Udvikling i ynglebestanden af Fjordterner i Danmark 1970-2012

摘要

The Common Tern is an Annex I species on the EU Birds Directive. It is designated as a breeding species for 30 of the Danish SPAs. Knowledge about breeding occurrence of terns has been collected mainly in projects and surveys initiated and carried out by volunteers, in some cases in collaboration with the Danish Ornithological Society/ BirdLife Denmark. The most substantiel countrywide information about breeding occurrence of Common Terns has been provided by the Danish Tern Group, the Gull and Tern Group and the locality and atlas projects organized by the Danish Ornithological Society. Some localities have been followed on an almost annual basis by volunteers and/or by national or regional authorities. The Ministry of Environment initiated a national monitoring programme that ensured visits to a large number of potential breeding sites of Common Terns in 2006 and 2012. Furthermore, the Ministry hired Aarhus University to organize a national survey of breeding colonial coastal birds in 2010 and to build a database of existing data on breeding numbers of colonial coastal birds at all known breeding sites. To iden-tify the most reliable data for each breeding site, we went through all data collated for Common Terns and evaluated the quality of the count data.The development in breeding numbers is given in Appendix 1 for 15 of the most impor-tant breeding areas; the location of these areas is given in Fig. 1. For many years these areas housed 75-80% of the Danish breeding population.