Environmental Contaminants in Liver and Kidney of Free-Ranging Northern Goshawks (Accipiter gentilis) from Three Regions of Germany

The northern goshawk (Accipiter gentilis) is a top predator in the terrestrial food web of large parts of the Holarctic. Due to its sedentary nature and well-investigated feeding ecology, it represents the most suitable bird of prey species in continental Europe for monitoring environmental pollutants. We analyzed the levels of organochlorine pesticides, polychlorinated biphenyls (PCB), and nonessential heavy metals in organ samples of 62 free-ranging northern goshawks found dead or injured in Germany from 1995 to 2001. Our results indicate significant differences in the contaminant burden of northern goshawks between three regions in Germany. Presumably, these differences were caused by different application periods and legislative restrictions before the German reunion, especially for the use of DDT in agriculture and forestry. Extraordinarily high residues of PCBs and DDE, the main metabolite of DDT, were found mainly in livers of northern goshawks inhabiting Berlin. Body condition is highly negatively correlated with the contamination level of the individual, especially for the persistent and lipophilic organochlorines and for mercury. PCB concentrations in hepatic tissue increase rapidly with age, and birds in their first summer had significantly lower levels than birds in their first winter or older. Adult female northern goshawks from Berlin had significantly higher hepatic concentrations of most of the higher-chlorinated PCBs and of cadmium than males from the same region. Cadmium residues were in general higher in renal tissue than in hepatic tissue, and cadmium levels in kidneys increased with age. Lead concentrations indicative of acute lead poisoning were detected in one bird and suggested in two others. All other heavy metal concentrations were low and represent background levels for birds of prey in Germany.