Garter snakes are among the most common snakes in North America,
with a range spanning from Canada to Florida. Often kept as pets,
they are relatively harmless, although some species do possess a
mild neurotoxic venom. However, it is not dangerous to humans.
no secret that snakes shed their skin. Here, a common garter
snake mugs for the camera.
Credit: David Duneau
Where did the garter snake get its funny name? According to
Doug Wechsler, a wildlife biologist at the Academy of Natural Sciences
of Drexel University in Philadelphia and author of "Garter
Snakes" (Powerkids, 2001), their stripes resemble garters men
used to wear to hold up their socks. Another theory is that it is
a corruption of the German word for "garden." Garter snakes are
sometimes erroneously called "garden snakes."
Garter snakes come in a wide variety of colors depending on
the species, but "most have three longitudinal stripes one
in the center of the back and one on each lower side of the body,"
according to herpetologist Jeff Beane, collections manager of amphibians
and reptiles at the North Carolina
Museum of Natural Sciences. "In most species, the stripes are
yellowish or greenish, but this varies with species and region."
Some garter snakes have intricate splotchy patterns between
their stripes, making them look checkered. And their appearance
really does depend on the species Beane pointed out that
some garter snakes are "virtually stripeless."
Garter snakes are relatively small, usually between 23 and 30
inches (58 and 76 centimeters), though sometimes growing as long
as 5 feet (1.5 meters). Beane described them as "slender to moderately
stout-bodied ... [with scales that are] obviously keeled," meaning
they have a ridge down the center. He added that many species of
garter snakes have two-colored tongues.
non-venomous snakes are the most common reptile in Wyoming's
Yellowstone National Park. They live near water and eat small
rodents as well as tadpoles, snails and leeches.
Credit: U.S. Fish and Wildlife Service
Beane described garter snakes as "generalists, inhabiting a
wide variety of habitats." They live in woodlands, meadows and grassy
knolls and like to be near water, especially "in the arid parts
of the West," Beane said.
The common garter snake occurs throughout North America, from
the Atlantic Ocean to the Pacific Ocean and into southern Canada,
according to the Virtual
Nature Trail at Pennsylvania State University New Kensington.
The garter snake is abundant in the eastern United States; it
is the state
reptile of Massachusetts.While no snakes are known to be native
of Alaska, a road-killed specimen of a garter snake was found near
Haines, Alaska, in 2005, according to an article in the Journal
of Herpetology. Researchers who identified the snake through
mitochondrial DNA concluded that the single snake represented a
relict, or remnant, population, a recent natural colonization or
a fresh introduction.
Garter Snake (Thamnophis sirtalis)
Garter snakes are generally active during the day. Beane described
them as "relatively fast-moving [and] highly terrestrial, but [some]
may climb into shrubs or vines; some species climb more than others."
ARKive Initiative pointed out that some species are also excellent
When threatened, garter snakes give off a bad-smelling musk.
Because of their small size, garter snakes have many predators,
including hawks, crows, bears, bullfrogs, snapping turtles, foxes,
squirrels and raccoons, according to the Animal
Diversity Web (ADW), a database maintained by the University
of Michigan's Museum of Zoology.
Cold-climate garter snakes hibernate during the winter. They
hibernate in dens in large groups, with hundreds of garter snakes
sometimes found together (and sometimes other snake species, according
to Beane). According to the Virtual Nature Trail, one den in Canada
was the hibernation spot of more than 8,000 snakes. Garter snakes
will travel long distances to a communal den for hibernation, according
to the ADW.
Beane said that garter snakes "feed mostly on fishes, amphibians,
and earthworms; other prey are occasionally taken." The snakes immobilize
their prey with their sharp teeth and quick reflexes. The saliva
of some species contains a mild neurotoxin that causes paralysis,
making small prey easier to swallow. Like other snakes, garter snakes
swallow their food whole, according to the ADW. Beane said "some
larger prey may be dragged and chewed until killed by trauma."
