Garter Snake

Common Garter Snake

Thamnophis sirtalis

Common Garter Snake Thamnophis sirtalis Head Scales


IdentificationCommon Garter Snake Thamnophis sirtalis

The most commonly seen snake species in New England and Eastern Canada is the Common Garter Snake Thamnophis sirtalis. The pattern and coloration can vary from one individual to another and with the age of the snake, but a mid-dorsal yellow stripe and side stripes on the 2nd and 3rd row of scales are common. The rest of Common Garter Snake Thamnophis sirtalis label middorsal stripethe body can be dark green, olive, or khaki colored, with the ventral side being lighter in coloration. The pattern and coloration is more vivid in juveniles, and there are some melanistic (all black) individuals. They have a single anal plate and their scales are keeled.


At maturity, garter snakes can reach 24-40”.


They produce mating balls and give birth to live young. Scientists are currently studying the use of pheromone trails that lead males to females.


  • Active during day
  • Some individuals may be aggressive, others are docile
  • Usually all will become docile after a period of time
  • May release musk when caught

Life Span

  • 10 years


  • Insects, small invertebrates, worms, salamanders, frogs, toads


Garter snakes hibernate with many other individuals in their den. Some northern populations may stay in their dens for 6 months.


  • woodland
  • fields on edges of forests
  • edges of ponds
  • stone walls
  • like sunny areas near forested land
  • scrub (low brush)
  • have been seen at elevations of 8000’ (2,450 m)


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