ABSTRACT
This chapter collates more recent findings of Polychlorinated biphewnyl (PCB), PCDD, and PCDF toxicity in wild birds, to propose effect thresholds and identifies high risk species groups. Application of new statistical approaches, and molecular and ecological methodologies have refined our knowledge of metabolic and exposure pathways for wild birds. Although the focus of many studies of PCB and PCDD effects in wild birds has been reproduction, a few have also attempted to measure chronic effects on adult survival in field by investigating adult return rates in species exhibiting strong nestor natal-site fidelity. Episodic food, thermal and disease stresses in wild birds will continue to occur, possibly more frequently with climate change, and it is important to better understand synergistic effects exerted by PCBs and PCDDs. The traditionally monitored biochemical markers of PCB and PCDD impacts, namely porphyria, vitamin A status, thyroid function, and immune function, may provide some indications of vulnerability of adult wild birds to ecologically mediated stress events.
