Massasauga release sites receive passing grade from “inspector” snakes…again!

An eastern gartersnake (Thamnophis sirtalis sirtalis) spending the winter of 2019/20 in an artificial hibernaculum at the Ojibway Prairie Provincial Park. Photograph was taken with a flexible borescope camera.

The primary goal of the Ojibway Prairie Reptile Recovery (OPRREC) program is to recover the Ojibway Prairie population of eastern massasauga rattlesnakes – a genetically, ecologically and geographically distinct Canadian population of this endangered species.

Our long-term goal includes conservation translocations with conservation-bred animals. These translocations have been attempted with massasaugas, however, the lack of successful techniques and high overwinter mortality has limited our progress. To increase success, we are using the data obtained from our hibernation habitat study begun in 2015 to identify release sites that include suitable overwintering habitat, essentially flood-free areas with animal burrows that allow snakes to descend deep enough under ground to avoid freezing and stay moist.  We are now well into the second phase of the project where we are evaluating those release sites with live snakes, following an approach approved by a university animal care committee.

We were pleased with the results of year one of the release site evaluation when an overwhelming 95% (20/21) of our snakes survived!  In the fall of 2019 we installed ten artificial hibernacula, similar to crayfish burrows where snakes naturally like to hibernate, at three proposed release sites, and placed 21 wild gartersnakes (Thamnophis sirtalis sirtalis) inside for the winter. We chose gartersnakes as a surrogate species for massasaugas because they hibernate in the same features and are not a species at risk. The survival of these “inspector” snakes confirmed that our habitat study had identified areas with suitable overwintering conditions.

Adult female eastern gartersnake (Thamnophis sirtalis) immediately after being removed from an artificial hibernaculum at Ojibway Prairie Provincial Park, in spring 2020, held by a WPC volunteer.

Due to the very successful first year, we expanded the study. We built and installed an additional eight artificial hibernacula, and hibernated over twice as many snakes across six distinct release sites. We placed 54 eastern gartersnakes, both captive-reared and wild, in hibernation in November 2020 and have been monitoring the snakes with a borescope camera every two weeks.

I am elated to announce that on our last check we confirmed 51 snakes remain alive in the artificial hibernacula – a 91% survival rate so far! Winter mortality is a natural occurrence in snakes and our results are at the high end of survival rates recorded in other gartersnake studies (i.e., Thamnophis spp.).

Our combined results from both years suggest a preliminary survival rate of 92%, which shows a lot of promise for successfully translocating massasaugas and helping restore the population. The next step is to conduct a trial with massasaugas. Until then however, we are thankful to the gartersnakes of winter ’19 and ‘20 for their contribution to massasauga recovery!

Jonathan Choquette, OPRREC Lead Biologist, installing a new artificial hibernaculum in fall 2020 as part of a project to evaluate massasauga release sites.