C
Species Profile

Checkered Garter Snake

Thamnophis marcianus

Checkerboard swimmer of the Southwest
James Brunner Photography/ via Getty Images
Checkered Garter Snake, Common Garter Snake, Animal, Animals In The Wild, Close-up

At a Glance

Wild Species
Diet Carnivore
Activity Diurnal+
Lifespan 4 years
Weight 0.2 lbs
Status Least Concern
Did You Know?

Adults are typically ~46-107 cm total length (TL) (Stebbins & McGinnis, 2018; Ernst & Ernst, 2003).

Scientific Classification

A medium-sized North American natricid snake (garter snake) characterized by a distinct checkerboard pattern of dark blotches along the back, typically with pale longitudinal stripes. Non-venomous (no medically significant venom) and generally harmless to humans.

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Natricidae
Genus
Thamnophis
Species
marcianus

Distinguishing Features

  • Prominent dark checkering/blotches between or alongside dorsal stripes
  • Slender-bodied garter snake with keeled scales typical of natricids
  • Often found near water; diet commonly includes amphibians, small fish, and invertebrates

Physical Measurements

Males and females differ in size

Length
♂ 1 ft 11 in (1 ft 4 in – 2 ft 6 in)
♀ 2 ft 6 in (1 ft 8 in – 3 ft 7 in)
Weight
♂ 0 lbs (0 lbs – 0 lbs)
♀ 0 lbs (0 lbs – 1 lbs)
Tail Length
♂ 6 in (4 in – 8 in)
♀ 5 in (4 in – 7 in)

Appearance

Primary Colors
Secondary Colors
Skin Type Thamnophis marcianus has keratinized reptile scales, strongly keeled dorsal scales and broad ventral scutes for movement. Its skin often looks wet or glossy near water, including irrigation canals.
Distinctive Features
  • Adult Checkered Garter Snakes (Thamnophis marcianus) are usually about 46–91 cm long, but some grow up to about 112 cm; sizes vary by region.
  • Slender, medium-sized natricid build with a relatively small head and round pupils; mildly venomous (rear-fanged) but not dangerous to humans, with bites typically causing at most minor local irritation.
  • Very prominent dorsal checkering (dark squares/rectangles) is the key field mark distinguishing it from many other Thamnophis in the same region, especially where stripes alone are less diagnostic.
  • Pale mid-dorsal stripe typically present; lateral stripes usually occur on the sides above the belly edge; stripe brightness (cream/yellow) varies by individual and locality.
  • Frequently associated with water or damp habitats in arid landscapes (streams, irrigation ditches, ponds, riparian corridors); commonly observed swimming or basking close to water-appearance often includes mud/water sheen from habitat use.
  • Defensive behavior often includes flattening the body, rapid escape into water/vegetation, and releasing musk/feces; this is typical of Thamnophis and often noted in field accounts for T. marcianus.
  • Keeled dorsal scales create a visibly roughened texture compared with smooth-scaled snakes; this is often apparent in close photographs as fine ridging along each scale.
  • The Checkered Garter Snake (Thamnophis marcianus) has an unknown wild lifespan, often cut short by predators; they live much longer in captivity, but exact oldest ages are reported differently.

Sexual Dimorphism

Like other garter snakes, Thamnophis marcianus shows sexual dimorphism: females are usually larger and heavier for more eggs, while males have longer tails (contain hemipenes) and often look slimmer. This is seen in wild and museum samples.

♂
  • Proportionally longer tail length (relative to total length) with a more gradual taper past the cloaca.
  • Typically slimmer body profile than gravid/large females.
  • Seasonally, males may show more frequent surface activity during mate-searching periods (a behavioral correlate often reported for Thamnophis; included here as an externally observable difference in encounter patterns).
♀
  • On average larger total length and notably greater girth, especially when gravid (live-bearing species).
  • Shorter tail proportion relative to total length; abrupt taper compared with males.
  • During late gestation, body appears markedly distended in the posterior half, an obvious externally visible seasonal change.

Did You Know?

Adults are typically ~46-107 cm total length (TL) (Stebbins & McGinnis, 2018; Ernst & Ernst, 2003).

The "checkered" look comes from dark, squarish dorsal blotches between/along pale longitudinal stripes-excellent camouflage in patchy shoreline vegetation.

It is viviparous (live-bearing). Reported litter sizes are commonly in the single to few-dozen range; sources summarize litters at roughly ~6-29 young (Ernst & Ernst, 2003).

