Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: sirtalis
Widely distributed across North America, from the Atlantic coast to the Pacific, and from subarctic regions of Canada to the southern United States and northern Mexico.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Non-venomous (though possesses mildly toxic saliva produced in the Duvernoy's gland with no specialized delivery system).
Danger Level
Harmless - poses no significant threat to humans or pets. Bites may cause minor local irritation but are not dangerous.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: sirtalis
Conservation
Least Concern (IUCN). Extremely resilient and adaptable, though localized populations face threats from habitat loss and pollution.
Physical Description
Dark background color (black, brown, or olive) with three distinct longitudinal stripes (typically yellow, white, or green). Distinctive checkered pattern of black spots between stripes. Scales are heavily keeled, giving a textured appearance.
Size & Dimensions
Specimen appears to be an adult; typical species length ranges from 46 to 137 cm (18 to 54 inches) with females being larger than males.
Habitat
Generalist species found in meadows, marshes, woodlands, and suburban gardens. Predominantly found near water sources; elevation range from sea level to over 2,500 meters.
Behavior & Temperament
Diurnal and active forager. Generally shy and quick to flee. If cornered, it may flatten its head, strike defensively, or discharge a foul-smelling musk from the cloaca.
Diet & Feeding
Carnivorous generalist. Consumes earthworms, amphibians (frogs, toads, salamanders), fish, and occasionally small rodents. Hunts by active foraging and swallows prey alive.
Reproduction
Ovoviviparous (gives birth to live young). Litters typically range from 10 to 40 young, though up to 80 have been recorded. Mating usually occurs in early spring following emergence from brumation.
Venom Profile
Non-venomous - no medically significant venom for humans; saliva contains mild neurotoxins to immobilize small prey.
Look-alikes
Ribbon Snakes (Thamnophis saurita) which are leaner with longer tails and lack markings on the labial scales; DeKay's Brownsnake (Storeria dekayi) which lacks the bright yellow stripes.
Conservation Status
Least Concern (IUCN). Extremely resilient and adaptable, though localized populations face threats from habitat loss and pollution.
Cultural Significance
One of the most commonly encountered snakes in North America. Highly valued by gardeners for controlling pests like slugs and insects; frequently used in biological research regarding pheromones and brumation.
Notable Features
Highly cold-tolerant; can remain active at lower temperatures than most other snakes. Known for forming large communal 'mating balls' when emerging from winter dens.