Garter snakes are common, non-venomous snakes found widely across North America, from Canada to Central America. This article details their distinctive physical characteristics for identification.
Their Overall Build
Garter snakes are typically small to medium-sized, generally ranging from 18 to 26 inches in length, though some individuals can grow up to 54 inches. They possess a slender body shape with a head that is slightly wider than their neck.
A notable feature of garter snakes is their keeled scales. These scales have a raised ridge along their length, which provides a rougher texture when touched, unlike the smooth, glossy scales found on some other snakes. Their eyes are relatively large and round, with a bright red tongue tipped in black.
Signature Stripes and Patterns
Garter snakes are most recognized by their longitudinal stripes running down their bodies. They typically have three light-colored stripes: one along the center of the back and one on each side, usually located on the second and third rows of scales above the belly. These stripes can vary in color, appearing yellow, white, green, or even blue.
The background body color of garter snakes is also variable, often appearing black, brown, gray, or olive green. In many individuals, a checkered pattern of dark spots is visible between these stripes, which can sometimes make the stripes appear less continuous.
Color and Pattern Diversity
While garter snakes share common striped patterns, their exact coloration and marking prominence can differ significantly across species and geographic locations. For instance, the common garter snake (Thamnophis sirtalis) has 13 recognized subspecies, each with potential variations. Some subspecies, like the blue-striped garter snake found in Florida, exhibit vibrant blue striping.
Other regional variations include the San Francisco garter snake, which displays black and red stripes with a bright orangey-red head. The red-sided garter snake (Thamnophis sirtalis parietalis) often features prominent red or orange bars between its stripes.
Telling Them Apart From Other Snakes
Distinguishing garter snakes from other snake species involves observing several key features. Ribbon snakes (Thamnophis saurita), though closely related and also striped, are generally more slender with longer tails, often accounting for one-third or more of their total body length, compared to a garter snake’s tail, which is typically one-quarter or less. Ribbon snakes also tend to have more distinct stripes without the checkered patterns often seen on garter snakes, and they lack the dark vertical bars on their lip scales that garter snakes often have.
Non-venomous water snakes (genus Nerodia) are often confused with garter snakes but typically have thicker bodies and lack the distinct longitudinal stripes. While garter snakes produce a mild venom and can release a foul-smelling musk if threatened, they are generally harmless to humans. The presence of prominent stripes is usually a clear indicator of a garter snake, differentiating them from many other snake types.