Cracking the conundrum of communal denning through an assessment of hibernacula features and availability


McKelvey, Veronica

vmckelvey@tru.ca


Isaac, Leigh Anne

Department of Natural Resource Science

Thompson Rivers University

Kamloops, British Columbia Canada


Isaac, Leigh Anne

BC Provincial Government

Kimberly, British C Canada


Larsen, Karl W.

Department of Natural Resource Science

Thompson Rivers University

Kamloops, BC Canada


Due to the harsh weather that winter brings in temperate regions, snakes must locate and use dens that meet their requirements for survival. Within higher latitudes, snakes increasingly den communally (i.e., congregate to overwinter). Why communal denning occurs is still unclear: One leading theory proposes that this phenomenon results from decreased availability of adequate overwintering habitat. However, other potential explanations could include specific life history characteristics, physical constraints, migration pathways that may not overlap with other available dens, and environmental requirements of different species. The overall goal of this proposed research is to investigate the communal overwintering behaviour of the Western Rattlesnake (Crotalus oreganus) and the apparent mix of communal and solitary behaviour of the sympatric Great Basin Gophersnake (Pituophis catenifer deserticola) and Western Yellow-bellied Racer (Coluber constrictor mormon) in south-central British Columbia. To do so, the variation in environmental characteristics and availability of atypical and typical hibernacula used for communal and solitary denning species or conspecifics is being quantified. For this research, we are defining ‘typical dens’ as those found within rocky outcrops at the base of a rockface, while ‘atypical dens’ include a range of other features. Another potential explanation for communal denning is being investigated by measuring the physical attributes of the snakes to determine if there are constraints (i.e., head size, mid-body size) that limit the accessibility of typical versus atypical den sites. A minimum of 24 dens (14 believed to be typical and 10 atypical) have been discovered and are currently being assessed. This research will further our understanding of the communal overwintering behaviour in northern snakes and uncover important habitat features that characterize dens and their availability on the landscape.