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 to the Pacific, and from the subarctic regions of Canada to the Rio Grande in the south.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Harmless to humans; technically mildly venomous (lacks specialized fangs but possesses a Duvernoy's gland).
Danger Level
Harmless; they generally flee when approached and pose no significant threat to humans or pets.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Conservation
IUCN Least Concern; stable population although some subspecies may face localized threats from habitat loss.
Physical Description
Features three light-colored longitudinal stripes (yellow or greenish) on a dark background; head is slightly wider than the neck, eyes have round pupils, and dorsal scales are keeled.
Size & Dimensions
Specimen appears to be an adult around 20-30 inches; species typically ranges from 18-54 inches in total length.
Habitat
Generalist species found in meadows, marshes, woodlands, and suburban gardens; typically resides near water sources with abundant vegetation and low-lying microhabitats.
Behavior & Temperament
Diurnal and active; when threatened, they may discharge a foul-smelling musk or strike defensively, though they often prefer to escape.
Diet & Feeding
Active forager consuming earthworms, amphibians (frogs, toads), slugs, and occasionally small fish or rodents.
Reproduction
Ovoviviparous; females give birth to live young during late summer or early autumn with litter sizes ranging from 10 to 40 individuals.
Venom Profile
Mildly neurotoxic saliva primarily effective on amphibians and small prey; non-medically significant to humans.
Look-alikes
Ribbon snakes (Thamnophis saurita) which are more slender with stripes on higher scale rows, and various species of garter snakes which vary by regional coloration.
Conservation Status
IUCN Least Concern; stable population although some subspecies may face localized threats from habitat loss.
Cultural Significance
Commonly encountered in residential areas; plays a vital role in ecosystem pest control by consuming garden pests like slugs and insects.
Notable Features
Remarkable cold tolerance allowing them to be among the first snakes active in spring; some populations are famous for mass communal denning during hibernation.