Karl W. Larsen

Dept. Natural Resource Sciences, Thompson Rivers University
The use of communal denning sites (‘hibernacula’) by northern rattlesnakes in BC is a well documented phenomenon.   Emergence from hibernation in the spring (egress) is followed by often-lengthy migrations to summer foraging grounds, with a return to the same denning sites (ingress) occuring in autumn.  Presumably, the cues used by these snakes to time these events are the result of natural selection occuring over long periods of time, as making a mistake (i.e. departing too early or returning too late) could have dire consequences on the fitness of individuals.  Rapid climate change has the potential to alter the conditions under which these dispersal tactics have evolved, with short or long-term consequences to the snakes.  I will outline a new project started this fall where a consortium of academic, government, First Nations and public researchers are using wildlife cameras and temperature dataloggers to monitor the timing of ingress and egress at a number of rattlesnake dens, including several within BC protected areas.   In part, this project was initiated in response to an event recorded in 2017 that broke our stereotypic model of rattlesnake denning behaviour.  I will present the preliminary results obtained from our initial work this autumn, and discuss the range of values asssociated with monitoring rattlesnake denning behaviour.