1. Hein van Grouw, Bird Group, Natural History Museum, Akeman Street, Tring, Herts. HP23 6AP, UK, e-mail: .
2. Germán Hernández-Alonso, Center for Evolutionary Hologenomics, The Globe Institute, Univ. of Copenhagen, DK-1353 Copenhagen, Denmark, e-mail: .
3. Emily Cavill, Center for Evolutionary Hologenomics, The Globe Institute, Univ. of Copenhagen, DK-1353 Copenhagen, Denmark, e-mail: .
4. M. Thomas P. Gilbert, Center for Evolutionary Hologenomics, The Globe Institute, Univ. of Copenhagen, DK-1353 Copenhagen, Denmark, e-mail: