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 subarctic regions of Canada to the Rio Grande in Texas and from the Atlantic to the Pacific coasts.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Harmless to humans; technically possesses a mild neurotoxic venom produced by the Duvernoy's gland, but lacks an effective delivery system (aglyphous).
Danger Level
Harmless. Bites may cause minor localized irritation or swelling but do not require medical intervention for the venom itself.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Conservation
IUCN Red List: Least Concern. Highly adaptable and abundant throughout most of its range.
Physical Description
Small to medium snake with three longitudinal stripes (one dorsal, two lateral) which can be yellow, white, or green. The background color is dark green to black with a checkered pattern of dark spots. Scales are keeled; head is slightly wider than the neck; eyes have round pupils.
Size & Dimensions
The specimen appears to be an adult approximately 50-70 cm in length. Typical adult size for the species ranges from 46 to 137 cm.
Habitat
Extremely versatile, found in meadows, marshes, woodlands, and suburban gardens. They prefer areas near water sources and are found from sea level to high alpine meadows.
Behavior & Temperament
Diurnal and active forager. When threatened, they may flatten their heads, strike defensively, or discharge a foul-smelling musk from the cloaca. Generally flighty rather than aggressive.
Diet & Feeding
Highly varied diet including earthworms, amphibians (frogs, toads, salamanders), fish, and occasionally small rodents or birds. They are active hunters that swallow prey alive.
Reproduction
Ovoviviparous (gives birth to live young). Mating occurs in spring shortly after emerging from hibernation; females give birth to 10-40 young in late summer.
Venom Profile
Mildly neurotoxic to small prey; generally considered non-venomous and not medically significant to humans.
Look-alikes
Ribbon Snakes (Thamnophis saurita) which are more slender with stripes on different scale rows; Water Snakes (Nerodia spp.) which are heavier-bodied and lack the distinct dorsal stripe.
Conservation Status
IUCN Red List: Least Concern. Highly adaptable and abundant throughout most of its range.
Cultural Significance
One of the most commonly encountered snakes in North America, playing a vital role in controlling pest populations and as a key species in backyard ecosystems.
Notable Features
One of the most cold-tolerant snake species in the world, capable of surviving in the far north of Canada where other reptiles cannot exist. They are known to hibernate in large communal dens called hibernacula.