Common Garter Snake (Thamnophis sirtalis)


Class: Reptilia
Order: Squamata
Family:    Colubridae
Size:    Length: 18 to 51 inches (46 to 131 cm)
Weight: Unknown
Diet: Earthworms, frogs, toads, tadpoles, insects, salamanders and sometimes mice
Distribution: USA, Canada, Mexico
Young:  10 to 30 live young
Animal Predators:  Crows, ravens, weasels, minks, raccoons, foxes, ground squirrels, hawks and owls
IUCN Status: No special status
Terms: No special terms
Lifespan: 6 to 10 years in captivity



·         Garter snakes are often mistakenly called garden snakes.

·         The scientific name “Thamnophis sirtalis” means “bush snake like a garter” in Latin. 

·         Common garter snakes are the most widespread species of snakes in North America.



Garter snakes are named for the bright pattern of stripes (usually yellow) that resemble garters and run the length of their bodies (black, green or brown). Garter snakes have four rows of teeth which point backwards in their upper jaws. The outer two rows of teeth work independently of each other while the middle rows go back and forth, helping these snakes work large prey slowly down their throats. There are many different types of garter snakes in North America, but as the name suggests, these are the most common ones.



Common garter snakes can live in a wide variety of habitats, including woods, agricultural areas, wetlands and residential areas. Because they can survive colder areas than most snakes, common garter snakes are the only snakes living in the Northwest Territories. They are found from the Atlantic to Pacific coasts of North America except for the desert regions of the southwest.


Feeding Habits

Prey is detected by swallowing scent trails—the snake’s red, black-tipped tongue flickers in the air testing for scents. Prey is swallowed whole, so garter snakes do not actually chew but use the teeth to move the prey in their mouths. After swallowing, snakes will have a bulge in their middles that may remain there for several days. They prey mainly on earthworms, frogs, toads, tadpoles, insects, salamanders and sometimes mice.



Mating season begins in early spring following hibernation, with mating also sometimes occurring again in the fall. The female mates with many males at once and the male plays no role in raising the young. In summer, females will give birth to as many as 80 live young (as opposed to eggs like some other snakes) but usually the litter is 10 to 25. The young snakes are five to nine inches in length at birth and do not become fully mature for two to three years.



Unlike many other snakes, garter snakes are not nocturnal. They are relatively harmless snakes that will head quickly in the other direction when they encounter humans. Garter snake bites are not poisonous, but they will bite if captured and release a foul odour. Garter snakes usually live near water and will enter it when alarmed or threatened. They hibernate in large groups of hundreds or thousands inside abandoned burrows, rock crevices or even the foundations of old buildings. 



Although common garter snakes are generally not of conservation concern, a subspecies, the San Francisco garter snake, is on the U.S. Endangered Species List.