Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Widely distributed throughout North America, ranging from the subarctic regions of Canada through most of the continental United States and into parts of northern Mexico.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Mildly venomous (opisthoglyphous saliva); however, it is functionally non-venomous to humans.
Danger Level
Harmless; while they may bite if handled aggressively, the bite causes only minor localized irritation or swelling and no significant medical risk.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Conservation
IUCN Red List: Least Concern. It is one of the most common and adaptable snake species in its range.
Physical Description
Slender body with three longitudinal stripes (one dorsal, two lateral) ranging from yellow to cream-colored. Between the stripes is a dark checkerboard pattern of blackish or brownish blotches. The head is slightly wider than the neck, eyes have round pupils, and scales are keeled.
Size & Dimensions
The specimen in the image appears to be an adult, approximately 45-60 cm (18-24 inches) long. Typical species range is 46-137 cm (18-54 inches).
Habitat
Extremely versatile; found in forests, grasslands, meadows, and wetlands. It is often found near water sources but is frequently seen in suburban gardens and backyard habitats at various elevations.
Behavior & Temperament
Diurnal and active. Generally shy and will flee if approached. If cornered, it may flatten its head, strike defensively, or release a foul-smelling musk from its cloaca.
Diet & Feeding
Active forager with a broad diet including earthworms, slugs, frogs, toads, salamanders, and occasionally small fish or rodents. They swallow prey whole without constriction.
Reproduction
Viviparous (gives birth to live young). Litters typically range from 10 to 40 neonates, born in late summer or early autumn.
Venom Profile
The saliva contains mild neurotoxins designed to immobilize small prey like amphibians; it lacks a delivery system capable of harming humans.
Look-alikes
Often confused with Ribbon Snakes (Thamnophis saurita), which are more slender and have the lateral stripe on scale rows 3 and 4, whereas Garter Snakes have them on rows 2 and 3. Also resembles the Brown Snake (Storeria dekayi).
Conservation Status
IUCN Red List: Least Concern. It is one of the most common and adaptable snake species in its range.
Cultural Significance
Commonly encountered by humans, it is a staple of suburban ecology and serves as an important bio-indicator and pest-control predator of garden slugs.
Notable Features
Highly cold-tolerant; some populations are known to hibernate in massive communal dens containing thousands of individuals, most notably in Manitoba, Canada.