae) Grebes (Podicipedidae) Divers (Gaviidae) Waders, gulls and auks (Charadriiformes) Cormorants (Phalacrocoracidae) Herons (Ardeidae) The following species are also included in the survey: Rock pipit (Anthus petrosus) Eurasian coot (Fulica atra) (from 2016) Common crane (Grus grus) (from 2016) Osprey (Pandion haliaetus) White-tailed eagle (Haliaeetus albicilla) Crow (Corvus corone) Raven (Corvus corax) American mink (Neovison vison) Red fox (Vulpes vulpes) (from 2021) Badger (Meles meles) (from 2021) Species with a security class 4 or higher (according to the Swedish species information centre (Artdatabanken)) are not shown in this dataset. Currently this concerns one species only: White-tailed eagle (havsörn; Haliaeetus albicilla). In addition, razorbills on Stora Karlsö (square I0002) are at present not included here. All observed individuals (except pulli and juveniles) of the above mentioned bird species are counted. Special case: In some counties counting Common eider pulli is or has been optional while in other counties it is mandatory. Information about whether common eider pulli have been counted or not can be found in the "extended measurement or fact table". Mammalian predators are recorded with presence/absence only.

1. Animalia
   common name: Animals rank: kingdom
2. Chordata
   common name: Chordates rank: phylum
3. Aves
   common name: Birds rank: class
4. Mammalia
   common name: Mammals rank: class

All data is collected within Sweden.