Photo courtesy of the National Park Service
The red-sided garter snake is the most widely distributed reptile species in North America. It lives further north on the continent than any other reptile species! Garter snakes, like other reptiles, are cold-blooded. This means that their body temperature changes depending on the temperature of the air around them. Humans, on the other hand, are warm-blooded. Our bodies stay pretty much the same temperature, no matter what temperature it is outside. During the warmer summer months garter snakes are active (depending on the temperature and the time of day) and during the colder winter months they hibernate.
Snakes have unusual habits when they are hibernating. They come together in large groups, often a few hundred snakes, but sometimes many thousands of them (8,000 were counted at one time in a den in Manitoba , Canada), and hibernate in the same underground space. This space is called a hibernaculum. Spending the winter very close together allows the snakes to share body heat and stay warmer than they would be on their own. In the spring, when temperatures start to warm up, the snakes emerge from their dens and migrate to their summer homes. Scientists have tracked snakes migrating up to 12 km (about 7.5 mi) away from their hibernaculum. Snakes will often return to the same den year after year.
Takats, Lisa. Red-sided Garter Snake (Thamnophis Sirtalis Parietalis) Relocation and Education Project. Alberta Sustainable Resource Development, Fish and Wildlife Division, 2002. (See above link)