1. Swiss Ornithological Inst. Sempach Switzerland
2. RSPB Centre for Conservation Science Sandy UK
3. Museum and Inst. of Zoology, Polish Academy of Sciences Warsaw Poland
4. Dept of Evolutionary Biology and Environmental Studies, Univ. of Zurich Zurich Switzerland
5. UK Centre for Ecology and Hydrology Wallingford UK
6. Division of Conservation Biology, Inst. of Ecology and Evolution, Univ. of Bern Bern Switzerland
7. Southampton UK
8. Birdlife Switzerland Zurich Switzerland
9. Dept of Biology, Univ. of Marburg Marburg Germany
10. Laboratory of Forest Biology, Wrocław Univ. Wrocław Poland