1. Conservation Biology Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
2. Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen 0, Denmark.
3. Center for Applied Biodiversity Science, Conservation International, 1919 M Street NW, Suite 600, Washington, DC 20036, USA.
4. Wildlife Conservation Society of Tanzania, Pamba House, Post Office Box 312, Morogoro, Tanzania.
5. Biogeography and Conservation Laboratory, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK.