Reduction of Organochlorine Residues in Goshawk Eggs (Accipiter gentilis) from Northern Germany (1971-2002) and Increasing Eggshell Index

摘要

We investigated unhatched eggs (n = 57) of Goshawks (Accipiter gentilis) from the period 1988-2002 and compared them with eggs (n = 134) from 1971-1978. Mean concentrations of PCBs, sum DDT and HCB in the earlier period were (mg kg~(-1) lipid weight) 50.1, 126.6, and 117.7, while the values from the later period were statistically significantly lower: 27.7, 4.1, 0.1, respectively. Nevertheless, the concentration of PCB relatively constant during the last 8-10 years. The variability of residues was lower within clutches than among clutches. No age-dependent accumulation in eggs could be demonstrated. A statistically significant lower shell index was measurable for the period 1971-1978, while this index during 2001-2002 was relatively high as it was during the late 18~(th) century. We are suggesting a threshold value for effect concentrations on shell index. Residues of the DDT-group had an influence on the number of fledged young per nest site.