Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: sirtalis
Extensively distributed throughout North America, ranging from the subarctic regions of Canada through the United States to the southernmost parts of the Gulf Coast and parts of Mexico.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Harmless to humans; technically mildly venomous (opisthoglyphous) towards small prey via Duvernoy's gland.
Danger Level
Harmless. They are not aggressive and their bite, while potentially causing localized redness or itching, lacks medical significance for humans.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: sirtalis
Conservation
Least Concern (IUCN). Extremely common and resilient, though local populations can be affected by habitat loss and pesticide use.
Physical Description
Characterized by three longitudinal yellow to cream-colored stripes (one dorsal, two lateral) on a dark green to blackish background. They have keeled scales and a relatively large head distinct from the neck. A 'checkered' pattern of dark spots may be visible between the stripes.
Size & Dimensions
Specimen appears to be an adult approximately 24-30 inches (60-76 cm) in length. Typical species range is 18 to 54 inches (46 to 137 cm).
Habitat
Highly adaptable to diverse habitats including woodlands, grasslands, meadows, and marshes. They are often found near water sources and are common in suburban backyards and gardens.
Behavior & Temperament
Primarily diurnal. Generally shy and will attempt to flee; if cornered, they may flatten their heads, strike, or release a foul-smelling musk from their cloaca.
Diet & Feeding
Generalist predators; primarily consume earthworms, slugs, frogs, toads, salamanders, and occasionally small fish or rodents. They use active foraging to locate prey.
Reproduction
Viviparous (gives birth to live young). Breeding occurs in spring after emergence from brumation. Litters typically range from 10 to 40 neonates.
Venom Profile
Non-medically significant. Possesses a mild neurotoxin that facilitates the immobilization of small amphibians and fish; harmless to humans and pets.
Look-alikes
Commonly confused with Ribbon Snakes (Thamnophis saurita) which are more slender with higher lateral stripes, and Lined Snakes (Tropidoclonion lineatum).
Conservation Status
Least Concern (IUCN). Extremely common and resilient, though local populations can be affected by habitat loss and pesticide use.
Cultural Significance
One of the most recognizable snakes in North America. They play a crucial role in controlling populations of garden pests and serve as a common introductory species for young naturalists.
Notable Features
One of the few snake species that can safely consume toxic amphibians like newts and toads due to a developed resistance to tetrodotoxin.