Common Garter Snake: The Gardener's Friend

Common Garter Snake, Thamnophis sirtalis The Common Garter Snake, Thamnophis sirtalis, often referred to as a garden snakes or as a gardener snakes, can be found in a wide variety of habitats which may include our own backyards. The Common Garter Snake tends to prefer wet, grassy environments but are highly adaptable and can survive the ever-changing weather conditions we experience in Wisconsin. Some may refer to these creatures as pests, while others enjoy having them slither through their gardens. There are many benefits to sharing our neighborhood with these reptiles.

Many people report significant benefits to having Common Garter Snakes in their yards. They are seemingly a natural pest control. Common Garter Snakes feed on earthworms, snails, grasshoppers, ants, crickets, and occasionally, rodents. Many of the insects Common Garter Snakes feed on are the ones feasting in our gardens.

While it’s hard not to let out a squeal when you stumble upon one, garter snakes are more afraid of us than we are of them.

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Common Garter Snake
Thamnophis sirtalis
Lifespan Average 4 years,
but up to 10 years
Weight 1 pound
Average Size 18-27 inches
Color 8 longitudinal yellow
stripes on dark body
Sexual Maturity Males: 1.5 years
Females: 2 years
Mating Sytle Promiscuous
Gestation: 2-3 months
Number of Young 10-40 snakelets
Snakelet Size 5-8 inches
Diet Toads, Frogs, Slugs
Worms

Description

Common Garter Snakes are highly variable in color pattern. They typically have eight yellow stripes that run along the length of their body on a black, brown, gray, or olive background. The stripes may also be white, blue, greenish, or brown. One stripe runs down the center of the snake's back, the other stripes run alongside this central stripe. Sometimes the stripes are absent or poorly defined. Some garter snakes have alternating rows of dark spots that run along the stripes, making the stripes look more like checkerboard patterns of light, rather than lines.

Common Garter Snakes have a head that is wider than the neck and is uniformly dark. Their tongues are red, tipped in black, and their scales are keeled (with a raised ridge along the length of the scale). The chin, throat and belly resemble the stripes in coloration, ranging from white to yellow, greenish, blue, or brown.

Common Garter Snakes grow, on average, to be 18 to 27 inches in length. Males are generally smaller than females and have longer tails. Young Common Garter Snakes are born at 5 to 8 inches in length and are similar in appearance to the adults.

Many people report significant benefits to having Common Garter Snakes in their yards. They are seemingly a natural pest control.

Habitat

Common Garter Snakes are very widespread, highly adaptable and can survive extreme environmental conditions. Common Garter Snakes are found in a wide variety of habitats, including meadows, marshes, woodlands, and hillsides. They tend to prefer moist, grassy environments.

The common garter snake is most often found around aquatic habitats, such as ponds, freshwater wetlands and riparian areas. If threatened, they will often flee into the water where they are excellent swimmers. In urban areas they are found where there is cover such as debris, boards, vegetation, logs, or rocks.

Reproduction

These snakes begin mating in the spring as soon as they emerge from hibernation. The males leave the den first and wait for the females to exit. Common Garter Snakes are polygynandrous (promiscuous) which means that both males and females mate with multiple partners. Their breeding season occurs in spring soon after emergence from hibernation and in the fall. Many males may try to mate with one female, resulting in a "breeding ball".

After the female has chosen her mate and mated, she returns to her summer habitat to feed and to find a proper birth place. However, the males stay to re-mate with other available females. The females have the ability to store the male's sperm until it is needed and thus a female may not mate if she does not find a proper partner.

Males become sexually mature at 1.5 years and females become sexually mature at two years.

Female Common Garter Snakes nurture their young in their bodies until they are born. The mother gives birth to live young, called snakelets; she doesn't lay eggs. Newly born snakes tend to stay around their mother for several hours or days but she provides no parental care or protection after they are born.

Social Life

Graphic of snake anatomy

Common Garter Snakes are generally solitary but may gather in groups when they brumate. Brumation is known as the hibernation for cold-blooded animals. Snakes depend upon their environment to regulate their body temperature. Cold temperatures cause snakes to hide underground, in rock crevices and in burrows to stay warm and safe. Their activity, body temperature, heart rate and respiratory rate drops like in hibernation. During brumation, snakes are mostly asleep but still can wake up to drink water.

Common Garter Snakes brumate in large groups during the winter in their dens which are usually located in rock outcropping or even abandoned mammal burrows.

Lifespan

The average lifespan of wild Common Garter Snakes is approximately 4 years but they may live up to 10 years.. Most Garter Snakes probably die in their first year of life.

Diet

Common Garter Snakes typically eat earthworms, amphibians, leeches, slugs, snails, insects, crayfish, small fish and other snakes. They seem immune to the toxic skin secretions of toads and can eat them without harm. Occasionally small mammals, lizards, or baby birds are eaten as well. Common Garter Snakes find their prey using their excellent sense of smell and their vision.

They use several different hunting methods, such as peering, craning, and ambushing to capture their prey. The different techniques describe the way the snakes move while they hunt. They immobilize their prey using their sharp teeth and quick reflexes. The saliva of Eastern Garter Snakes may be slightly toxic to some of their small prey, making it easier to handle them while they are being eaten. Like other snakes, they swallow their food whole.

Communication

Juvenile Common Garter Snake, Thamnophis sirtalis Common Garter Snakes communicate with each other primarily through touch and smell, especially for breeding. Outside of the breeding season they do not interact much with other snakes. They use their forked tongues to collect chemicals from the air and insert these forks into a special organ in the roof of their mouth, which interprets these chemical signals, called pheromones.

Pheromones can be used as a tracking device for garter snakes. Using their acute sense of smell, Common Garter Snakes can locate other snakes or trails left behind by other snakes through the pheromones given off by their skin. After they are born, baby snakes follow the same pheromone trails to feed and locate other Common Garter Snakes.

Snakes are also sensitive to vibrations and have reasonably good vision.

Predators

Common Garter Snakes are eaten by a wide variety of predators, which varies throughout their range. Large fish, bullfrogs, snapping turtles, milk snakes, American crows, hawks, great blue herons, raccoons, foxes, squirrels, and shrews are some of the animals that prey on Common Garter Snakes. They rely on stealth and camouflage for protection, and will flee into water to escape predators on land. Their stripes make them difficult to see properly and capture in grassy areas.

If unable to flee they coil to make themselves appear larger, and may strike and bite. If grabbed, these snakes writhe and release a foul-smelling secretion; they will also urinate on their attacker

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