1. Cetacean Ecology and Acoustics Laboratory, School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
2. School of Environment and Science, Griffith University, Gold Coast, Queensland 4222, Australia
3. Centre for Social Learning and Cognitive Evolution, and Sea Mammal Research Unit, School of Biology, University of St Andrews, St Andrews, Fife KY16 9TH, UK