Complicated conservation for a far-northern rattlesnake: ecological diversity over a small peripheral range

Larsen, Karl W.

klarsen@tru.ca

Department of Natural Resource Sciences

Thompson Rivers University

Kamloops, British Columbia

CANADA

All Canadian snake species reach the northern limits of their distribution within the country, and many have limited ranges that invoke the ‘peripheral population’ concept. While the biological value of these populations long has been used as an argument for their conservation (and peripheral populations in general), the limited ranges often seen within Canada prompt fairly uniform assessments and management strategies, and a ‘one size fits all’ approach. However, in conducting detailed ecological study of the threatened Western Rattlesnake (Crotalus oreganus) over 25+ years, our research program has revealed a striking diversity of life-history traits and behaviors within the very limited Canadian range of the animal, including some that may have developed relatively recently. This variation includes migratory tactics, size at first reproduction, behavioral over short distances, and significantly different habitat use even within the same subpopulations. I will provide a synthesis of this variation, the research behind it, and the possible contributing factors (anthropogenic and natural) that may be at work. I also will outline the further complications in conservation caused by multiple layers legislation. All told, the striking differences witnessed over a ‘pocket range’ of the species are not altogether unexpected given our understanding of peripheral populations, and they suggest a blanket approach to management may be an oversimplification of a more complex problem.