Relationships between POPs and baseline corticosterone levels in black-legged kittiwakes (Rissa tridactyla) across their breeding cycle.

Chronic exposure to persistent organic pollutants (POPs) in wildlife might alter the response to environmental changes through interference with the regulation of stress hormones. Here, we examined the relationship between blood concentrations of several POPs and baseline plasma corticosterone levels in the black-legged kittiwake (Rissa tridactyla) during three distinct periods in the breeding season. The concentrations of POPs and corticosterone increased, whereas body mass decreased progressively from the pre-laying period to the incubation and the chick rearing period. ∑PCB (polychlorinated biphenyls) correlated positively with the baseline corticosterone levels during the pre-laying period, which might suggest that PCBs affect the regulation of corticosterone. However, this relationship was not found during the incubation or the chick rearing period. Possible explanations are discussed with emphasis on how total stress/allostatic load is handled during different periods and conditions.