1 Netherlands Institute of Ecology, Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands; Vrije Universiteit Amsterdam, Department of Ecological Sciences - Animal Ecology, Amsterdam, The Netherlands. Electronic address: j.harvey@nioo.knaw.nl.
2 Institute of Ecology and Evolution, University of Bern, Baltzerstrasse, 63012, Bern, Switzerland.
3 Vrije Universiteit Amsterdam, Department of Ecological Sciences - Animal Ecology, Amsterdam, The Netherlands.