1. Dept of Zoology and Physical Anthropology, Faculty of Biology; Univ. Complutense of Madrid; José Antonio Novais, Ciudad, Universitaria ES-28040 Madrid Spain
2. San Juan Bautista 1 4B, ES-28231 Las Rozas de Madrid, Madrid Spain
3. Virgen del Camino 3 3D, ES-28911 Leganés Madrid Spain
4. British Antarctic Survey, UK, Currently at Migrate Technology Ltd.; Cambridge UK
5. Dutch Centre for Avian Migration and Demography and Dept of Animal Ecology; Netherlands Inst. of Ecology (NIOO-KNAW); PO Box 50 NL-6700AB Wageningen the Netherlands
6. Dutch Montagu's Harrier foundation, Animal Ecology Group, Groningen Inst. for Evolutionary Life Sciences, Groningen Univ.; Groningen the Netherlands