Thamnophis marcianusCheckered Garter Snake

Geographic Range

Checkered garter snakes (Thamnophis marcianus) are commonly found in the United States, Mexico and some parts of Central America. In the United States, they are found in southwest California, southwestern Arizona and southern New Mexico. An abundance of checkered garter snakes are found on the Gila and Colorado Rivers. In Mexico, they have been found as disjunct populations by the Rio Grande River, Veracruz, Juchitan de Zaragoza, Tabasco and central Yucatan Peninsula. In Central America, they have been found by Tegucigalpa, Honduras; Lake Nicaragua and Managua, Nicaragua; northeast Costa Rica; El Estro, Guatemala and Orange Walk, Belize. (Stafford and Meyer, 2000)


Checkered garter snakes inhabit areas from sea-level to elevations of 2,200 m. They can be found in a variety of habitats from wetlands (e.g. wet, moist tropical forest) to drylands (deserts and dry forest). They are found at or near water sources such as rivers, ponds, springs, irrigation ditches, and lakes. When they are in grasslands they tend to burrow under rocks, logs and in thick vegetation. They can also be found in backyards and gardens. Their populations are moving westward, traveling along irrigation canals. (Chaves, et al., 2013; Degenhardt, et al., 1996; Hamilton and Craig, 2008; Rorabaugh, 2004)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • coastal
  • Range elevation
    0 to 2,200 m
    0.00 to ft

Physical Description

Checkered garter snakes get their common name from the checkered pattern of black and light-grey spots along their bodies. Both females and males have the same pattern. They have a pale-yellow stripes along their spines and their sides, while their ventral sides are cream. Their heads are an olive-green color with a single thick black line on their necks. Their bodies can be grey, brown, olive, tan or albino. They have 21 keeled, dorsal scale rows. Adults average 60 g, but can weigh 31 to 122 g. As adults, they can grow to be 45 to 106 cm in length, but the average adult is 55 cm (including their tails). Tail lengths average 16 cm. The tips of their tongues are black and the rest is a vibrant red. On their heads they have a pale-yellow crescent before their necks. Female checkered garter snakes are bulkier and longer than males that are leaner and shorter. Females are, on average, 82 cm long and weigh 81 g, while males are 51 cm long and weigh 51 g. Checkered garter snakes are 15 to 20 cm (including their tails) upon hatching. Juveniles have the same checkerboard patterns as adults. (Degenhardt, et al., 1996; Nelson and Nelson, 1996; Seigel, et al., 2000; Simon, 1979)

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range mass
    31 to 122 g
    1.09 to 4.30 oz
  • Average mass
    60 g
    2.11 oz
  • Range length
    45 to 106 cm
    17.72 to 41.73 in
  • Average length
    55 cm
    21.65 in


Checkered garter snakes grow indeterminately. They are ovoviviparous, meaning feritlized eggs hatch within the bodies of females, so babies are born live. The average length of checkered garter snakes upon hatching is 12 to 15 cm; by the end of their first year, lengths average 25 cm. On average, they grow 10 to 15 cm a year until they reach maturity; their average growth rate after that is approximately 5 cm per year. (Rossman, et al., 1996)


Checkered garter snakes begin mating in spring - as soon as they emerge from hibernation in late March - through early April. When it is time to mate, females stop eating and groups of males emit strong pheromones so that females can find them. Once a female has mated, their mate goes to find another female to inseminate. Females also have the ability to store the sperm. (Ford and Karges, 1987; Gould, 2002)

Checkered garter snakes are ovoviviparous. They mate from late March through early April. Mating in the north happens in densm where temperatures are warmer; temperatures lower than 10°C can cause them to die or have neurological disorders. In the south, when temperatures are 15 to 30°C, reproduction typically is more successful. When they finish mating, females can either store sperm or fertilize immediately after mating. Their gestation period is normally 80 to 105 days. Females give birth to one clutch ranging from 6 to 35 young between the months of July to September. Ford and Karges (1987) studied checkered garter snakes in south Texas and northeast Mexico, and hypothesized that some females can have two broods per year. Although not directly supported, their anecdotal evidence was their discovery of "fully developed" young in two points in the season: April and September.

Males reach sexual maturity at 1.5 years, while females reach sexual maturity at 2 years. As soon as checkered garter snakes are born, they are independent. At birth, checkered garter snakes weigh an average of 13 g. (Ford and Cobb, 1992; Ford and Karges, 1987; Jackson, et al., 2015)

  • Breeding interval
    Female checkered garter snakes breed once or twice yearly. Male checkered garter snakes breed multiple times in the breeding season.
  • Breeding season
  • Range number of offspring
    6 to 35
  • Range gestation period
    80 to 105 days
  • Average time to independence
    0 minutes
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    1.5 years

Male checkered garter snakes do not have any parental involvement beyond the act of insemination. Female checkered garter snakes carry and protect their young in their bodies until birth. Once checkered garter snakes are born, mothers provide no further parental care. (Jackson, et al., 2015; Parker, 1977; Sparkman, 2009)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female


The longest known lifespan of checkered garter snakes in the wild is 7 years. When they are kept in captivity, the longest known lifespan is 10 years. (Ditmars, 1949; Robert, et al., 2007)

  • Average lifespan
    Status: wild
    7 years
  • Average lifespan
    Status: captivity
    10 years


Checkered garter snakes are mainly active during the day, but in southern habitats they are active at night. They are normally solitary and hibernate in large groups of approximately 100. This grouping helps them maintain a healthy body temperature. Checkered garter snakes hibernate in burrows will even travel to hibernate. Their body temperatures must be maintained at 25-30°C for survival when active and during hibernation. They hibernate from October to March, but sometimes come out to bask on warmer winter days.

