LOVE, O.P.; SHUTT, L.; BIRD, D.M.: Dietary PCB-induced impairment of the adrenocortical response in captive American kestrels

We examined the effects of dietary exposure to PCBs on the adrenocortical response in American kestrels (Falco sparverius). Nine captive male American kestrels previously exposed to elevated levels of a mixture of PCB congeners (1248:1254:1260; 1:1:1) in their diet underwent a standardized capture, handling and restraint protocol designed to result in an increase in circulating corticosterone. This protocol has been applied to a wide range of avian species and was used here to evaluate the response of PCB-exposed and control kestrels to a defined physical stressor. Baseline and maximum levels of corticosterone were significantly lower in PCB-exposed birds when compared with control birds of the same age. PCB birds also had significantly lower corticosterone levels as time increased during the response as compared with control birds, independent of body condition. These results support several recent studies which report decreased levels of circulating corticosterone in PCB-exposed birds. Furthermore, the results presented here provide the first evidence that exposure to environmentally relevant levels of PCBs can impair avian HPA axis function, possibly increasing the susceptibility of birds to environmental stressors such as severe weather and predatory and human disturbance.