Common Garter Snake
Thamnophis sirtalis • Order: Squamata; Suborder: Serpentes; Family: Colubridae; Subfamily: Natricinae; Genus: Thamnophis; Species: sirtalis
Extensively distributed throughout North America, ranging from the subarctic regions of Canada to the Southern United States and Northern Mexico. In Indiana, they are found in all 92 counties.
Look up Common Garter Snake in the Snake Encyclopedia →Venomous Status
Harmless / Mildly venomous (contains mild neurotoxic saliva, but lacks a sophisticated delivery system; no traditional fangs)
Danger Level
Harmless. While they may bite if handled, it is of no medical significance to humans beyond potential minor irritation or infection risk.
Family
Order: Squamata; Suborder: Serpentes; Family: Colubridae; Subfamily: Natricinae; Genus: Thamnophis; Species: sirtalis
Conservation
IUCN Status: Least Concern. They are resilient to human-altered landscapes but face threats from habitat loss and pollution (pesticides).
Physical Description
Highly variable; this specimen shows a dark dorsal color with a distinct light-colored dorsal stripe and a checkered pattern of black spots. Round pupils and keeled scales are present.
Size & Dimensions
Typical adult length is 18 to 26 inches (46-66 cm). This specimen appears to be an average-sized adult. Maximum recorded length is roughly 4 feet (122 cm).
Habitat
Highly adaptable generalist found in meadows, marshes, woodlands, and suburban gardens. They prefer areas near water but are found in diverse microhabitats from sea level to high elevations.
Behavior & Temperament
Diurnal and active during the day. Generally shy; when threatened, they may flatten their bodies to appear larger, release a foul-smelling musk/cloacal discharge, or strike as a last resort.
Diet & Feeding
Generalist carnivore eating earthworms, slugs, frogs, toads, salamanders, and occasionally small fish or rodents. They are active foragers that swallow prey alive without constriction.
Reproduction
Ovoviviparous (gives birth to live young). Litters typically range from 10 to 40 young, born between mid-summer and early autumn.
Venom Profile
Mildly neurotoxic saliva used primarily for immobilizing small prey; non-dangerous to humans.
Look-alikes
Commonly confused with Ribbonsnakes (Thamnophis saurita) and Plains Garter Snakes (Thamnophis radix). Distinguishable by the placement of the lateral stripes on specific scale rows.
Conservation Status
IUCN Status: Least Concern. They are resilient to human-altered landscapes but face threats from habitat loss and pollution (pesticides).
Cultural Significance
One of the most commonly encountered snakes in North America, playing a vital ecological role in controlling pest populations like slugs and insects in suburban gardens.
Notable Features
Remarkable for their cold tolerance, often being the first snakes to emerge in spring. Some populations have evolved resistance to the potent tetrodotoxin (TTX) found in Newts.
Notes
Indiana afternoon