Antibacterial and anatomical defences in an oil contaminated, vulnerable seaduck

Oil-spills have killed thousands of birds during the last 100 years, but non-lethal effects of oil-spills on birds remain poorly studied. We measured phenotype characters in 279 eiders Somateria mollissima of which 13.6% were oiled. We tested the hypotheses that (1) the morphology of eiders does not change due to oil contamination; (2) the anatomy of organs reflects the physiological reaction to contamination e.g. increase in metabolic demand, increase in food intake and counteracting toxic effects of oil; (3) large locomotion apparatus that facilitates locomotion increase the risk of getting oiled; and (4) individual eiders with a higher production of secretions from the uropygial grand were more likely to have oil on their plumage. We tested whether 19 characters differed between oiled and non-oiled individuals, showing a consistent pattern. The final model retained seven predictor variables showing relationships between eiders contaminated with oil and food consumption, flight and di...