title: Isotopic analysis of island House MartinsDelichon urbicaindicates marine provenance of nutrients.
abstract: The presence of one of the largest colonies of House Martins in Europe on the small island of Stora Karlsö, Sweden, led us to investigate the source of their food by analysis of stable isotopes of carbon and nitrogen. Carbon isotopic values of House Martin nestlings were the same as those of Common GuillemotUria aalgenestlings fed on marine fish, but differed from local Collared FlycatcherFicedula albicollisnestlings fed on woodland insects. We infer that these House Martins fed their chicks almost exclusively on insects that had used nutrients derived from seabirds, indicating a dependence on the presence of a large seabird colony. We suggest by extension that some populations of island passerines of high conservation importance may also be dependent on nutrient subsidies from seabird colonies.
authors: College of Medical, Veterinary and Life Sciences, University of Glasgow Glasgow, UK.
authors: Adam D P
authors: AD
authors: Cross
authors: Stockholm Resilience Centre, Stockholm University Stockholm, Sweden.
authors: Jonas
authors: J
authors: Hentati-Sundberg
authors: Stockholm Resilience Centre, Stockholm University Stockholm, Sweden.
authors: Henrik
authors: H
authors: Österblom
authors: Scottish Universities Environmental Research Centre East Kilbride, UK.
authors: Rona A R
authors: RA
authors: McGill
authors: College of Medical, Veterinary and Life Sciences, University of Glasgow Glasgow, UK.
authors: Robert W
authors: RW
authors: Furness
keywords: Common Guillemot; food webs; passerines; stable isotope analysis