1. Animal Demography Unit, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
2. Marine Research Institute, University of Cape Town, Cape Town, South Africa
3. School of Biological Sciences, Plymouth University, Plymouth, Devon, UK
4. Southern African Foundation for the Conservation of Coastal Birds, Bloubergrant, Cape Town, South Africa
5. Branch Oceans and Coasts, Department of Environmental Affairs, Cape Town, South Africa