1. Inst. of Avian Research ‘Vogelwarte Helgoland’ Wilhelmshaven Germany
2. Dept of Forest Biodiversity, Univ. of Agriculture Kraków Poland
3. U.S. Geological Survey, Northern Rocky Mountain Science Center Bozeman MT USA
4. Natural Resources Inst., Univ. of Greenwich Chatham Kent UK
5. Rothamsted Research, Harpenden Hertfordshire UK
6. Corix Plains Inst., Univ. of Oklahoma Norman OK USA
7. Inst. of Ecology and Evolution, Univ. of Bern Bern Switzerland
8. School of Biological Sciences, The Univ. of Western Australia Crawley Australia