Monday, November 21, 2011

Garter Snakes

Garter Snakes are without a doubt one of the most widely spread of all the reptiles found in North America. In fact the Common Garter Snake(Thamnophis sirtalis) is the only snake known to be hardy enough to survive in Alaska’s inhospitable climate. It is thought to be the northernmost snake in the World with exception to a snake called the Crossed Viper (Vipera berus). In Missouri where I live I find several varieties in my yard, but one of the most common by far is the Eastern Garter Snake (Thamnophis sirtalis sirtalis) which is pictured here above. They reach lengths up to 26 inches. As far as I know all garter snakes have the tell-tale stripes that run dorsally along their bodies. These stripes may be green, yellow, gray, black, red and even blue. The subspecies the red-sided garter snake (Thamnophis sirtalis talis parietalis) is the most prevalent of the two species I find. Red-sided garter snakes are quite striking in their appearance with bright red color patches between the stripes.

Garter Snakes are colubrid snakes in the family Colubridae; over 2/3 of the snakes found in the world belong to this family, making it the largest family of snakes. This group of snakes is often described as a catch all for snakes that don’t quite fit into other families. Most within this family are non-venomous, but a few however have venom toxic enough to cause human fatalities such as the Boomslang, Twig Snake and snakes in the genus Rhabdophis which are found in Asia. Garter snakes do posses venom glands, but these glands are located  posterior (to the rear) of the snake’s eyes whereas typical venomous snakes have venom glands located anterior or forward. The venom they posses is not lethal enough to affect humans and the garter snake lacks any real way of injecting you with it anyway. The venom is used to subdue prey rather than as a defense mechanism.  Once the snake has captured its prey it will “chew” the venom into the unfortunate victim.

Garter snakes commonly prey on frogs, toads, small rodents, birds, slugs, lizards, leeches, earthworms, and fish. Since the majority of their diet consists of aquatic creatures they will most often be found in those environments. We have a large goldfish pond and that is usually where I find these snakes. They commonly feed on the toads and bullfrogs found near or in the pond. This photo was taken a few years ago near the pond. This red-sided garter snake (above and below) had captured a large toad and was doing its best to swallow it. There was quite a struggle taking place, almost like tug-o-war. The snake pulling with its mouth, and the toad pulling with its legs in the other direction. The toad was finally able to free itself from the snake and quickly hopped off to lick its wounds.

I swear the toad looks ANGRY in this photo….as if indignantly saying “How dare this snake try to eat me!!!!”

Garter snakes are one of the testiest snakes in the reptile world. For a snake that averages 2 feet in length and lacks any significant venom, it more than makes up for it in attitude. Of all the snakes I’ve handled I’ve been bitten and musked more by this species than any other. This past spring while doing an interpretive hike with a group of first grade students, one of the fathers noticed a snake along the side of the trail. He pointed it out to me in case I wanted to show the kids. With 25 kids, plus parents in the group I was afraid the snake would slither away before all the kids could see it. So I choose to catch the snake and show the kids……BIG MISTAKE! As soon as I had the snake in hand it chose that moment to musk me. I was literally covered from chest to toe with white, stinky musk!!!! Talk about smell bad! The kids all let out a loud EWWWWW! I quickly put the snake down and told the kids “This is why we should not handle wild snakes.” It was a lesson learned for all of us, albeit a stinky one!

While this snake(above) appears to be smiling, it was definitely doing its best to warn me away. He was lunging and biting at me in a very intimidating way. I managed to capture an image with its mouth open and tongue hanging out before finally leaving it in peace. This illustrates my point about the attitude these snakes possess.