When preparing to mate, males and females use pheromones and tactile communication to find each other. Because these snakes are not a group-denning species, their pheromone trails must be followed for great distances sometimes. Ford and O'Bleness (1986) found that checkered garter snakes use a species-specific pheromone trail, and evidence of a male following a trail was shown by increased tongue-flicking. In captivity, checkered garter snakes did not follow the trails of other members of the same genus (Thamnopis). They sometimes chase one another prior to mating. Females cease eating when they are ready to mate. Once gravid, females move less frequently than non-gravid females. (Bell, et al., 2007; Bol, 2000; Ford and Karges, 1987; Ford and O'Bleness, 1986; Hudges, 1985; Parker, 1977; Quinn, et al., 1989)

Home Range

Home ranges have not been published for checkered garter snakes. They do not defend a specific territory. These snakes typically are widely dispersed across suitable habitats and do not congregate at any time of the year. (Bol, 2000; Ford and Karges, 1987)

Communication and Perception

Checkered garter snakes communicate using smell and touch duirng breeding season. They use vibrations to detect prey, other snakes, or other animals around them. They also use vision when close to prey sources. They stick their tongues out to collect pheromones in the air released from animals. Ford and O'Bleness (1986) found that they can distinguish between the pheromone trails of other checkered garter snakes and other species. This suggests that they have a unique, species-specific pheromone.

When they are tracking down other checkered garter snakes, they use their sense of smell to pick up on their pheromones. They use a series of 12 to 49 tongue flicks to detect pheromones in the air. Ford and O'Blenness (1986) found that male checkered garter snakes follow females more than females follow males. (Ford and O'Bleness, 1986; Parker, 1977)

Food Habits

The diet of checkered garter snakes consists of a wide variety of animals including earthworms, mice, fish, lizards, slugs, amphibians and eggs. The types of amphibians they eat include tadpoles, adult frogs, and salamanders. They hunt small prey in irrigation ditches and streams using smell and sight. Seigel et al. (2000) observed that 60% of juvenile checkered garter snakes ate earthworms, while 62% of adults ate tadpoles. When they are kept in captivity, they eat thawed-out mice or other snakes. (Montgomery, 2011; Rorabaugh, 2004; Seigel, et al., 2000)

  • Animal Foods
  • amphibians
  • reptiles
  • fish
  • eggs
  • mollusks
  • terrestrial worms


When checkered garter snakes are in danger, they will head for nearby water sources in which to hide. When handled by aggressors, they release a musky-smelling chemical and bite, leaving behind tiny, superficial bite marks. If they are surprised, they will thrash their bodies side to side to confuse predators. Bird predators include American crows (Corvus brachyrhynchos) and grey hawks (Buteo plagiatus). Mammalian predators include striped skunks (Mephitis mephitis), raccoons (Procyon lotor), red foxes (Vulpes vulpes) and domestic cats (Felis catus). They are also preyed upon by milk snakes (Lampropeltis tringulum). Humans (Homo sapiens) are also a predator to checkered garter snakes; their uniquely-patterned skin is often used to make clothing and accessories. (Jackson, et al., 2015)

Ecosystem Roles

Checkered garter snakes feed on many small animals. Some of these are infected by coccidian (apicomplexan) parasites, such as Eimeria serpenticola. These parasites affect checkered garter snakes that live near water sources in Texas. (McAllister, et al., 1995)

Commensal/Parasitic Species
  • Apicomplexan protist (Eimeria serpenticola)

Economic Importance for Humans: Positive

Checkered garter snakes are bought and sold as pets and used for clothing and purses. They are also used in research studies that are fine-tuning captive artificial insemination; Quinn et al. (1989) successfully bred them in captivity via this method and suggested this method could be feasible for rarer species. (Chaves, et al., 2013; Parker, 1977; Quinn, et al., 1989)

  • Positive Impacts
  • pet trade
  • body parts are source of valuable material
  • research and education

Economic Importance for Humans: Negative

Checkered garter snakes bite people if they are provoked. (Stafford and Meyer, 2000)

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

Checkered garter snakes are listed as a species of "Least Concern" on the IUCN Red List. They have no special status on the U.S. Federal list, CITES, or the State of Michigan list.

Chaves et al. (2013) reported that most checkered garter snake populations across their range are stable, but a few disjunct populations in Mexico could be threatened. Several emerging threats include the overuse of pesticides (which may either eliminate prey species or bioaccumulate in the snakes), loss of amphibian prey in Mexico, and habitat loss.

Some checkered garter snakes already inhabit protected lands (e.g., national parks), and there are captive breeding colonies in Mexico. They also are somewhat common in the pet trade, because they are easy to maintain in captivity and fairly docile. Checkered garter snakes are thought to be increasing their range by following irrigation ditches (correlated with expanding agricultural practices). (Chaves, et al., 2013; Ford and Cobb, 1992; Johnson, et al., 2015; Quinn, et al., 1989; Rossman, et al., 1996)


Brilynn Duke (author), Radford University, Lauren Burroughs (editor), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

  1. active during the day, 2. lasting for one day.

union of egg and spermatozoan


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


marshes are wetland areas often dominated by grasses and reeds.


makes seasonal movements between breeding and wintering grounds


eats mollusks, members of Phylum Mollusca


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night

pet trade

the business of buying and selling animals for people to keep in their homes as pets.


chemicals released into air or water that are detected by and responded to by other animals of the same species


an animal that mainly eats fish


having more than one female as a mate at one time


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.


living in residential areas on the outskirts of large cities or towns.


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


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Chaves, G., W. Lamar, L. Porras, A. Solórzano, J. Sunyer, G. Hammerson. 2013. "Thamnophis marcianus" (On-line). The IUCN Red List of Threatened Species 2013: e.T198521A2529116.. Accessed September 14, 2005 at

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