A strong swimmer, it often hunts at the water's edge for small vertebrates and invertebrates (e.g., amphibians, small fish, worms/leeches) typical of Thamnophis diets (Ernst & Ernst, 2003).

Like other garter snakes (genus Thamnophis; ~30+ species), it has keeled scales (ridged scales) that give the body a matte look and help with traction on wet banks.

It is harmless to people; if grabbed, it more often relies on rapid escape plus a pungent musk from cloacal glands-classic garter-snake defense behavior reported across Thamnophis (Ernst & Ernst, 2003).

Unique Adaptations

  • Checkerboard dorsal pattern: breaks up the snake's outline in dappled riparian light and patchy vegetation, aiding concealment from predators and prey.
  • Keeled scales: increase friction on slick mud/vegetation and reduce sheen (matte appearance), useful for a shoreline lifestyle (a hallmark of many natricids).
  • Semi-aquatic locomotion: capable of efficient lateral undulation in water and quick transitions between swimming and bank movement.
  • Prey-subduing oral secretions: like other Thamnophis, has mild salivary/duvernoy-gland secretions that help restrain prey but are not medically significant to humans.
  • Broad, opportunistic diet: flexible feeding on seasonal wetland prey (amphibians/fish/invertebrates) supports survival in highly variable Southwestern water availability.

Interesting Behaviors

  • Semi-aquatic foraging: patrols shorelines, slips into shallow water, and hunts along emergent vegetation; commonly uses quick dives as an escape tactic.
  • Basking-and-dash routine: alternates between basking on banks/rocks and rapid retreats into cover or water when disturbed.
  • Scent-trail mate finding: males track females using pheromone trails (a well-documented Thamnophis strategy) and may attempt mating soon after seasonal emergence in suitable climates.
  • Defensive musk display: when threatened, may gape, strike, and smear musk/feces-deterring predators without needing potent venom.
  • Edge-habitat tolerance: frequently occupies human-made waterways (irrigation ditches, canals, stock tanks) when prey and cover are present-behavior that helps it persist in arid landscapes.

Cultural Significance

The checkered garter snake (Thamnophis marcianus) is a nonvenomous, semi-aquatic snake found in wetlands, streams, and irrigation canals. It eats frogs and small fish, is harmless to people, and is called a "beneficial" species in riparian outreach.

Myths & Legends

Hopi tradition includes the Snake Dance and narratives about communion with Snake beings and prayers for rain-ceremonial and mythic roles for snakes tied to water and seasonal renewal (snakes broadly, not a single species).

Puebloan and wider Southwestern folklore includes powerful "water serpent" motifs (often described as horned or guardian serpents) associated with springs, rivers, and rain-reflecting the deep link between snakes and life-giving water in arid lands.

In Mesoamerican mythology, the Feathered Serpent is a creator and culture-hero figure-an enduring serpent symbol across Mexico that shapes how many communities culturally frame serpents as potent, transformative beings.

The name 'garter snake' came from early naturalists who thought the snake's long stripes looked like the fancy garters people once wore to hold up stockings, a fashion link used as its common name.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Stable

Life Cycle

Birth 14 neonates
Lifespan 4 years

Lifespan

In the Wild
0.5–10 years
In Captivity
1–15 years

Reproduction

Mating System Polygynandry
Social Structure Aggregation Group
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Checkered Garter Snake (Thamnophis marcianus) is live-bearing and both sexes mate with multiple partners. Mostly solitary, they form short breeding groups; males follow scent trails and court by touch. Females likely store sperm; no pair bonds or care.

Behavior & Ecology

Social Solitary (temporary congregations at shared refugia/hibernacula) Group: 1
Activity Diurnal, Crepuscular
Diet Carnivore Amphibians (frogs and tadpoles)
Seasonal Hibernates

Temperament

Generally non-aggressive toward humans; typical response is rapid escape into vegetation/water or a refuge.
Defensive behaviors when cornered/handled can include striking/biting and releasing cloacal musk; may also flatten the body and/or hiss (common natricid/Thamnophis defensive repertoire; Rossman, Ford & Seigel 1996; Ernst & Ernst 2003).
Checkered Garter Snake (Thamnophis marcianus) changes activity with seasons: more active on the surface in cooler parts of the day and season, and more active at dawn and dusk in hot weather to avoid overheating.
We don't know exactly how long Thamnophis marcianus lives in the wild. Captive Thamnophis spp. often live about ten years or more with good care.

