1. The Charles Perkins Center,
2. School of Biological Sciences, and
3. Centre National de la Recherche Scientifique (CNRS),
4. Université de Toulouse (UPS), Centre de Recherches sur la Cognition Animale, 31062 Toulouse, France;
5. Department of Zoology, Oklahoma State University, Stillwater, OK 74078;
6. Faculty of Veterinary Science, The University of Sydney, NSW 2006, Australia;, , ,