A garter snake is any one of a number of different snakes of the genus Thamnophis. On average, garter snakes are between two and five feet long, and may be gray, green, yellow, brown, or black in color, with stripes that run lengthwise across their bodies. Garter snakes are among the most common snakes in North America, with a natural habitat that ranges from Central America to Canada. Although garter snakes are frequently believed to be nonvenomous, they actually do produce small amounts of a mild venom that is essentially harmless to humans. Garter snakes are predators, but they also are hunted by a wide range of other species, including larger snakes, predatory birds, raccoons, badgers, and domestic cats.
The diet of the garter snake is quite varied, which is one of the reasons the snakes thrive in so many different climates. In general, the garter snake is a carnivore, preferring to eat insects, amphibians, rodents, fish, small reptiles, and occasionally, eggs. Some larger garter snake species may be able to hunt larger prey, such as small fowl. Garter snakes do not constrict their prey like boas do; instead, they stun the prey or, more rarely, kill it outright before eating it. Prey is always swallowed whole and often while still alive.
Many varieties of garter snake hibernate during the cold months of the year, particularly those garters living in Canada and the Northern United States. These snakes increase their food intake during the latter part of the summer to prepare for hibernation. They then migrate to a designated hibernation den, where they spend the winter with hundreds of other snakes. When warmer weather arrives, the temperature within the den slowly rises and the garters slowly rouse themselves, not fully emerging from hibernation for a period of two weeks or more. In some garter snake species, the hibernation period instigates mating behaviors in the snakes.
Garter snakes usually mate in the spring, and sometimes also in the fall, with the females storing the sperm until the spring in case they are unable to mate. Male garter snakes emerge from hibernation before females do, so that they can be ready to mate when the females finally emerge from the den. Female garters give birth to litters of live young, usually in the late summer months.
While some people see garter snakes as pests that invade their basements and gardens, others keep garters as pets. Due to their opportunistic feeding habits and relatively tranquil constitution, garters make good pets for children or people who have never kept snakes before. In captivity, garter snakes often subsist on a diet consisting of slugs, frozen or fresh fish, leeches, and earthworms. They gradually adjust to being handled by humans, although because the snakes are so slender and delicate, young children must be taught to handle them with gentle care.