All snakes use their tongue to smell the World around them. They flick it in and out of their mouth scraping it across an organ in the roof of their mouth called the Jacobson Organ. This organ picks up scent particles off the tongue as it is brought back into the mouth. The snake is able to determine if what it is smelling is food, or foe. Snakes do not possess ears for the outside world (although a snake with ears would be seriously cool). They “hear” their surroundings through vibrations felt in their jaw bones. Humans walking around in a snakes world must sound like giants to the snake. They almost always feel us coming and get out of the way long before we even know a snake was there.  Snakes lack eyelids and cannot blink their eyes to protect them from injury, they instead have a thin scales over their eyes. The scales are shed each time the snake sheds it old skin. Snakes shed several times a year, but much depends on how much the snake is eating and how much it is growing. Snakes that are feeding on a regular basis will shed more often than those that find it difficult to find food. This is often why wild snakes shed fewer times annually than pet snakes. Wild snakes have to sit and wait for food to come within reach, or they will go in search of food. This is not as easy as it sounds. A snake may smell a rodent trail, and sit and wait motionless for a rodent to pass by. They are capable of remaining motionless for many hours. Snakes may go many weeks or even months without feeding. They have a slower metabolism than mammals and are able to go without food for long periods of time. A large meal may last a snake for several weeks before it feels the urge to feed again. Snakes are also cold blooded and must warm themselves in the sun. Being heterothermic means the snakes body is the same temperature as its surroundings. It must therefore find a suitable location to bask itself before it is able to move and feed properly. I describe it as “A Cold Snake, is a Slow Snake and a Slow Snake is a Dead Snake.” A warm snake can flee from predators and digest its food. A cold snake is slow and unable to move quickly out of dangers way, and will often regurgitate its meal should it try to eat.

Garter snakes mate in the spring in accordance with their emergence from brumation. Reptiles generally begin brumation in late fall (more specific times depend on the species). They will often wake up to drink water and return to “sleep”. They can go months without food. Reptiles may want to eat more than usual before the brumation time but will eat less or refuse food as the temperature drops. However, they do need to drink water. The brumation period is anywhere from one to eight months depending on the air temperature and the size, age, and health of the reptile. During the first year of life, many small reptiles do not fully brumate, but rather slow down and eat less often. Brumation should not be confused with hibernation; when mammals hibernate, they are actually asleep; when reptiles brumate, they are less active, and their metabolism slows down so they just do not need to eat as often. Reptiles can often go through the whole winter without eating. Brumation is triggered by cold weather, lack of heat, and the decrease in the amount of hours of daylight in the winter.

In the case of garter snakes the males generally leave the hibernacula first and sit in wait for the females to come out. These emergence’s may contain 100′s of individual snakes. The female emits a strong pheromone that entices the males to compete for mating privileges. It is not uncommon for dozens of males to fight and vie for the attention of one female. Once mated, the females are capable of retaining the males sperm for years and therefore can delay fertilization if they so choose. The female incubates the eggs within her body until the babies are ready to be born. She will then give birth to live young. The litter size can vary from as few as 3 young to as many as 80, depending upon the age of the snake, how healthy the snake is and the species it is. The record litter size for garter snakes is 98 offspring. Juvenile snakes are independent at birth. They require no special help or skills from their parents and are armed with all the instincts they need to survive. They are however vulnerable at this stage and often fall victim to predators such as large frogs, birds, raccoons, foxes and other snakes. Those that survive may live up to 15 years or more.

Garter snakes have often been sought after in the pet trade, mostly because they are strikingly beautiful creatures, but also because they are so easily found. Garter snakes are known to emerge in the spring in heavy numbers all at once, so anyone bent on capturing them, just locates a hibernation site and visits it in the spring. Many garter snakes have been removed from the wild in this fashion. Even though 1,000′s have been captured from the wild , their numbers are still stable to high in most all their range. There is an exception in California, the San Francisco Garter Snake (Thamnophis sirtalis tetrataenia) is listed as Federally endangered. Even though the majority of garter snakes would be considered common, they are still beautiful examples of snake fauna. They are beneficial in the garden by keeping slugs, leeches, rodents and other creatures under control. They are also an important component in the food chain providing food for many other animals. All snakes should be tolerated and respected for the good that they do. Many of us may not like snakes, or perhaps we’re scared of them, but this should never be an excuse to kill one.


  1. Very informative. Call me crazy, but is that a reference to Labyrinth in there?

  2. Thanks for using and explaining the word "brumation". I usually find gartersnakes to be fairly calm in hand but recently one musked me and then made a vigorous attack on my boot as I set it down. One summer as we were hiking the Lost Coast of California, we found garter snakes in every single little stream pouring out to the ocean. They were so agile in the water. There are San Francisco gartersnakeson the property across the road from the Dipper Ranch and occasionally I see them. Beautiful!

  3. “This is why we should not handle wild snakes.” - Seriously, I love that!:) Garter snakes are ideal pets because, one, they're diurnal (we can watch them all day and night), and two, they're harmless. Source:

  4. Thanks Michael for visiting and leaving a comment. Garter snakes are one of those snakes that are common, but still beautiful to look at. They can be feisty though, I've been bitten more by these snakes than any others. When that garter poo'ed on was all I could do to not laugh out loud, but I had to use it as a learning op.