Effect of relocation on a threatened snake species in British Columbia

Background/Question/Methods

Habitat loss threatens the Great Basin gophersnake (Pituophis catenifer deserticola) (COSEWIC 2013; Woo-Durand et al. 2020), a grassland-adapted colubrid snake found in isolated pockets of British Columbia (Haney and Sarell 2007). In British Columbia, our currently limited knowledge of the natural history of northern populations of gophersnakes makes designing management plans for the species challenging. When snake habitat is disturbed, a common management practice is to relocate animals. In 2020, an industrial project disturbed a large snake den in a protected grassland. Over 50 gophersnakes were removed from the site and relocated to a new den. This event created a unique opportunity to study the effect of relocation on a large population of gophersnakes. My research asks the question: how does relocation affects the survival, reproduction, and movement of a population of gophersnakes during the summer active season? Because gophersnakes demonstrate den and egg-laying site fidelity, I predict that relocated snakes will on average take longer to find egg-laying sites and dens, and to establish home ranges compared to a reference population of conspecific snakes. Because snake predation and road mortality are positively correlated with movement (Bonnet et al. 1999), I hypothesize that relocation will increase mortality rates of gophersnakes.

Results/Conclusions

In the 2021 summer season, I conducted radiotelemetry on a sample population of 32 Gophersnakes (average of 117 days tracked) in the Lac du Bois protected grassland. At every snake location GPS coordinates were recorded. Once published, this dataset of GPS coordinate locations will represent one of the largest radiotelemetry sample populations of Gophersnakes in Canada. Of the 17 relocated snakes that were tracked in 2021 using radiotelemetry, 10 survived to denning and 3 died during the active season, the outcome of 4 snakes could not be determined. Of the 15 reference snakes that were tracked in 2021, 10 survived to denning and 1 died during the active season, the outcome of 4 snakes could not be determined. There was no significant difference in mortality between the relocated and reference populations (𝜒2 (1) = 0.84, p = 0.36). In 2022, I will conduct a second summer of radiotelemetry on the same population of snakes. I will also examine the multi-year fidelity of both species to egg-laying and denning sites. This research project will provide valuable insight into the management of at-risk snake habitat, as well as lay the groundwork and set a precedent for future long-term studies on gophersnakes.