by Diane Constable

The common garter snake (Thamnophis sirtalis) is non-venomous and one of the most common snakes found in our area. It prefers to live near a water source and can be found in fields, grasslands and lawns. It is cold-blooded, and hibernates during the winter, often in large groups. If frightened, a garter snake will usually flee, or tuck its head and wave its tail around. The garter snake is covered with tiny scales made of keratin (as are our nails, hair and skin) and moves about in an “s” pattern. It also can climb trees and swim.

Around April, these snakes come out of hibernation and are ready to breed. Each gender has its own scent, but some males may produce both scents. This confuses other males and gives the dual-scented male a better chance to mate with the female. Once mated, the female can hold on to the sperm for up to a year before giving birth, but usually she gives birth sometime between July and October. Unlike many species of snakes, she does not lay eggs. The 15-40 babies are born live and the 8-to-9-inch babies are immediately on their own. About 50% of the babies make it through the first year, and will live two to four years. They will grow up to 3 or 4 feet long, shedding their skin for a larger size as they grow. They face the danger of being eaten by many birds, foxes, raccoons, skunks, other snakes, snapping turtles, and bullfrogs.

The garter is carnivorous, and eats a variety of food, including worms, slugs, frogs, leeches, many types of insects, as well as mice, and other small rodents. The adult garter snake needs a big meal about every two weeks. Because of its diet, it is often thought of as the Gardener’s Friend.

Like all reptiles, it is cold-blooded and needs warm temperatures and sunshine to stay warm. It also needs to be warm to digest its food, or the food can rot in its stomach, causing death.

The garter snake is very sensitive to ground vibrations and has the ability to “hear” these vibrations. Its eyesight is good up to about 15 inches. If farther than that, it can see movement or feel the vibrations, so if a prey stays still, the snake cannot locate it.

Fun Fact

A garter snake does not smell through its nose. It uses its tongue by flicking it in the air for chemical clues. The information then goes to an organ in its mouth called the vomeronasal organ, which allows it to smell.

As an avid photographer, Diane Constable regularly puts her formal education in both nature and photography to good use. Diane also enjoys gardening and her dogs. She serves on the board of the Ann Arbor Dog Training Club and is editor of the club’s newsletter.