The contamination of German peregrine falcons (Falco peregrinus) with organochlorine (CHC) biocides and mercury (Hg) was investigated over the years 1955-2002.

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After the disappearance of the Peregrine Falcon during the DDT era, the re-colonization of Eastern Germany from 1981 was accompanied by colour-ringing of a high percentage of juveniles and systematic identification of these individuals on their later nest-sites. Before that period there were two geographically distinct subpopulations: tree-breeders in the north, and cliff-breeders in the south. We were able to restore the tree breeders’ tradition by imprinting nestlings at stick nests in forests. Today, besides cliff- and tree-breeders there are also nest-sites on buildings and lattice structures. The population is increasing including all nest-site types. Here, we analyse nesting habitat choice with respect to the natal habitat of birds. The exchange between the four nest-site types is limited. Habitat fidelity was high in birds fledged on cliffs (95%) and on buildings (81%). The sample size for lattice structures is still too low for deeper analyses. The fixation towards trees was stable only in 56% of birds, and higher for males than for females. The influx from other habitat types is very limited and hardly supports the tree breeders’ subpopulation. A growing number of tree-breeders go along with higher habitat fidelity which is stabilizing their sub-population.

No abstract