Composition of beached marine birds from an oiling event in southeastern Newfoundland and Labrador, Novermber 2004

Abstract

The waters off Newfoundland and Labrador, Canada, have one of the worst chronic oiling problems in the world. Although the species generally affected by chronic oiling is known, details on the sex, age and condition of birds killed are not well understood. In late November 2004, oiled seabirds began arriving on the beaches of eastern Placentia Bay. Over the next week, 409 oiled marine birds were collected, with Thick-billed Murres Uria lomvia (67%) and Dovekies Alle alle (23%) constituting the majority. Adult birds comprised 80% (n = 253) of Thick-billed Murres, 61% (n = 84) of Dovekies and only 38% (n = 16) of Common Murres Uria aalge. Sex ratios were close to unity (48.2% male, n = 189) for Thick-billed Murres, but male-biased for Dovekies (60.5%, n = 76) and Common Murres (85.7%, n = 14). Most Dovekies and Thick-billed Murres were found dead (83%), with the highest proportion found alive three and four days, respectively, after the first birds arrived. In spite of additional mass from the oil, body masses of Thick-billed Murres were low (mean: 742 g; range: 520-986 g; versus an expected 950 g for wintering birds). This study confirms previous assumptions that chronic oil pollution in Newfoundland affects all ages of Thick-billed Murres equally, because the age distribution among recovered birds was similar to that expected in the population at large.