1. International Avian Research; Am Rosenhügel, 59 A-3500 Krems Austria
2. United States Geological Survey; Patuxent Wildlife Research Center; Laurel MD 20708 USA
3. RSPB; Scotland; Old School; Crossmichael Castle Douglas DG7 3AP UK
4. Scottish Raptor Study Group; 58 Meadowbank Rd Kirknewton West Lothian EH27 8BS UK
5. School of Natural Resources and Environment; University of Florida; Gainesville FL 32611 USA
6. Department of Wildlife Ecology and Conservation; University of Florida; Gainesville FL 32611 USA
7. Conansknowe; Kirkton Dumfries DG1 1SX UK
8. Centre for Ecology and Hydrology; Benson Lane Crowmarsh Gifford Wallingford OX10 8BB UK