Our Wild Neighbors

Common Garter Snake

Thamnophis sirtalis

Well adapted to urban parks in all provinces except Newfoundland

Image of a common Garter Snake, seen from in front while coiled up.

Description of the animal

  • Three yellow or brownish stripes on its back and flanks.
  • Length: up to 1.24 metre long.
  • Scales divided into 19 rows on the central part of its body.
  • Colour patterns vary by region.
  • Usually dark brown or black. The Common Garter Snake can also be orange, red, white, bluish, or greenish in colour.
  • Belly is yellow or greyish, at times red.

Habitat and needs

  • Likes almost any environment, even those that have been disturbed (work sites, rock falls, fallow land, clear-cut areas, burnt landscapes). It is partial to the banks of ponds, lakes, and rivers.
  • Finds shelter under rocks, planks of wood, piles of scrap metal, or any other flat object littering the ground. It also likes to hide in dead trees.
  • Depends on external heat sources to maintain its body temperature. The Common Garter Snake spends lots of time warming itself on and under stones.
  • Mates in a group. In the spring, when the female leaves its nest, about 20 males surround it, ready to mate with it. The female carries its eggs in a ventral pouch.
  • They are excellent swimmers and good climbers.
  • Eats earthworms, slugs, small fish, tadpoles, salamanders, and, especially toads and frogs. At times, it devours insects, spiders, tiny birds, and young rodents.
  • Swallows large-sized prey. It opens its jaws wide and pushes the victim to the back of its throat with its teeth. It then contracts its muscles to push its prey towards its stomach.
  • Hibernates in various locations: underground (below the frost line), in a crevice, under a stone pile, in a burrow, in an old well, or in an old foundation.
  • Defends itself by rolling into a ball. The Common Garter Snake puffs itself up and shows the bluish skin between its scales. If it is caught, it struggles by twirling and releasing a foul-smelling liquid. It doesn’t hesitate to bite.
  • Detects the odours of its prey, adversaries, and partners with its tongue.
  • More resistant to toxic products and the cold than amphibians.

Relationship

  • The Common Garter Snake is often run over by cars while it is warming itself on pavement.
  • It helps control populations of insects, molluscs, and small rodents.
  • It can startle people who discover it under a stone or in flowerbeds.
  • Scientists take an interest in it, especially to study its resistance to certain poisons and its endurance to the cold.
  • It is victimized by cats and dogs.

Living with them

  • Avoid picking it up: some are more likely than others to bite.
  • If you like having the Common Garter Snake around, provide it with hiding places, like stones, pieces of wood, or a variety of natural or artificial debris.
  • To prevent the Common Garter Snake from hiding in a stack of wood, put wood inside before the snake’s hibernation period.

Participating cities where this animal has been seen