Garter Snakes, like all snakes, are carnivorous. Their diet consists of almost any creature they are capable of overpowering: slugs, earthworms, leeches, lizards, amphibians (including frog eggs) minnows, and rodents. When living near water, they will eat other aquatic animals. The Garter Snake in particular favors frogs (including tadpoles), readily eating them despite their strong chemical defenses. Food is swallowed whole. Garter Snakes often adapt to eating whatever they can find, and whenever, because food can be scarce or abundant. Although they feed mostly on live animals, they will sometimes eat eggs.
Being heterothermic, like all reptiles, Garter Snakes bask in the sun to regulate their body temperature. During brumation (the reptile equivalent of hibernation), Garter Snakes typically occupy large, communal sites called hibernacula. These snakes will migrate large distances to brumate.