1. Department of Conservation Biology; Estación Biológica de Doñana (CSIC); Avda. Américo Vespucio s/n; E-41092; Sevilla; Spain
2. Department of Ecological Modeling; UFZ-Centre for Environmental Research; D-04301; Leipzig; Germany
3. Socotra Archipelago Conservation and Development Programme; P.O. Box 16494; Sana'a; Yemen
4. BirdLife International; Wellbrook Court; Girton Road; Cambridge; CB3 0NA; UK