Communication

Hiss Defensive exhalation; not a true vocal call
Chemical communication via pheromones Skin/lipid pheromone trails and courtship pheromones); males track females with tongue-flicking and vomeronasal (Jacobson's organ) sampling-well documented for Thamnophis (Rossman, Ford & Seigel 1996
Tactile courtship Body alignment, chin-rubbing/pressing and contact-based stimulation) during mating aggregations (Rossman et al. 1996
Cloacal musk release as a defensive chemical signal/deterrent.
Visual/body-posture signaling (body flattening, head positioning) in threat contexts.
Substrate-borne cues (movement/vibration) that can alert nearby individuals at shared refugia, though not specialized 'social' signaling.

Habitat

Biomes:
Freshwater Wetland Desert Hot Temperate Grassland Temperate Forest Mediterranean
Terrain:
Plains Plateau Valley Riverine Rocky Sandy Muddy +1
Elevation: Up to 7545 ft 11 in

Ecological Role

Riparian/aquatic mesopredator (mid-level predator) and prey item in North American wetland and desert-riparian food webs.

Regulates local populations of amphibians and small fishes (top-down control) Consumes aquatic/semiaquatic invertebrates such as leeches and earthworms, linking aquatic and terrestrial energy pathways Serves as prey for higher trophic levels (wading birds/raptors, carnivorous mammals), supporting riparian biodiversity

Diet Details

Main Prey:
Amphibians Fish Annelids Leeches Small reptiles Small mammals

Human Interaction

Domestication Status

Wild

Domestication: none. Checkered Garter Snake (Thamnophis marcianus) is wild. People meet it by chance in wetlands, canals, and urban edges, sometimes in school displays, limited pet trade, and research. Medium, checkered, up to 109 cm. Active day to twilight near water; eats frogs, fish, and invertebrates. Wild lifespan unclear; captive garters often live ~10+ years.

Danger Level

Low
  • Bite is usually superficial; may cause minor bleeding and short-lived localized pain (non-medically significant for most people).
  • Defensive cloacal musk/feces can be released when handled; strong odor and can soil clothing.
  • Zoonotic risk: like many reptiles, can carry Salmonella; risk increases with poor hand hygiene after handling.
  • Rare idiosyncratic reactions: localized swelling/itching after a bite has been reported in some garter snakes due to oral secretions (general Thamnophis/colubroid literature; e.g., reviews of colubrid oral secretions/venom such as Weinstein et al. 2011), but systemic, medically significant envenomation is not expected for this species.

As a Pet

Suitable as Pet

Legality: Checkered Garter Snake (Thamnophis marcianus) is usually legal to own in many U.S. areas, but wild-caught snakes may be banned or need permits. Not listed under CITES; check local laws and prefer captive-bred.

Care Level: Moderate

Purchase Cost: $40 - $200
Lifetime Cost: $800 - $3,000

Economic Value

Uses:
Pet trade (limited compared with more common Thamnophis) Education/outreach (nature centers, schools, interpretive programs) Research value via the broader Thamnophis model system Ecosystem services: predation on amphibians/invertebrates; contributes to wetland food webs
Products:
  • captive-bred individuals for hobbyists/educational collections
  • educational programming/display animals
  • non-consumptive wildlife viewing (local ecotourism/recreation value)

Relationships

Predators 8

Related Species 9

Common Garter Snake
Common Garter Snake Thamnophis sirtalis Shared Genus
Western Terrestrial Garter Snake Thamnophis elegans Shared Genus
Western Ribbon Snake Thamnophis proximus Shared Genus
Plains Garter Snake Thamnophis radix Shared Genus
Black-necked Garter Snake Thamnophis cyrtopsis Shared Genus
Mexican Garter Snake Thamnophis eques Shared Genus
Common Watersnake
Common Watersnake Nerodia sipedon Shared Family
Graham's Crayfish Snake Regina grahamii Shared Family
Dekay's Brownsnake
Dekay's Brownsnake Storeria dekayi Shared Family

