1. aComparative Cognition, Messerli Research Institute, University of Veterinary Medicine Vienna, Medical University Vienna, University of Vienna, Veterinaerplatz 1, 1210 Vienna, Austria
2. bMax Planck Institute for Ornithology, Eberhard-Gwinner-Straße, 82319 Seewiesen, Germany
3. cResearch Center for Biology, Indonesian Institute of Sciences, Jl. Raya Jakarta - Bogor Km.46 Cibinong 16911 Bogor, Indonesia