Study skins of Herring Gulls (Larus argentatus) and Great Black-backed Gulls (L. marinus) collected over a period of ∼150 years in the northeastern United States were used to test the hypothesis that potential exposure to polychlorinated biphenyls (PCBs) has an effect on age-related plumage coloration. We found no changes in the average age class (as determined by plumage) of gulls collected before and after 1930 (date PCBs began to be used) and no differences in average age class in birds collected near PCB-contaminated sites versus those collected far from such sites. We found significant skews in the age distributions of birds in our sample because of an under-representation of birds of intermediate age classes, but those skews were similar in pre- and post-1930 data sets and thus likely represent sampling errors and not the effects of PCBs. There was no difference in the age distribution of gulls collected near or far from contaminated sites. Our study, albeit indirectly, shows no evidence that PCB exposure affects plumage maturation rate in piscivorous gulls.

Patrons Géographiques et Temporels du Plumage chez les Laridés en Fonction de l’\bcp\A\ecp\ge et de l’Exposition Potentielle aux Polychlorobiphényles