Plains Gartersnake

Thamnophis radix

Species at Risk: Sensitive

Plains gartersnakes are found chiefly in short grass prairie and aspen parkland. In Alberta they range throughout the eastern half of the province south of Cold Lake. Their most striking feature is the bold solid orange vertebral stripe. There is a lighter yellow lateral stripe on each side as well. While the background is described as an olive to brown with dark spots creating a checkerboard pattern, in Western Canada this generally blends into a largely solid black backround creating some of the most beautifully contrasting examples of the species. The ventral scales can be whitish, bluish green or grey. Females are larger than males, and total lengths of adults are from 50cm to 100cm. Mating occurs upon spring emergence from the hibernaculum. Young are born live, in a membranous sack that is broken open during parturition or immediately afterwards. This can be a prolific species and starting in July females may birth 5-40 young. As many as 92 offspring have been in a single litter. When picked up these snakes are reluctant to bite, but quick to musk. That is, they smear onto you the contents of scent glands and the cloacal in an attempt to deter a would-be predator from an otherwise tasty snack.

These snakes are habitat generalist within their range. They live near ponds, lakes, streams, marshes and dugouts, but will also stray a long distance from water. These snakes are often found in urban areas as long as enough suitable habitat persists. In addition to a water source, it is imperative that these snakes have a place to overwinter. This may be in naturally occurring sink holes, mammal burrows, rock piles or fishers among tree root systems. Plains garters feed on fish, amphibians, small mammals, worms, invertebrates and even carrion.

The plains gartersnake appears to be doing well in Alberta. There are many thriving populations and they are often seen by hikers and campers on a sunny summer day. Anecdotally gartersnakes have been decreasing in numbers. Care must be used to keep this a common species and monitoring programs need to be used to assess this decline. The biggest threats to the gartersnake are the draining of wetlands and the destruction of hibernation sites. Gartersnakes are not a protected species in Alberta but the animals and their hibernacula are under protection during the winter months while they are dormant. Unfortunately, this leaves an open window for the destruction of these sites during the summer. Snake populations without a place to spend the winter are doomed.

The Amphibians and Reptiles of Alberta by A.P.Russell and A.M.Bauer

Photo by Ian Kanda