Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. sirtalis
Widely distributed throughout North America, ranging from Nova Scotia and southern Canada down through the United States to the Gulf of Mexico and Florida, excluding parts of the arid southwest.
Look up Common Garter Snake in the Snake Encyclopedia →Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. sirtalis
Conservation
IUCN Red List status is Least Concern, with stable populations across most of its native range, though local populations face threats from habitat loss, road mortality, and intentional killing.
Physical Description
Slender body featuring a dark base coloration with three prominent longitudinal light-colored stripes (one vertebral and two lateral), a dark-patterned head, and keeled scales giving a textured appearance.
Size & Dimensions
Specimen is estimated around 45-60 cm in length. Typical adult size ranges from 46 to 137 cm (18 to 54 inches) total length.
Habitat
Found in a diverse array of habitats including forests, fields, grasslands, marshes, ponds, and suburban areas, typically near permanent or temporary water sources.
Diet & Feeding
Diet consists primarily of amphibians (frogs, toads, salamanders), earthworms, small fish, and occasionally small mammals or birds; utilizes an active foraging strategy.
Reproduction
Viviparous (gives live birth), producing litters typically ranging from 10 to 40+ young in mid-to-late summer, often participating in large communal hibernation aggregations.
Look-alikes
Frequently confused with other garter snake species (such as the Ribbon Snake, Thamnophis saurita) and lined snakes (Tropidoclonion lineatum); distinguished by specific scale counts, stripe placement, and head markings.
Conservation Status
IUCN Red List status is Least Concern, with stable populations across most of its native range, though local populations face threats from habitat loss, road mortality, and intentional killing.
Cultural Significance
Commonly encountered in suburban yards and parks, making it one of the most frequently observed snakes by humans in North America. Plays a vital role in controlling amphibian and invertebrate populations.
Notable Features
Exhibits great color polymorphism across its vast geographic range, ranging from bright red and green variants to stark black melanistic morphs.