Individual female common cuckoos Cuculus canorus lay constant egg types but egg appearance cannot be used to assign eggs to females

A. Moksnes (correspondence), E. Røskaft, S. Skjelseth, and B. G. Stokke, Department of Biology, Norwegian University of Science and Technology, NTNU, Realfagbygget, N-7491 Trondheim, Norway. E-mail: [email protected]. G. Rudolfsen, Department of Zoology/ Ecology, University of Tromsø, N-9037 Tromsø, Norway. O. Kleven, Natural History Museum, Department of Zoology, University of Oslo, P.O. Box 1172 Blindern, N-0318 Oslo, Norway. H. Lisle Gibbs, Department of Evolution, Ecology, and Organismal Biology, 1735 Neil Avenue, Ohio State University, Columbus, Ohio, USA. M. Honza, Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, 60 365 Brno, Czech Republic. B. Taborsky and M. Taborsky, Institute of Zoology, Department of Behavioural Ecology, University of Bern, CH-3032 Hinterkappelen, Switzerland. Y. Teuschl, Zoologisches Museum, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland. W. Vogl, Konrad Lorenz-Institut für Vergleichende Verhaltensforschung, A-1160 Vienna, Austria.