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

Western Ribbon Snake Thamnophis proximus Live and hunt in riparian and wetland areas; are mostly diurnal along water edges, feeding on frogs, tadpoles, and small fish. Overlaps with T. marcianus in the U.S. Southwest; both are slender natricids that enter water, flee quickly, and release musk.
Plains Garter Snake Thamnophis radix Ecologically comparable generalist garter snake of open habitats and wet meadows; commonly feeds on amphibians and earthworms and exhibits similar defensive behaviors (flattening the body, musking, striking). Serves as a functional analog where ranges meet or where T. marcianus is absent.
Common Watersnake Nerodia sipedon Fills a similar aquatic-edge role as a shallow-water hunter of fish and amphibians. Although bulkier and more aquatic than Thamnophis marcianus, both are non-front-fanged natricids that share prey and predators such as wading birds and raptors.
Graham's Crayfish Snake Regina grahamii Another natricid strongly tied to aquatic systems, overlapping in use of shoreline cover and submerged vegetation. While Regina grahamii specializes on crayfish, both species occupy comparable trophic positions as small-to-medium, semi-aquatic snake mesopredators and share similar predator guilds (herons, raccoons, larger snakes).
Northern Leopard Frog
Northern Leopard Frog Lithobates pipiens Thamnophis marcianus eats frogs, including northern leopard frogs where they co-occur, and both use shallow freshwater edges with emergent plants, so the snake depends on amphibians and those wet habitats.

Checkered garter snakes can release a stinky liquid to escape predators.

The checkered garter snake is aptly named for the black and white checkered pattern of scales running down its back. Frogs, worms, toads, and small fish are all a part of the diet of this snake. In terms of habitat, this snake can thrive in many places, including savannas, grasslands, woodlands, and deserts. It measures just 18 to 24 inches long. Its small size is just one reason why some people care for these reptiles as pets.

Checkered Garter Snake infographic

4 Amazing Facts

  • A rare albino type of this snake has white/yellow scales and red eyes
  • It gives live birth to as many as 35 snakelets
  • Its venom is deadly to its prey but not to humans
  • It spends winter brumation inside a burrow with several other garter snakes.

Habitat: Where to Find Them

A checkered garter snake raising its head

Checkered garter snakes have round eyes with black pupils.

The checkered garter snake lives in North America and Central America. They are seen in the southwestern United States in Texas, New Mexico, and Arizona. Mexico is also home to this snake. Belize, Costa Rica, Guatemala, Honduras, and Nicaragua are other places to find the checkered garter snake.

Checkered garter snakes live in a temperate climate. They’re found in varied habitats, including savannahs, deserts, woodlands, and grasslands. It’s not unusual to spot these snakes near rivers, ponds, and streams.

The activity of this snake increases during mating season in the spring, specifically from late March to April. Alternatively, they disappear into rock crevices and abandoned burrows in the wintertime to brumate with other garter snakes.

Countries where the checkered garter snake lives:

  1. United States
  2. Mexico
  3. Guatemala
  4. Costa Rica
  5. Belize
  6. Nicaragua
  7. Honduras

Scientific Name

Thamnophis marcianus is the scientific name of the checkered garter snake. The name marcianus is a reference to General Marcy, a well-known frontier surveyor in the mid-1800s.

It belongs to the Colubridae family and class Reptilia.

The subspecies of this snake include:

Thamnophis marcianus praeocularis
• Thamnophis marcianus bovalli

Population & Conservation Status

The population of the checkered garter snake varies depending on the region. It’s described by the IUCN Red List of Threatened Species as abundant in Texas and rare in Costa Rica. As a consequence, there’s not exact population listed for this garter snake. It’s categorized as Least Concern.

Appearance and Description

A checkered garter snake on rocky soil

Most checkered garter snakes reach a maximum of 18 to 24 inches long.

The ridged scales on the back of this snake are green with a black and white checkered pattern. There is a long white stripe down the middle of its back all the way to the end of its thin tail. The middle stripe is bordered by two more narrow, white stripes. The snake has a green head with black and white vertical stripes around its mouth. It has a white belly with narrow black bars and round eyes with black pupils.

Normally, the snake is 18 to 24 inches long but can be as large as 42 inches.

How to identify a checkered garter snake:

  • Green base scales with a black and white checkered pattern
  • A long white stripe down the middle of its back bordered by two thinner white stripes
  • A slender body with a thin tail
  • A green head with black and white stripes around its mouth
  • A white belly with narrow black bars
  • Round pupils

An albino checkered garter snake is a rare find in nature. The albino variety of this snake has white or yellowish scales and red eyes. Otherwise, it’s the same size sharing the same diet and habits as other garter snakes. It’s albino due to a genetic abnormality.

