Summary 1.Although experimental studies show that organochlorines (OC) can affect bird behaviour, field assessments are invariably confounded by ecological differences between contaminated and uncontaminated sites. The behaviour of individual birds in the field has rarely been related to the contaminant burden. 2. We examined individual patterns of incubation and nest-site attentiveness in relation to OC burden, measured as polychlorinated biphenyl (PCB) concentration in the blood, of 27 glaucous gulls Larus hyperboreus in two breeding areas at Bear Island, in the north-eastern Atlantic. 3. Blood PCB concentrations ranged from 52 ng g − 1 to 1079 ng g − 1 (wet weight). There were significant differences between the two breeding areas, and females had significantly lower concentrations than males. 4. Gull behaviour differed significantly between breeding areas and sexes independently of PCB. Females incubated more than males (54% vs. 46%) but spent more time away from the nest site than males, both overall (23% vs. 12%) and when not incubating (50% vs. 21%). They were also absent for longer periods (4·5 vs. 2·8 h). Moreover, length of incubation bouts (6·4 vs. 4·4 h), the amount of time absent from the nest site when not incubating (51% vs. 25%) and length of absences (5·6 vs. 1·8 h) differed between breeding areas, probably due to different feeding specializations. 5. After controlling for these area and sex effects, the proportion of time absent from the nest site when not incubating, and the number of absences, were both significantly related to blood concentration of PCB. 6. Increased absence from the nest site in individual glaucous gulls with high blood concentrations of OC suggests effects on reproductive behaviour. We speculate that endocrine disruption or neurological effects might be involved, leading to increased energetic costs during incubation and reduced reproductive output.

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Immune function and organochlorine pollutants in arctic breeding glaucous gullsBustnes, JO; Hanssen, SA; Folstad, I; Erikstad, KE; Hasselquist, Dennis; Skaare, JU General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. (PCB 101, 99, 118, 153, 138, 180, and 170). There were significant or near significant positive relationships (0.1 Ͼ p Ͼ 0.001) between most persistent OCs and the levels of heterophils in the blood for both sexes in 1997 and for male gulls in 2001. Similarly, levels of all persistent OCs and lymphocytes were positively related (0.1 Ͼ p Ͼ 0.001) in both sexes in 1997. This suggests that OCs are causing alterations to immune systems, which may decrease their efficiency and make the birds more susceptible to parasites and diseases. In female gulls, the antibody response to the diphtheria toxoid was significant and negative for HCB (p Ͻ0.01) and weaker, but significant, for oxychlordane (p Ͻ0.05), suggesting that OCs were causing an impairment of the humoral immunity. Various OCs have been linked to negative effects in our study population, including decreased survival and reproduction, and this study suggests that such compounds also affect immune status and function. Immune Function and Organochlorine Pollutants in Arctic Breeding Glaucous Gulls

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