**Garter Snakes** (*Thamnophis* spp.) are some of the most common and widespread snake species in North America. They are small, non-venomous (though their saliva contains a mild venom to subdue prey, they are harmless to humans), and highly beneficial to gardens and ecosystems. They are known for their striped patterns and their adaptability to diverse environments, frequently encountered in residential areas, wetlands, and near water sources. They pose no threat to people or pets.
Taxonomy and Classification
Garter Snakes belong to the family Colubridae. They are **live-bearing** (viviparous), meaning they give birth to several live young rather than laying eggs. There are numerous species and subspecies, including the Common Garter Snake (*T. sirtalis*) and the Western Terrestrial Garter Snake (*T. elegans*). They are integral parts of the food web as both predators and prey.
Physical Description
Garter Snakes are slender, small to medium-sized snakes, generally $1.5$ to $3$ feet long.
- **Coloration:** Highly variable, but characterized by **three longitudinal stripes** running down the length of the body—typically one lighter colored stripe down the back (dorsal) and one on each side. The background color is usually black, brown, or olive.
- **Defense:** When threatened or handled, they commonly emit a strong, musky-smelling secretion from glands near the base of the tail to deter predators.
- **Tongue:** They use their black, forked tongue to “smell” their environment.
Distribution and Habitat
Garter Snakes have the widest distribution of any snake genus in North America, ranging from coast to coast and from Canada to Central America. Their preferred habitat is areas near water, such as pond edges, marshes, streams, and wet meadows. However, they are also highly adapted to urban and suburban gardens, lawns, and vacant lots, especially where cover (rocks, logs, debris) is abundant.
Behavior and Conflict
Garter Snakes are active during the day (diurnal) and are often seen basking in the sun to regulate their body temperature. They are active hunters:
- **Diet:** They feed primarily on earthworms, slugs, snails, amphibians (frogs and tadpoles), small fish, and sometimes rodents. They are **highly beneficial** to gardeners due to their consumption of slugs and insect pests.
- **Overwintering:** They hibernate in groups (**hibernacula**) in rock piles, burrows, or under foundations, often using the same site year after year.
- **Conflict:** Garter Snakes are shy and harmless. Their only conflict with humans is the fear they cause due to their resemblance to venomous species, though their bite, if they do attempt one, is non-toxic.
Management and Conservation
Management is focused on conservation and exclusion, not eradication.
- **Conservation:** Their presence in a yard or garden is a sign of a healthy ecosystem and should be encouraged due to their predatory role against pests.
- **Exclusion:** If entry into a specific area (like a deck or basement) is an issue, seal all gaps and holes in the foundation. Snake fencing (a tight, solid barrier) can be installed around outdoor areas.
- **Habitat Modification:** Remove potential hiding and basking spots immediately next to the house, such as low-lying shrubs, rock piles, or debris, to discourage close proximity.
- **Removal:** If a snake is found indoors, it should be gently caught (using gloves) and released into a nearby natural area.
Conservation and Research
Garter Snakes are important subjects in herpetological research, focusing on their population dynamics, live-bearing reproduction, and unique ability to resist the toxins of certain prey species, such as newts.