Le Viol, I., Jiguet, F., Brotons, L., Herrando, S., Lindström, Å., Pearce-Higgins, J.W., Reif, J., Van Turnhout, C. & Devictor, V. 2012. More and more generalists: two decades of changes in the European avifauna. Biology Letters doi:10.1098/rsbl.2012.0496