Common Gartersnake

Adventure step • Meet the species

Overview

The common gartersnake (Thamnophis sirtalis) is one of North America's most widespread and abundant snakes. Its range extends from the cold forests of Canada in the north to the warmer climates of Mexico in the south, and from the Atlantic coast to the Pacific Ocean. This adaptable serpent has successfully colonized an astonishing variety of habitats thanks to its ability to survive in both cold and warm climates. The name 'garter' comes from the snake's characteristic stripes, which resembled the striped garters that were popular in the 18th century for holding up stockings. The common gartersnake is a relatively small snake that typically reaches lengths between 46 and 66 centimeters, though some specimens can grow up to 137 centimeters long. It has three distinctive yellow or white stripes running the length of its body – one down the back and one on each side. The base color varies from black, brown, green, or olive-green, and between the stripes there is often a checkered pattern. This color variation is enormous; there are over 30 different subspecies with different color combinations. Some populations have red or orange stripes instead of yellow, while others can be almost entirely black. Unlike many other snakes, the common gartersnake is ovoviviparous, meaning it gives birth to live young instead of laying eggs. Females can give birth to between 10 and 85 offspring in a single litter, typically in July or August. The young are completely independent from birth and measure only 12-23 centimeters. The common gartersnake is an opportunistic hunter that eats a wide spectrum of prey, including earthworms, slugs, frogs, fish, salamanders, bird nestlings, and small rodents. A fascinating adaptation is that some populations have developed resistance to tetrodotoxin, the deadly poison found in rough-skinned newts. The common gartersnake is active during the day and loves to bask on rocks or near waterways. In winter, hundreds, sometimes thousands, of individuals gather in communal hibernation sites called hibernacula, often in rock crevices or old rodent burrows. When spring arrives, mass mating occurs directly outside these sites, where dozens of males may compete for a single female. The species is harmless to humans and rarely bites, but when threatened it can release a foul-smelling fluid from its anal glands. Despite its common occurrence, some local populations are threatened by habitat loss and road mortality.