The Rumsfeld Paradigm: Knowns and Unknowns in Characterizing Habitats Used by the Endangered Sharp-tailed Snake, Contia tenuis, in Southwestern British Columbia


  • Shannon F. Wilkinson Department of Biology, University of Victoria, P.O. Box 3020 STN CSC, Victoria, British Columbia V8W 3N5
  • Patrick T. Gregory Department of Biology, University of Victoria, P.O. Box 3020 STN CSC, Victoria, British Columbia V8W 3N5
  • Christian Engelstoft Alula Biological Consulting, 1967 Nicholas Road, Saanichton, British Columbia V8M 1X8
  • Kari J. Nelson Ecosystems Branch, British Columbia Ministry of Environment, P.O. Box 9338 STN PROV GOVT, Victoria, British Columbia V8T 5J9



Sharp-tailed Snake, Contia tenuis, habitat, British Columbia


The Sharp-tailed Snake, Contia tenuis, has a small and highly fragmented range in British Columbia, where it is considered endangered. Known sites are few in number and generally small in spatial extent; numbers of snakes apparently are correspondingly low. Furthermore, most known sites for the species are on private lands in areas that are fairly heavily developed or being developed. Thus, the species is under serious threat of habitat alteration or loss. Although land stewardship has been a valuable conservation tool in this case, we also need to identify the key habitat requirements of Sharp-tailed Snakes to identify potential new sites, modify former or potential ones, or even create new ones. In this study, we compared sites known to harbour Sharp-tailed Snakes with those that seemed subjectively similar and therefore potentially suitable. We also compared these known and potential sites with randomly chosen nearby locations. Variability of most measured features was high, both within and among site/location categories. Nonetheless, we found significant differences between known and potential sites and between those locations and random ones. Overall, locations known to be used by snakes had a more southerly aspect, more rock cover, shallower soil and litter, and less shrub cover than other sites. This study was constrained by the small number of known sites for Sharp-tailed Snakes in southwestern British Columbia, making our conclusions suggestive rather than definitive. Future work should incorporate additional variables. It also might be useful to undertake comparative habitat studies elsewhere in the range of the Sharp-tailed Snake where it is more common.