caa a22 4500 463176219 CHVBK 20180406164826.0 cr unu---uuuuu 170326e20070401xx s 000 0 eng 10.1007/s10336-007-0123-7 doi (NATIONALLICENCE)springer-10.1007/s10336-007-0123-7 Population trend over 100years and conservation needs of breeding sandwich terns ( Sterna sandvicensis ) on the German North Sea coast [Elektronische Daten] [Stefan Garthe, Bernd-Olaf Flore] The breeding population of the sandwich tern (Sterna sandvicensis) on the German North Sea coast has undergone substantial fluctuations throughout the last 100years. Numbers of breeding birds were fluctuating quite strongly in the first 30years of the twentieth century. From 1930 to the mid-1950s, a relatively steady decrease occurred. A minimum was reached in 1965 with 2,243 pairs. Around 1970, numbers increased quite markedly up to the mid-1990s and reached a centurial maximum with 10,138 pairs in 1996. Most recently, the numbers have dropped to only 5,681 pairs in 2005, the lowest number over the last 30years. Some colonies have existed over long periods, others only for short periods, with often substantial and sudden changes. The distribution at sea was studied by transect counts from ships. During the reproductive period, high totals were found between the mainland coast and the islands, up to 30km from the outer coast/island line. The seaward extent of the sandwich tern distribution coincided quite well with the 20-m depth line. Maximum foraging ranges for single colonies were estimated to be ca. 45km for Trischen, ca. 35km for Norderoog and ca. 30km for both Scharhörn/Nigehörn and Juist. Overall flight ranges for all colonies were estimated at 33.8km for 95% of the birds. Germany has a high international responsibility for the protection of this species. Only a few colonies exist every year, making this species very vulnerable to anthropogenic disturbance, pollution events and fishing activities. Dt. Ornithologen-Gesellschaft e.V., 2007 Conservation nationallicence Distribution nationallicence Foraging range nationallicence Population trend nationallicence Sterna sandvicensis nationallicence Garthe Stefan Research and Technology Centre (FTZ), FTZ Westküste, University of Kiel, Hafentörn 1, 25761, Büsum, Germany aut Flore Bernd-Olaf Gartlager Weg 54, 49086, Osnabrück, Germany aut Journal of Ornithology Springer-Verlag 148/2(2007-04-01), 215-227 0021-8375 148:2<215 2007 148 10336 https://doi.org/10.1007/s10336-007-0123-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10336-007-0123-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Garthe Stefan Research and Technology Centre (FTZ), FTZ Westküste, University of Kiel, Hafentörn 1, 25761, Büsum, Germany aut NATIONALLICENCE 700 1- Flore Bernd-Olaf Gartlager Weg 54, 49086, Osnabrück, Germany aut NATIONALLICENCE 773 0- Journal of Ornithology Springer-Verlag 148/2(2007-04-01), 215-227 0021-8375 148:2<215 2007 148 10336 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer