Schwemmer, PhilippCorman, Anna-MarieKoch, DanielaKoschorreck, Jan2024-06-162024-06-162019https://doi.org/10.60810/openumwelt-484https://openumwelt.de/handle/123456789/4772The German Federal Environmental Agency (UBA) with the Environmental Specimen Bank monitors the development of contaminants in humans and the environment since the 1980s. Eggs of the Herring Gull Larus argentatus are used as an important indicator reflecting the pollution of the Wadden Sea of the German North Sea coast. Strong inter-annual variability in contaminant load was found in the samples during the last years. For a proper interpretation of the trends, it is of great importance to know the possible origins of contaminants. Therefore, the goal of this study was to describe the individual habitat use of adult Herring Gulls from the island of Trischen during the course of the year using GPS telemetry. A major focus was set on the space use of females during pre-breeding, as this is the expected time during which contaminants taken up by the female are deposited in the eggs. Herring Gulls of both sexes (n = 9 males; n = 8 females) used predominantly intertidal flats south of Trischen during breeding 2016. Terrestrial habitats at a maximum distance of 20 to 30 km were visited by only a few individuals. Pellet analyses confirmed these patterns through high proportions of Shore Crabs Carcinus maenas and bivalves in the diet. Also, stable isotopes analyses showed a high degree of marine foraging and suggested bivalves as the main prey source. Most females migrated to the mainland of Lower Saxony during winter and used mainly industrial areas and business parks, whereas most of the males stayed in intertidal flats close to the colony. Females still used terrestrial habitats with a proportion of 70% of their total time during pre-breeding 2017. Hot spots were located in the vicinity of waste incineration and processing plants, waste management companies for food remains, industrial estates and harbours as well as (to a lower extent) on farmland and pastures. Herring Gulls spent higher proportions in terrestrial areas during breeding 2017 as compared to the year before. Hot spots that had been used already during pre-breeding were still frequently visited during the breeding period. Overall, the space utilisation varied highly between different individuals and consecutive breeding times. The results of this study indicate that a high proportion of contaminants in Herring Gull eggs from Trischen is likely to originate from terrestrial habitats. These patterns match well the long-term data set of the UBA that proves contaminants from industrial sources and from agriculture for recent years. Strong inter-annual variations are very likely to be explained by varying use of marine and terrestrial prey resources. Currently, contaminants are not analysed in individual eggs but in a single pooled sample. It is suggested to change this method and analyse contaminant levels in individual eggs as the current study clearly showed that the habitat use can differ considerably between individual herring gulls. Quelle: https://www.researchgate.net1 Onlineressource (Seiten 13-30)online resourcegerhttp://rightsstatements.org/vocab/InC/1.0/Wissenschaftlicher Artikel