The term “garden snake” commonly refers to the Common Garter Snake, scientifically known as Thamnophis sirtalis. This species is the most widespread and recognizable snake across North America, often encountered in yards and gardens, which gives it its familiar name. Learning to identify its specific characteristics is the first step in understanding this highly adaptable reptile. This article focuses on the distinct physical features, coloration, behavior, and structural details of the Common Garter Snake.
Defining Physical Dimensions and Structure
The Common Garter Snake is characterized by a slender body build that contributes to its agility. Most adults measure between 18 and 26 inches in total length, though larger individuals can occasionally reach up to 52 inches. Females typically grow longer and possess a heavier build than the males.
The head is slightly wider than the neck. A defining structural feature is the texture of the scales, which are keeled, meaning each scale has a raised ridge running lengthwise down its center. This keeling gives the snake a rough, rather than glossy, appearance. The eyes are relatively large, and the pupils are round.
Signature Stripes and Coloration
The most distinctive feature of the Common Garter Snake is its striped pattern. The snake typically displays three light-colored longitudinal stripes running the entire length of its body: one down the center of the back (the dorsal stripe) and two along the sides (the lateral stripes).
The background color can be highly variable, often appearing black, dark brown, or olive green. The stripes themselves can range in color from yellow, white, or greenish to blue. The spaces between these stripes frequently exhibit a checkerboard pattern of dark spots or blotches. This overall coloration is subject to significant geographical variation, with some subspecies exhibiting red stripes or a nearly all-black (melanistic) appearance.
Habitat and Behavior Clues for Identification
Contextual clues, such as where and when the snake is seen, aid in identification. Common Garter Snakes are highly adaptable and thrive in diverse environments, from woodlands and meadows to suburban lawns and gardens. They frequently seek out moist, grassy areas and are often found near water sources like ponds, streams, or ditches.
The snake is primarily diurnal, meaning it is most active during the day. They are often observed basking in sunny spots to regulate their body temperature. Their diet consists largely of earthworms, amphibians like frogs and salamanders, and fish. When disturbed, they may quickly move away or release a foul-smelling musk from their anal glands as a defense mechanism.
Differentiation from Look-Alikes
Distinguishing the Common Garter Snake from similar-looking species is important for accurate identification. A common look-alike is the Ribbon Snake (Thamnophis sauritus), a close relative that is typically more slender and has a disproportionately longer tail than the Garter Snake. Ribbon Snakes also generally have a more glossy scale texture compared to the Garter Snake’s keeled scales.
It is important to remember that the Common Garter Snake is considered harmless to humans, lacking the triangular head shape and elliptical pupils characteristic of most North American pit vipers. While Garter Snakes do possess a mild venom in their saliva used to subdue small prey, they are not a danger to people.