Impacts of fencing and development of western rattlesnake (crotalus oreganus) spring movements in British Columbia

Due to increasing anthropogenic pressures, the process of natural animal migration is undergoing alterations across many different taxa. To investigate these impacts is difficult on large-scale migrations, yet small-scale migrants will provide useful and tractable systems to understand the effects of disturbance and landscape barriers on natural movement patterns and migrations. The Western Rattlesnake (Crotalus oreganus) in British Columbia is a small, migratory predator that undertakes annual spring movements from communal hibernaculum to summer hunting grounds. In this thesis, I examined changes to these migration movements in male rattlesnakes that encountered both snake exclusion fencing barriers and disturbed habitats from 2011-2016. My thesis field work included 2015 and 2016, and data from 20112014 was drawn from a long-term project database. Individuals moving through disturbed habitats or intercepted by snake exclusion fencing demonstrated shorter migration distances and reduce spring path sinuosity (more crooked routes) compared to individuals migrating in undisturbed habitats. Specifically, individuals encountering a snake fence during spring movements had shorter total spring migration path lengths and smaller home ranges. Regardless, migration distance was strongly associated with the distance individuals travelled until they first encountered human disturbance. Despite this difference, duration of the migration did not differ between rattlesnakes that encountered a snake exclusion fence, experienced other forms of disturbance, or migrated through undisturbed habitats. Overall, my work reveals the importance of looking closely at seasonal movement patterns, including migration, of smaller-scale migrants in response to abrupt and long-term landscape changes and barriers. Small-scale migrants can be used as an important indicator of landscape and community connectivity and can be used as an important reference for managing ecosystem function and health on a changing, anthropocentric landscape.