Common Garter Snake
Thamnophis sirtalis • Order: Squamata; Suborder: Serpentes; Family: Colubridae; Subfamily: Natricinae; Genus: Thamnophis; Species: Thamnophis sirtalis
Widespread throughout North America, ranging from the Atlantic to the Pacific coast, and from subarctic regions in Canada to the southernmost tip of Florida. They are among the most northerly distributed snakes in the world.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Harmless / Non-venomous (though biologically possess a mild neurotoxic saliva that is not dangerous to humans).
Danger Level
Harmless. The species is not aggressive and lacks medically significant venom. Secondary infections from bites are the only minor concern.
Family
Order: Squamata; Suborder: Serpentes; Family: Colubridae; Subfamily: Natricinae; Genus: Thamnophis; Species: Thamnophis sirtalis
Conservation
IUCN status: Least Concern. They are resilient to human-altered landscapes, though local populations are threatened by habitat loss and pesticide use.
Physical Description
Characterized by three longitudinal yellow or cream-colored stripes on a dark green, brown, or black background. One stripe runs down the center of the back, and one on each side. The head is slightly wider than the neck, eyes have round pupils, and scales are keeled (ridged).
Size & Dimensions
Specimen appears to be an adult of approximately 18-24 inches. Typical species range is 18 to 54 inches (46-137 cm), with females being significantly larger than males.
Habitat
Highly adaptable; found in meadows, marshes, woodlands, andhillsides. They prefer moist environments and are frequently found near water sources like ponds, streams, and lakes, as well as in suburban backyards and gardens.
Behavior & Temperament
Diurnal and active during the day. Generally shy and will flee when approached. If cornered, they may flatten their heads, strike, or release a foul-smelling musk and cloacal discharge as a defense.
Diet & Feeding
Active forager with a varied diet including earthworms, slugs, frogs, toads, salamanders, and occasionally small fish or rodents. They swallow their prey whole and alive.
Reproduction
Ovoviviparous (gave birth to live young). Breeding occurs in spring shortly after emerging from hibernation. Litters can range from 10 to 40 young, although larger litters have been recorded.
Venom Profile
Non-venomous - no medically significant venom. They lack a delivery system for significant amounts of toxins; saliva may cause mild itching or swelling in sensitive individuals.
Look-alikes
Commonly confused with Ribbon Snakes (Thamnophis saurita), which are thinner with longer tails, and Plains Garter Snakes (Thamnophis radix), which have stripes on different scale rows.
Conservation Status
IUCN status: Least Concern. They are resilient to human-altered landscapes, though local populations are threatened by habitat loss and pesticide use.
Cultural Significance
Often the first snake encountered by children; they play a vital role in ecosystem pest control by consuming garden pests like slugs and insects. They are culturally recognized as 'garden snakes'.
Notable Features
One of the few snake species capable of tolerating cold temperatures; some populations hibernate communally in 'hibernacula' containing thousands of individuals.