The status and trends of seabirds breeding in Norway and Svalbard

Abstract

This report presents the updated sizes, trends and spatial distributions of the breeding populations of 17 seabird species breeding in Norway and Svalbard. The analyses are based on available census and monitoring data from SEAPOP; the Norwegian monitoring and mapping program for seabirds. In addition, the report presents results from a species-specific literature review of the most important prey items and drivers of population change. The report documents large-scale decadal changes in the seabird communities along the coast of Norway and Svalbard. A division of the populations into five geographical regions (North Sea & Skagerrak; Norwegian Sea; Barents Sea; Bjørnøya; and Spitsbergen) was used as a basis for the analyses of population dynamics from 1980 to present. 13 of the 35 regional seabird populations assessed have declined by more than 50% the last 25 years. 5 regional populations increased by more than 100% in the same period, while 8 populations showed large decadal fluctuations. Several populations were not assessed due to the lack of census and/or monitoring data. In order to improve the dataset, it is recommended that a census of breeding seabirds from Vesterålen to the Swedish border is completed. Declining populations were found in all regions and included all major ecological groups (i.e.; Pelagic surface-feeding (Ps), Pelagic diving (Pd), Coastal surface-feeding (Cs), Coastal benthic- feeding (Cb) and Coastal diving (Cd) seabirds). Populations with more than a 50% decline the last 25 years were: Common Gull (Cs), Lesser Black-backed Gull (Ps) and Atlantic Puffin (Pd) in the North Sea & Skagerrak; Great Cormorant (Cd), Common Eider (Cb), Black-legged Kittiwake (Ps) and Common Guillemot (Pd) in the Norwegian Sea; Herring Gull (Cs), Great Black-backed Gull (Cs), Black-legged Kittiwake (Ps) and Brünnich’s Guillemot (Pd) in the Barents Sea; Northern Fulmar (Ps) and Glaucous Gull (Ps) on Bjørnøya; and Brünnich’s Guillemot (Pd) on Spitsbergen. The populations of European Shag and Great Cormorant have shown large fluctuations with a notable increase in the population of Phalacrocorax carbo sinensis in North Sea & Skagerrak. Common guillemot has been increasing in the Barents Sea since the collapse in the population in the 1980s, however the population in the Norwegian Sea has been steadily declining since the early 1980s. Atlantic Puffin is declining in the North Sea and Norwegian Sea, but the population in the Barents Sea is stable or is increasing slightly. The datasets were too small to assess several of the large gull species in the Norwegian Sea. However, extensive monitoring in the North Sea & Skagerrak and recent censuses in the Barents Sea suggest declines by more than 50% in several of the gull populations in these areas. Black-legged Kittiwake has declined in all regions except for Bjørnøya. The large colonies of Brünnich’s Guillemot on Spitsbergen have declined from 1.15 million pairs in 1988 to 522 000 pairs in 2013. The colony on Bjørnøya (about 100 000 pairs) has in the same period been stable or declined slightly, while the small populations on the Norwegian mainland have almost disappeared. Northern Gannet has been increasing in Norway since the establishment of this species on Runde in the 1940s. The species has expanded northward and has recently established a small colony as far north as Bjørnøya. The review of diet studies highlighted the importance of the young age-classes of cod fish, the importance of pelagic forage fish species and in particular the importance of sandeel. Norway, Svalbard Seabirds, Population dynamics, Breeding population size Monitoring, cens Norge, Svalbard sjøfugl, populasjonsdynamikk, hekkebestander overvåking, kartlegging