Common Garter Snake
Thamnophis sirtalis • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Widely distributed across North America, ranging from the Atlantic Coast to the Pacific Coast, and from Subarctic regions of Canada to the southernmost parts of the United States and Northern Mexico.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Non-venomous (Technically possesses mild neurotoxic saliva, but lacks a delivery system significant to humans; often considered non-venomous in a medical context).
Danger Level
Harmless. They are not dangerous to humans or pets. Bites may cause minor localized irritation or swelling but do not require complex medical treatment.
Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: Thamnophis sirtalis
Conservation
IUCN Status: Least Concern. They are highly adaptable and common throughout their range, though local populations can be affected by habitat loss and pollution.
Physical Description
Appears as a slender snake with a dark background color (black or dark brown) and three distinctive longitudinal stripes: one central dorsal stripe and two lateral stripes. The pattern often includes a checkered effect between the stripes. Head is slightly wider than the neck with large eyes and round pupils. Scales are keeled.
Size & Dimensions
The specimen in the image appears to be a juvenile or sub-adult, approximately 12-18 inches. Adults typically range from 18 to 26 inches, with maximum recorded lengths reaching nearly 4 feet.
Habitat
Extremely versatile; found in meadows, marshes, woodlands, and hillsides. They have a strong preference for being near water sources like ponds, lakes, and streams. Often found in suburban gardens and parks.
Behavior & Temperament
Diurnal and active forager. When threatened, they may flatten their bodies to appear larger, strike defensively, or release a foul-smelling musk from their cloaca. They are generally shy and prefer to flee.
Diet & Feeding
Generalist carnivores. Diet includes earthworms, slugs, frogs, toads, salamanders, fish, and occasionally small rodents or birds. They hunt by active foraging using chemosensory tracking (tongue-flicking).
Reproduction
Ovoviviparous (giving birth to live young). Breeding occurs in spring shortly after emerging from brumation. Litters are large, typically ranging from 10 to 40 young, born in late summer.
Venom Profile
Non-venomous - no medically significant venom. Saliva contains mild toxins effective on small prey like amphibians.
Look-alikes
Often confused with Ribbon Snakes (Thamnophis saurita), which are more slender with stripes on different scale rows, or Lined Snakes (Tropidoclonion lineatum), which have a double row of half-moon spots on the belly.
Conservation Status
IUCN Status: Least Concern. They are highly adaptable and common throughout their range, though local populations can be affected by habitat loss and pollution.
Cultural Significance
One of the most commonly encountered snakes in North America, playing a vital role in controlling pest populations like slugs and insects. They are frequently used in biological research due to their abundance.
Notable Features
Highly cold-tolerant, sometimes emerging from hibernation on warm winter days. Known for forming large 'mating balls' in certain northern populations (like the Narcisse dens in Canada) where thousands congregate.