The common garter snake is highly variable in coloration across their range. In general they have a dark colored body covered with black, brown, gray or olive scales. Running down the length of their body are three lighter colored stripes in a shade of red, yellow, white, blue, greenish or brown. In some parts of their range the stripes are replaced with spots. Their chin, throat and underside are similar in color to the stripes. Some species of common garter snake do not have the stripes and are entirely dark colored. The scales are keeled.
Common garter snakes have a red tongue which is tipped with black. Their tongue is forked and appears to split at the end. This tongue is a detection device for chemicals in the air which are then processed by the Jacobson’s organ on the roof of their mouth.
The length of a common garter snake is variable between 46 and 137cm (18.1-53.9in) and an average weight is 150g (5.29oz).
The common garter snake is a carnivore. They primarily feed on insects, fish, crayfish, amphibians and other snakes. Mammals, lizards and birds are also eaten on a rare occasion. Some evidence exist to show that they are immune to toad toxins and as such they can eat them without harm.
They are not considered to be venomous but do have a gland above the upper jaw in a similar location to the venom gland of other snakes. This can produce a toxic secretion that may help to subdue prey.
Wild 2 years
Captive 6-10 years
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North America is the native home of the common garter snake. They are one of the most widespread snakes on the continent and can be found in Mexico, the United States of America and Canda. Here they live in most areas except for the arid south western states of the USA. They are only found in small parts of Mexico.
Common garter snakes can be found in aquatic, wetland and upland areas. Most of their habitats are near water courses such as ponds, lakes and streams.
When at rest they retreat to an underground burrow or under surface cover.
Mating takes place in spring at the conclusion of their hibernation period. Males emerge first and begin to seek out a female. Once she emerges the males give off pheromones to try and attract a female. Often males will outnumber the females by a large amount.
The female will select a mate and then copulation can take place. Males will mate with multiple partners in a breeding season.
Following a successful mating the female will return to her summer habitat and begin to feed. The young incubate inside the female for 2-3 months.
Females give birth to between 10 and 70 live young. The variability in litter size owes to the variability in size of the females with larger females producing larger litters.
Immediately after birth the young are independent and receive no further parental care and must provide for themselves. They may remain with the mother for a couple of days after birth though.
Males mature at 1.5 years old with females maturing slightly later at 2 years old. Their growth will continue throughout the life of the snake.
Common garter snakes are active during the day. As a cold blooded animal they must generate their own heat from the environment which they do by basking in the sun.
From October to April they will undertake a hibernation where they gather in underground burrows or under rock piles and stumps where they rest through the coldest parts of the year. On mild days groups may emerge to bask.
During most of the year the common garter snake is solitary. In cold weather groups will gather to bask and this allows them to limit the loss of body heat. They will also hibernate together for the same purpose.
Predators and Threats
Common garter snakes face predation from birds of prey, mammals, other snakes, fish and turtles. The stripes down their body provide camouflage and help them to avoid predators.
When grabbed by predators the common garter snake excretes a foul substance to make them unappealing to that animal.
Humans pose no major threat to the common garter snake.
There are 13 recognized subspecies of the common garter snake which show slight variations in appearance.
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Burnie, D., 2011. Animal. 3rd ed. London: DK
Ambrose, J., 2015. Wildlife Of The World. 1st ed. London: Dorling Kindersley.
Zimmerman, R. 2013. "Thamnophis sirtalis" (On-line), Animal Diversity Web. Accessed July 29, 2020 at http://www.biokids.umich.edu/accounts/Thamnophis_sirtalis/
Vtfishandwildlife.com. 2020. Common Garter Snake | Vermont Fish & Wildlife Department. [online] Available at: <https://vtfishandwildlife.com/learn-more/vermont-critters/reptiles/common-garter-snake> [Accessed 30 July 2020].
Cwf-fcf.org. 2020. Common Garter Snake. [online] Available at: <https://cwf-fcf.org/en/resources/encyclopedias/fauna/amphibians-and-reptiles/common-garter-snake.html> [Accessed 30 July 2020].
Frost, D.R., Hammerson, G.A. & Santos-Barrera, G. 2015. Thamnophis sirtalis. The IUCN Red List of Threatened Species 2015: e.T62240A68308267. https://dx.doi.org/10.2305/IUCN.UK.2015-2.RLTS.T62240A68308267.en. Downloaded on 29 July 2020.
Canadian Geographic. 2020. Animal Facts: Common Garter Snake. [online] Available at: <https://www.canadiangeographic.ca/article/animal-facts-common-garter-snake> [Accessed 30 July 2020].
Burke Museum. 2020. Common Garternsake. [online] Available at: <https://www.burkemuseum.org/collections-and-research/biology/herpetology/amphibians-reptiles-washington/common-garternsake> [Accessed 30 July 2020].
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