Dynamics of breeding site choice of Red-throated Loon Gavia stellata—abandonments, new establishments and reoccupations

Abstract

Red-throated Loons Gavia stellata have disappeared from breeding sites regularly used in the mid-1990s, but it is not clear if this reflects a population decline or movements to other sites. Therefore, we searched for potential breeding sites, including sites with old records, in three regions in southern Sweden, where it was possible to repeat surveys conducted in the past. A pattern of abandonment and return to breeding sites was verified; around 30% of the sites were abandoned over a 10-year period, but the loss was largely compensated by establishment at new sites or return to sites used in the past. But almost one quarter of the sites were used in about 75% of the breeding seasons across a period of more than 30 years. Annual breeding success at these sites did not differ from that at the other, less frequently used sites. However, the most continuously used sites produce a larger total of young than other sites and are therefore important for long-term recruitment. They should be identified and prioritised for protection and management.