Diet

Checkered garter snakes are carnivorous and primarily feed on small fish, frogs, toads, salamanders, insects, earthworms, and slugs. They hunt mostly in water or near bodies of water by using their sense of smell to locate prey. In addition to hunting for food in the wild, they will often scavenge for food as well. Checkered garter snakes are excellent swimmers and have been known to travel long distances over land in search of a meal. When not actively hunting, checkered garter snakes can be found basking in the sun or hiding under rocks or logs during the day. At night they become more active and may travel several miles in search of food which makes them an important predator species within aquatic ecosystems.

How Dangerous Are They?

A checkered garter snake lying on a rock

The checkered garter snake is aptly named for the black and white checkered pattern of scales running down its back.

Checkered garter snakes have venom but are not dangerous to humans. Their venom is not like the venom of a copperhead or cobra. A checkered garter snake’s venom is so mild it doesn’t pose a threat to people. Furthermore, this snake has small teeth, so its bite feels a lot like a sting.

Though the checkered garter snake is not poisonous to a human, there is some care necessary to address a bite from this reptile.

If the bite breaks through the skin, wash the area with soap and water. Next, apply first-aid cream to stave off infection. Then, cover the bite marks with a bandage to protect it as the skin heals. If a lot of redness or swelling develops around the bite wound, it needs additional care from a medical professional. Some garter snakes carry bacteria in their mouth, so it’s a good idea to get the bite checked if it doesn’t heal in a timely way.

A checkered garter snake has a secret weapon it uses against threats. It has the ability to expel a stinky liquid from its body as a way to make predators (and humans) retreat! The predator is so surprised and grossed out by the stinky liquid it lets the snake go!

Behavior and Humans

A checkered garter snake raising its head

Checkered garter snakes like to live near water and bask on rocks in the sun.

This snake’s wide variety of habitats increases the chances of an encounter with humans. A person who lives near a field, a wooded area, or even an overgrown empty lot is more likely to see this snake than someone residing in an urban area. The checkered garter snake is timid and inclined to slither away at the first sign of a human.

The checkered garter snake is a small to medium-sized species of reptile that typically inhabits wetland areas. They are relatively active during the day, especially in warmer months, and can be seen basking in the sun or hunting for prey. They feed mainly on small amphibians such as frogs and salamanders but will also eat fish, insects, and even other snakes.

These reptiles are known to be quite territorial by nature and have been observed carrying out ‘combat’ behavior when two males cross paths. This involves pushing each other with their heads before one eventually retreats from the area. It has also been reported that they may occasionally produce loud hissing noises as part of this display of dominance as well.

When it comes to breeding season (spring-summer), checkered garter snakes form large communal mating balls where multiple male individuals compete for access to a single female mate within the group. Males use their tails to entwine around those of potential mates while using body movements such as thrashing back and forth in an attempt to court them successfully. Once successful mating has taken place, females will lay eggs shortly afterward, which hatch after about six weeks incubation period in warm conditions.

Reproduction and Life Cycle

The checkered garter snake reproduces through internal fertilization, where the male snake transfers sperm to the female during mating. The females give birth to live young in late summer or early autumn, usually with clutches of 3-20 snakes. These juvenile snakes are born around 6–8 inches long and will reach adulthood at about 16–24 inches when fully grown. Checkered garter snakes typically live for between 6 and 10 years in the wild but can survive up to 20 years if given proper care in captivity.

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Sources

  1. Kansas Outdoors / Accessed May 3, 2022
  2. IUCN Red List / Accessed May 3, 2022
  3. EOL / Accessed May 3, 2022
  4. Wikipedia / Accessed May 3, 2022
  5. Woof Now What / Accessed May 3, 2022
  6. Embora Pets / Accessed May 3, 2022
Heather Hall

About the Author

Heather Hall

Heather Hall is a writer at A-Z Animals, where her primary focus is on plants and animals. Heather has been writing and editing since 2012 and holds a Bachelor of Science in Horticulture. As a resident of the Pacific Northwest, Heather enjoys hiking, gardening, and trail running through the mountains with her dogs.

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Checkered Garter Snake FAQs (Frequently Asked Questions)

Yes, but their venom is different from the venom of a copperhead. A checkered garter snake’s venom is considered harmless to people whereas the venom of a copperhead can cause muscle and tissue damage in a human.