Sympatric Atlantic puffins and razorbills show contrasting responses to adverse marine conditions during winter foraging within the North Sea

• Published in: Movement Ecology
• Main Authors: St. John Glew, Katie, Wanless, Sarah, Harris, Michael P., Daunt, Francis, Erikstad, Kjell Einar, Strøm, Hallvard, Speakman, John R., Kürten, Benjamin, Trueman, Clive N.
• Other Authors: Red Sea Research Center (RSRC), Department of Ocean and Earth Science, University of Southampton Waterfront Campus Southampton SO143ZH UK, Centre for Ecology & Hydrology Bush Estate Penicuik EH26 0QB UK, Norwegian Institute for Nature Research, Fram Centre N-9296 Tromsø Norway, Norwegian University of Science &Technology (NTNU), Centre for Biodiversity Dynamics, Department of Biology N-7491 Trondheim Norway, Norwegian Polar Institute, Fram Centre Postbox 6606 Langnes NO-9296 Tromsø Norway, Institute of Genetics and developmental Biology, Chinese Academy of Sciences Beijing China, Institute of Biological and Environmental Sciences, University of Aberdeen Aberdeen Scotland, UK, School of Natural and Environmental Sciences, University of Newcastle Newcastle-upon-Tyne NE1 7RU UK
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer Nature 2019
• Subjects: Alca torda; fratercula; Fratercula arctica
• Online Access: http://hdl.handle.net/10754/660352; https://doi.org/10.1186/s40462-019-0174-4

Background: Natural environments are dynamic systems with conditions varying across years. Higher trophic level consumers may respond to changes in the distribution and quality of available prey by moving to locate new resources or by switching diets. In order to persist, sympatric species with similar ecological niches may show contrasting foraging responses to changes in environmental conditions. However, in marine environments this assertion remains largely untested for highly mobile predators outside the breeding season because of the challenges of quantifying foraging location and trophic position under contrasting conditions. Method: Differences in overwinter survival rates of two populations of North Sea seabirds (Atlantic puffins (Fratercula arctica) and razorbills (Alca torda)) indicated that environmental conditions differed between 2007/08 (low survival and thus poor conditions) and 2014/15 (higher survival, favourable conditions). We used a combination of bird-borne data loggers and stable isotope analyses to test 1) whether these sympatric species showed consistent responses with respect to foraging location and trophic position to these contrasting winter conditions during periods when body and cheek feathers were being grown (moult) and 2) whether any observed changes in moult locations and diet could be related to the abundance and distribution of potential prey species of differing energetic quality. Results: Puffins and razorbills showed divergent foraging responses to contrasting winter conditions. Puffins foraging in the North Sea used broadly similar foraging locations during moult in both winters. However, puffin diet significantly differed, with a lower average trophic position in the winter characterised by lower survival rates. By contrast, razorbills' trophic position increased in the poor survival winter and the population foraged in more distant southerly waters of the North Sea. Conclusions: Populations of North Sea puffins and razorbills showed contrasting foraging responses when ...