As the summer ends in Southwestern Ontario, WPC’s Ojibway Prairie Reptile Recovery team is wrapping up it’s first year of a new recovery project. Many see eastern gartersnakes as a common species which emerge from their hibernation sites in the spring and get right to work with mating as large, tangled masses of snakes called mating balls. However, if you are in the Sarnia or Windsor areas of Ontario there may be another similar looking snake easily mistaken for eastern gartersnakes – the Butler’s gartersnake. Despite its similar appearance to the eastern gartersnake, the smaller, more secretive, Butler’s gartersnake is quite different.

Gartersnake mating ball. Can you count how many snakes are here? Photo: Jeff Mitton

The Species

The Buter’s gartersnake (Thamnophis butleri) can easily be mistaken for other similar looking snakes in Ontario, such as northern ribbon snakes (T. sauritis) or the previously mentioned eastern gartersnakes (T. sirtalis). Smaller than the other Thamnophis snakes in Ontario, with a shorter body and narrower head and neck, the Butler’s gartersnake is often overlooked and misidentified. The best way to tell the difference between these three striped snakes is the location of the lateral stripes that run along the side of the body, in Butler’s gartersnakes the lateral stripe is centered on the 3rd scale row. Take a look at our video on Butler’s gartersnake stripes here for more details.

Butler’s gartersnake (Thamnophis butleri) lateral stripe. Note the stripe centered on scale row 3, and partially covering scale rows 2 and 4. Photo: Cory Trowbridge

Butler’s gartersnakes are also more selective in their diets and habitat compared to some of the other Thamnophis snakes. They prefer open habitats such as tallgrass prairies, old fields, and other large grassy areas located close to wet or damp environments. Also, unlike the more varied diet of the eastern gartersnake, the Butler’s gartersnake feeds almost exclusively on earthworms. Interestingly, Butler’s gartersnakes are believed to have fed predominantly on leeches prior to the introduction of European earthworms by early settlers. Presumably, as it shifted its diet toward earthworms, the Butler’s gartersnake became less dependant on wetland habitats than it was historically.

The Threats

Even after causing a shift in the Butler’s gartersnake’s diet, humans continue to alter the lives of these snakes. The loss of tallgrass prairies and the removal of open grassy areas has led to rapid disappearance of Butler’s gartersnakes across their southwestern Ontario range. As a result of habitat loss and the extirpation of local subpopulations, the Butler’s gartersnake is now an endangered species in Canada. For example, this species was once present in a continuous band stretching from the mouth of the Detroit River near Amherstburg to the head of the St. Clair River near Sarnia. Now, Butler’s gartersnakes are mostly restricted to clusters of subpopulations in the Sarnia and Windsor areas, which are genetically isolated from each other. Urban, industrial and agricultural developments in these areas have also further fragmented and isolated remaining subpopulations, increasing the likelihood of local extirpations. Given this bleak outlook, Wildlife Preservation Canada has decided to ramp up its efforts in the hopes of improving the status of the Butler’s gartersnake before its too late.

The Recovery Project

In 2022 Wildlife Preservation Canada’s Ojibway Prairie Reptile Recovery (OPRREC) team started undertaking a new Butler’s Gartersnake Recovery Project. This project will contribute towards the recovery of Butler’s gartersnakes by improving our understanding of how habitat fragmentation impacts the species, implementing habitat enhancement activities to increase the amount of available habitat and reconnect fragmented populations, and improving translocation techniques to recover extirpated subpopulations. Along with this new recovery effort, the OPRREC team also welcomed a new Project Biologist, Cory Trowbridge, to help manage and plan the project. Cory comes with a background in reptile and amphibian population ecology and firsthand experience with Butler’s gartersnakes.

Cory Trowbridge and the rest of the OPRREC team look forward to providing updates on the Butler’s Gartersnake Recovery Project in the near future.

Literature Cited
  • Powell, Robert, et al. “Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America.” Amazon, Houghton Mifflin Harcourt, 2016.

Cory Trowbridge

Project Biologist – Ojibway Prairie Reptile Recovery

Cory is the project biologist on the recovery of the Butler’s gartersnakes as part of the Ojibway Prairie Reptile Recovery Program. Cory’s past research focused on the ecology of reptiles and amphibians around energy facilities. He has worked with a variety of reptile and amphibian species across Ontario and completed his MSc at Laurentian University in 2020.