1. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7000, Australia
2. BirdLife Tasmania, GPO Box 68 Hobart, Tasmania 7001, Australia
3. Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, New South Wales 2088, Australia
4. Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia