Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. sirtalis
Widely distributed across North America, ranging from southern Canada through the United States down to parts of northeastern Mexico, inhabiting diverse biomes from subtropical wetlands to subarctic forests.
Look up Common Garter Snake in the Snake Encyclopedia →Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. sirtalis
Conservation
Least Concern according to the IUCN Red List, with widespread populations, though local populations face threats from habitat fragmentation, road mortality, and intentional persecution.
Physical Description
Dark olive-brown to black dorsal background featuring three prominent longitudinal yellowish stripes (one down the vertebral line and two on the lateral scales), a light-colored chin and throat, round pupils, keeled dorsal scales giving a textured appearance, and a moderately stout body.
Size & Dimensions
The pictured adult specimen appears to be approximately 30 to 36 inches in length. Typical adults range from 18 to 54 inches (46 to 137 cm) in total length, with females generally growing larger than males.
Habitat
Highly adaptable, found in fields, woodlands, marshes, prairies, and suburban backyards, typically near permanent or temporary water sources such as ponds, lakes, streams, and ditches, from sea level up to elevations over 8,000 feet.
Diet & Feeding
Generalist carnivore feeding on amphibians, earthworms, small fish, rodents, and nestling birds, utilizing an active foraging strategy to locate prey by scent and capturing it directly with the jaws.
Reproduction
Viviparous (giving birth to live young), producing litters typically ranging from 10 to 40 offspring, though exceptionally large females can birth upwards of 80. Mating occurs primarily in the spring immediately following emergence from brumation.
Look-alikes
Frequently confused with other striped species within the genus Thamnophis, such as the Ribbon Snake (Thamnophis sauritus) which is slenderer with lateral stripes positioned higher on the scale rows, or various species of lined snakes and grass snakes.
Conservation Status
Least Concern according to the IUCN Red List, with widespread populations, though local populations face threats from habitat fragmentation, road mortality, and intentional persecution.
Cultural Significance
Frequently featured in North American environmental education programs due to its docile nature and common occurrence in suburban areas, while also playing an essential ecological role in controlling amphibian and invertebrate populations.
Notable Features
Exhibits communal overwintering (brumation) behaviors where hundreds of individuals congregate in underground dens, and males often emerge first and exhibit pheromone mimicry to confuse rival males during the breeding season.