Etiology of chick edema disease in Herring Gulls in the lower Great Lakes

Severe reproductive failure among fish-feeding birds on the lower Great Lakes was investigated in the early 1970s. Examination of Lake Ontario and Lake Erie Herring Gull chicks at hatching showed signs consistent with chick edema disease and thus with the presence of a chick edema factor. Subsequent microcontaminant analysis of stored eggs revealed the presence of 2,3,7,8-TCDD at concentrations that could account for the poor reproductive success and the signs of chick edema disease.