Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Widespread across North America, from the Atlantic to the Pacific coasts and as far north as subarctic Canada to as far south as Florida.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Mildly venomous (opisthoglyphous - rear-fanged), but effectively harmless to humans.
Danger Level
Harmless. They are not prone to biting unless handled roughly; even then, they cannot cause significant harm to a human.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Conservation
IUCN Least Concern. They are stable and abundant markers of healthy ecosystems, though threatened by pesticide use and habitat loss.
Physical Description
Keeled scales, three longitudinal stripes (usually yellow, white, or green) on a dark base color, though patterns vary. Head is slightly wider than the neck, eyes are large with round pupils. Visible dark labial bars on the upper scales of the mouth.
Size & Dimensions
Specimen appears to be an adult around 45-60 cm. Typical adult size range is 46 to 137 cm.
Habitat
Highly adaptable, found in forests, grasslands, and marshes, but almost always near water sources. Common in suburban gardens, parks, and agricultural land (0 to 2,500m elevation).
Behavior & Temperament
Diurnal active forager. Generally elusive, but if cornered, they may flatten their heads, strike defensively, or release a foul-smelling musk (cloacal secretions).
Diet & Feeding
Generalist carnivore eating earthworms, slugs, frogs, toads, salamanders, and small fish. Uses active foraging and sometimes swallows prey alive or uses mild toxins to immobilize.
Reproduction
Ovoviviparous (bearing live young) with litters ranging from 10 to 40 neonates, typically born in late summer or early autumn.
Venom Profile
Mild neurotoxic properties contained within saliva; causes localized swelling and itching in rare cases of prolonged bites. Non-medically significant to humans.
Look-alikes
Ribbon Snakes (Thamnophis saurita) which have longer tails and stripes on different scale rows, and Queen Snakes (Regina septemvittata).
Conservation Status
IUCN Least Concern. They are stable and abundant markers of healthy ecosystems, though threatened by pesticide use and habitat loss.
Cultural Significance
Highly beneficial for gardeners as they control populations of garden pests like slugs and grubs. Often the first snake encountered by children in North America, serving as an educational species.
Notable Features
Thamnophis sirtalis is famous for its resistance to tetrodotoxin (TTX) found in Newts, allowing them to eat prey that is lethally toxic to most other predators.