@article{Olsson_Hentati-Sundberg_2017, place={Lund, Sweden}, title={Population trends and status of four seabird species (Uria aalge, Alca torda, Larus fuscus, Larus argentatus) at Stora Karlsö in the Baltic Sea}, volume={27}, url={https://journals.lub.lu.se/os/article/view/19558}, DOI={10.34080/os.v27.19558}, abstractNote={<p>The island of Stora Karlsö hosts the largest colonies of fish-eating seabirds in the Baltic Sea. However, recent and reliable estimates of the number of breeding pairs of the main species have been missing. Based on a complete census in 2014, we estimated the number of Common Guillemots <em>Uria aalge</em> to 15,700 pairs, more than half (up to 70%) of the Baltic Sea population. The number has almost tripled since the early 1970s and the increase has been particularly strong the last 11 years, with an annual increase of 5.1%. We counted 24,600 individual adult Razorbills <em>Alca torda</em> and estimated it to correspond to a maximum of 12,300 pairs in 2015–2016 (census over two seasons). The colony has grown strongly; on average by 5.6% annually since the early 1970s, and Stora Karlsö now hosts up to 30% of the Baltic Sea population. Stora Karlsö also hosts colonies with about 300 pairs each of Lesser Black-backed Gull <em>Larus fuscus</em> and Herring Gull <em>Larus argentatus</em>. The gulls’ trends are negative, with an average annual decline the last 10-year period by 5.0% and 6.2%, respectively.</p>}, number={2–4}, journal={Ornis Svecica}, author={Olsson, Olof and Hentati-Sundberg, Jonas}, year={2017}, month={Oct.}, pages={64–93} }