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.

Habitat: The preferred habitats of T. marcianus are desert and grassland, usually close to water.

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.

Found in these States: AZ | CA | KS | NM | OK | TX

Diet: The diet of T. marcianus includes small frogs, toads, small fish, and earthworms. If kept as a pet, it can be trained on live or freeze-thawed mice, but even so, it is a fussy eater and can suddenly start to refuse mice at any point.

Reproduction: 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.

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 degrees celcius, 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.

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.

Status: Listed as Least Concern because the species is widely distributed and relatively common in the northern part of the range. In southern Mexico and Central America, however, the species is less common, and the distribution is fragmented/disjunct.

Subspecies:One, and it is found in the United States:
   Marcy's Checkered Garter Snake - (Thamnophis marcianus marcianus)

Taxonomy: