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Snakes have a bad reputation. Calling someone a snake or a snake in the grass is an insult. Declaring that someone speaks with a forked tongue means the person says one thing but does another. A cold-blooded person, alluding to snakes’ cold-blooded nature, is someone who lacks compassion.
But not all snakes deserve a bad rap. The little garter snakes (hamnophis sirtalis sirtalis) we encounter in our daily lives are chief among them. Our eastern garter snakes are easy to recognize, with three yellow stripes that run along their otherwise dark body. Because they are cold-blooded, you might see them sunning on a rock on a warm day.
One reason to let garter snakes off the hook is that they are harmless to humans. Garter snakes’ first line of defense when they notice a human is to leave as quickly and silently as possible, as noted by James Whitcomb Riley in his poem “A Country Pathway:”
A garter-snake across the dusty trail
Glances and — is not there.
People once thought garter snakes did not have venom, but by the 1980s scientists discovered this is not true. Their venom is just not strong enough to harm people (frogs or earthworms are not that lucky, however).
Many snakes lay eggs, but garter snake females, which grow larger than males, give birth to live young. Inside the female’s body, the snakes hatch out of their egg sacs into five-inch babies just before they are born. They will grow for as long as they live, up to three feet in length, though they’ll grow only a couple of inches in their first year.
So, how do these snakes capture prey? They do not have legs or claws to hold prey. They do not have teeth and jaws that can rip or tear. Garter snakes use tiny amounts of venom. Because garter snakes do not usually eat insects, much of their diet in Massachusetts is earthworms. If they happen to capture a larger amphibian such as a frog, they need just enough venom to stun or slow it down. These snakes do not have fangs for injecting venom. Instead, they produce toxin near the back of the upper jaw. The toxin mixes with saliva in the mouth and reaches prey slowly through bite wounds as the snake hangs on and chews.
In the spring, garter snakes end their period of winter inactivity (called brumation). When ready to mate, a female garter gives off chemical scents called pheromones to attract males. And does this ever work! The competition is so intense that there are such things as mating balls — writhing mass of snakes where many males compete to mate with one female.
Perhaps unsurprisingly, snake lungs are not like human lungs. Snake lungs are long skinny tubes that stretches the length of the snake’s body. The ribs and the rib muscles expand to pull in air and contract to push out air. When a male snake attempts to mate with a female, his muscle contractions may push air out of the female’s body, leaving only oxygen-poor air in her lungs. The stress response to lack of oxygen is to open the cloaca (the exit chamber for fecal waste, urine, and the reproductive tract). This makes it easier for the male to mate, which he does using one of his hemipenes. Garter snakes, like other snakes, have paired reproductive organs. Male garter snakes alternate between the right and left organ if they mate multiple times. You can look for the reproductive organs to determine the sex of a garter snake.
But garter snakes may redeem themselves through the many unique features they possess that makes them different from other snakes. For instance, unlike many other snakes, garter snakes are social and are even known to form friendships. They might warm themselves in a large group, and if you happen upon them, they will take off at once in all directions. (This has happened to me as I rounded a bend in the Fells. I’d like to say I was unfazed, but, no. Sound escaped my lips.)
Garter snakes gather in groups for safety, to stay warm, to retain moisture and to communicate. But these groups are not random. Garter snakes group intentionally with specific snakes. In one study, scientists placed garter snakes into four groups of 10 and let them rearrange themselves into smaller groups. Snakes were identified by colored dots on their heads. Twice per day, researchers removed the snakes, cleaned the enclosure to erase odors, and then shuffled the snakes around. The snakes returned to their preferred groupings of three to eight snakes each time they were shuffled.
Their sociability also seems to give them other abilities. A 2024 study showed that garter snakes can recognize themselves. You have probably seen videos in which a researcher places a mirror in front of a chimp or an elephant, and the animal recognizes itself in the mirror. ] For animals that are not primarily visual, such as dogs and reptiles, scientists use another method to gauge self-recognition: They present the test animal with its own odor (for example, a urine sample) and an odor from another animal of the same species. If the test animal sniffs its odor longer than the stranger’s odor, it passes the test, demonstrating recognition of its own odor, and by extension, itself.
Scientists conducted this experiment with garter snakes and ball pythons, which are tree-dwelling ambush predators who live alone. Garter snakes passed the self-recognition test, but ball pythons did not, and scientists speculate that recognizing themselves may help garter snakes navigate their complex social relationships. With such profound abilities, should we perhaps reconsider the slew of snake-related insults? Their physical features are much different than ours, but like us, garter snakes choose their companions, recognize themselves, and have a complex social life.
A stronger
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