Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. sirtalis
North America, ranging widely across the United States, Canada, and parts of Mexico, inhabiting diverse biomes from subarctic regions to subtropical wetlands.
Look up Common Garter Snake in the Snake Encyclopedia →Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. sirtalis
Conservation
Listed as Least Concern on the IUCN Red List, with stable populations across most of its native range, though local populations face threats from habitat fragmentation, road mortality, and intentional killing.
Physical Description
The specimen exhibits dark, nearly uniform blackish or very dark gray dorsal coloration, contrasting sharply with a pale, whitish or cream-colored venter. The body is slender and moderately elongated with distinctly keeled scales, giving a matte appearance.
Size & Dimensions
Estimated specimen length is approximately 60 to 75 cm. The typical adult size range for the species is 46 to 130 cm, with females generally growing larger than males.
Habitat
Found in a broad range of habitats including fields, woodlands, marshes, drainage ditches, and suburban lawns, typically near permanent or temporary water sources with access to cover.
Diet & Feeding
Diet consists primarily of amphibians, earthworms, small fish, and occasionally small rodents or other reptiles, captured through active foraging and seized with the jaws.
Reproduction
Viviparous, giving birth to live young rather than laying eggs. Mating typically occurs in spring shortly after emerging from hibernation, resulting in litters ranging from 10 to as many as 40 or more offspring.
Look-alikes
Frequently confused with other natricine snakes such as ribbon snakes (Thamnophis saurita) and water snakes (Nerodia spp.), distinguished primarily by specific dorsal and lateral stripe configurations and scale counts.
Conservation Status
Listed as Least Concern on the IUCN Red List, with stable populations across most of its native range, though local populations face threats from habitat fragmentation, road mortality, and intentional killing.
Cultural Significance
An ecologically significant species that helps control populations of amphibians and invertebrates, frequently serving as an educational animal in schools and nature centers due to its adaptability and gentle demeanor.
Notable Features
Known for high adaptability to human-altered environments, communal overwintering habits in large hibernacula, and a complex pheromone system where males sometimes mimic female scents to emerge from hibernation early.