1. Canary Islands' Ornithology and Natural History Group (GOHNIC), La Malecita s/n, 38480 Buenavista del Norte, Tenerife, Canary Islands, Spain
2. Department of Evolutionary Ecology, Estación Biológica de Doñana (CSIC), Avda. Américo Vespucio 26, 41092 Seville, Spain and Canary Islands' Ornithology and Natural History Group (GOHNIC), La Malecita s/n, 38480 Buenavista del Norte, Tenerife, Canary