While most species are classified as harmless (non-venomous),
their bite can cause minor swelling or itching in humans, and anyone
bitten by a garter snake should clean the bite thoroughly. It is
not ultimately a cause for concern. Allergic reactions to the saliva
have been known, but cases are extremely rare, according to the
Garter Snake (Thamnophis sirtalis parietalis)
According to Beane, the best situations for mating are "when
they emerge [from hibernation] in the spring and also when they
congregate again in fall ... because they are already gathered together
for hibernation and do not have to waste energy seeking mates."
But for garter snakes in more temperate areas where they don't hibernate,
the snakes rely on pheromones.
Female garter snakes give off pheromones to attract males. Dozens
of males will come to one female, which is why homeowners sometimes
think garter snakes are overrunning
their neighborhoods. According to the biology department at
College, this mass of mating snakes is called a "mating ball."
Some males use trickery to confuse their competition, according
to Reed College. They will secrete female pheromones to lure other
males toward them rather than to the female. After the other males
are away from the mating ball, the males posing as females will
dart back to the female to attempt to mate. [Related:
Estrogen Turns Male Snakes Into Same-Sex Charmers]
Garter snakes are ovoviviparous, meaning they bear live young.
After mating, females store sperm in their bodies until they want
to fertilize their eggs. Garter snakes give birth to 20 to 40 live
young at a time, though Beane pointed out that litter sizes can
vary greatly. "As few as five and as many as 101 have been reported,"
he said. Parent snakes do not care for their young.
There are 30 species of garter snakes and many more subspecies,
according to the Integrated
Taxonomic Information System. The taxonomy of garter snakes
Species: 30, including:
Thamnophis sirtalis (common garter snake): The common
garter snake has the largest range, occurring in most of the continental
United States with several subspecies, according to Beane. They
are found everywhere from Alaska to Florida, though they do not
live in the Southwest. Common garter snakes usually have three white,
yellow, blue, or green stripes running the lengths of their brown
or olive bodies. Their heads are darker than their bodies.
Thamnophis sirtalis sirtalis (Eastern garter snake):
This subspecies of common garter snake is typical throughout the
eastern United States. Though its body color may vary from brown
to green, it almost always has three yellowish stripes on its back,
according to the Savannah
River Ecology Laboratory. Sometimes its body is splotchy, giving
it a checked appearance. Eastern garter snakes in Georgia and Florida
sometimes have bluish coloring.
Thamnophis sirtalis parietalis (red-sided garter snake):
This California subspecies of common garter snake can be stunning.
Blue or yellow stripes pop against the dark olive or black body,
and red bars line the sides of the body. The red-sided garter snake
has a red or orange head and a blue underside. North of the San
Francisco Bay Area, the underside is sometimes a brilliant bright
blue. Its eyes are larger than other garter snake species. According
Herps, it is able to eat Pacific newts, which are poisonous
to other predators.
Thamnophis sirtalis tetrataenia (San Francisco garter
snake):According to California
Herps, this San Francisco peninsula snake has a red head, big
eyes, and wide, blue-green, black, and red stripes. Its underside
is blue-green. Like the red-sided garter snake, it eats Pacific
Thamnophis marcianus (Checkered garter snake): This small,
southwestern snake has a dark checkered pattern over its entire
body, plus three thin light-colored stripes, according to Herps
of Texas. It is rarely longer than 2 feet.
Thamnophis sirtalis annectens (Texas garter snake): This
common garter snake subspecies primarily resides in the Lone Star
State, though according to Wildlife
North America, there is a population in Kansas. It has a dark
colored back with a bright red stripe down its center and two light-colored
stripes on its sides.
The International Union for the Conservation of Nature's Red
List of Threatened Species lists common garter snakes as "least
concern" for threat of extinction, noting their wide range and population
size, estimated to be more than 1 million adults in the wild.
Fish and Wildlife Service lists the San Francisco garter snake
is listed as "endangered" because it is threatened by habitat loss