1. Chivian, E. and A. Bernstein (eds.)  2008. Sustaining life: How human health depends on biodiversity. Center for Health and the Global Environment. Oxford University Press, New York.

2. Ibid. and Thomas, C. D., A. Cameron, R. E. Green, M. Bakkenes, L. J. Beaumont, Y. C. Collingham, B. F. N. Erasmus, M. Ferreira de Siqueira, A. Grainger, Lee Hannah, L. Hughes, Brian Huntley, A. S. van Jaarsveld, G. F. Midgley, L. Miles, M. A. Ortega-Huerta, A. Townsend Peterson, O. L. Phillips, and S. E. Williams. 2004. Extinction risk from climate change. Nature 427: 145–148.

3. Endangered Species. 2009. In Encyclopædia Britannica. Available in Encyclopedia Britannica Online at

4. Chivian and Bernstein 2008, citing IUCN.

5. Wildlife crisis worse than economic crisis. 2009. Press release.

6. Wake, D. B. and V. T. Vredenburg. 2008. Are we in the midst of the sixth mass extinction? A view from the world of amphibians. Proceedings of the National Academy of Sciences of the United States of America 105: 11466–11473.

7. McCallum, Malcolm L. 2007. Amphibian decline or extinction? Current declines dwarf background extinction rate. Journal of Herpetology 41(3): 483–491. Copyright Society for the Study of Amphibians and Reptiles.


9. Jelks, H. J., S. J. Walsh, N. M. Burkhead, S. Contreras-Balderas, E. Díaz-Pardo, D. A. Hendrickson, J. Lyons, N. E. Mandrak, F. McCormick, J. S. Nelson, S. P. Platania, B. A. Porter, C. B. Renaud, J. J. Schmitter-Soto, E. B. Taylor, and M. L. Warren, Jr. 2008. Conservation status of imperiled North American freshwater and diaddromous fishes. Fisheries 33(8): 372–407.

10. Klappenbach, L. 2007. How many species inhabit our planet? Guide to Animals.

11. Tilman, D., R. May, C. L. Lehman, M. A. Nowak. 1994. Habitat destruction and the extinction debt. Nature 371:65–66.


White-headed lemur photo courtesy Flickr Commons/Frank Vassen