Common Garter Snake
Thamnophis sirtalis • Order: Squamata; Suborder: Serpentes; Family: Colubridae; Subfamily: Natricinae; Genus: Thamnophis; Species: Thamnophis sirtalis
Widely distributed across North America, from the Atlantic Coast to the Pacific Coast, and from subarctic regions of Canada south through most of the United States to northern Mexico.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Non-venomous (though biologically possessing mild neurotoxic saliva, it lacks a delivery system significant to humans).
Danger Level
Harmless; they pose no threat to humans or pets. Bites are rare and usually only occur if the snake is handled roughly.
Family
Order: Squamata; Suborder: Serpentes; Family: Colubridae; Subfamily: Natricinae; Genus: Thamnophis; Species: Thamnophis sirtalis
Conservation
IUCN Red List: Least Concern. Generally abundant, though locally threatened by habitat loss, pesticide use, and road mortality.
Physical Description
Greenish-brown to black ground color with three distinct longitudinal yellow or cream stripes (one dorsal, two lateral). A checkered pattern of black spots is visible between stripes. The head is slightly wider than the neck, eyes are large with round pupils, and scales are heavily keeled.
Size & Dimensions
This specimen appears to be an adult approximately 18-24 inches (45-60 cm) long. The species typically ranges from 18 to 26 inches, with a record maximum of roughly 49 inches.
Habitat
Extremely versatile, found in forests, fields, prairies, and suburban gardens. They prefer areas near water sources like ponds, lakes, streams, and marshes. They range from sea level up to high mountain elevations.
Behavior & Temperament
Diurnal and active forager. Generally shy and will flee if approached. If cornered, they may flatten their heads, strike, or release a foul-smelling musk from their cloaca. They are cold-tolerant and emerge early in spring.
Diet & Feeding
Generalist carnivores that eat earthworms, amphibians (frogs, toads, salamanders), fish, and occasionally small rodents or birds. They use active foraging and swallow prey alive without constriction.
Reproduction
Ovoviviparous (gives birth to live young). Mating occurs in early spring, often in large communal dens called hibernacula. Females produce 10 to 40 young per litter in late summer.
Venom Profile
Non-venomous - no medically significant venom. Saliva may cause mild localized swelling or itching in sensitive individuals.
Look-alikes
Ribbon Snakes (Thamnophis saurita) which are more slender with stripes on scale rows 3 and 4 (vs. 2 and 3 in sirtalis), and various species of DeKay's Brownsnakes (Storeria dekayi) which lack the prominent stripes.
Conservation Status
IUCN Red List: Least Concern. Generally abundant, though locally threatened by habitat loss, pesticide use, and road mortality.
Cultural Significance
Often the first snake encountered by children and gardeners. They are ecologically beneficial as pest control for garden slugs and insects. In some cultures, they are seen as symbols of spring.
Notable Features
Remarkable for their resistance to tetrodotoxin (TTX) found in Newts (Taricha species), allowing them to consume toxic prey that would kill other predators. They are also known for forming massive 'mating balls' after emerging from hibernation.