Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Widely distributed across North America, found from the Atlantic to the Pacific coast, and from Subarctic regions of Canada to northern Mexico.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Non-venomous (though they possess a Duvernoy's gland that produces a mild neurotoxic secretion, they lack true fangs for delivery).
Danger Level
Harmless. They are not a threat to humans or pets; bites are rare and usually only occur if the snake is handled roughly.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Conservation
Least Concern (IUCN). They are highly adaptable and abundant, though they face threats from habitat loss and pesticide use affecting their prey.
Physical Description
Highly variable. This specimen shows a dark ground color with three distinct light longitudinal stripes (dorsal and lateral). The pattern between stripes often features a checkered or spotted appearance. Scales are keeled, and the head is slightly wider than the neck with large eyes and round pupils.
Size & Dimensions
The specimen in the image appears to be an adult, approximately 18–26 inches long. The species typically ranges from 18 to 35 inches (46–89 cm), with a record length near 54 inches.
Habitat
Extremely versatile; found in meadows, marshes, woodlands, hillsides, and suburban gardens. They prefer areas near water sources but can thrive in various terrestrial environments up to high elevations.
Behavior & Temperament
Diurnal and active forager. Generally docile but will flatten its head and body to appear larger, strike defensively, or release a foul-smelling musk and cloacal contents if captured.
Diet & Feeding
Generalist carnivore. Feeds on earthworms, amphibians (frogs, toads, salamanders), fish, and occasionally small rodents or birds. They use active foraging and swallow prey alive.
Reproduction
Viviparous (gives birth to live young). Mating occurs in early spring often in 'mating balls.' Litter sizes range from 3 to 80 young, typically born between July and October.
Venom Profile
Non-venomous - no medically significant venom. Secretions may cause mild swelling or itching in rare allergic individuals.
Look-alikes
Ribbon Snakes (Thamnophis saurita) which are more slender with stripes on different scale rows; Water Snakes (Nerodia spp.) which are heavier-bodied and lack the distinct stripes.
Conservation Status
Least Concern (IUCN). They are highly adaptable and abundant, though they face threats from habitat loss and pesticide use affecting their prey.
Cultural Significance
One of the most commonly encountered snakes in North America, often serving as a 'gateway' species for budding naturalists. They play a vital ecological role in controlling pest and amphibian populations.
Notable Features
Highly cold-tolerant, they are often the first snakes to emerge in spring. Some populations are famous for their resistance to tetrodotoxin found in the Pacific newts they consume.