Checkered Garter Snake
Thamnophis marcianus • Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. marcianus
Found in southwestern United States (including Texas, New Mexico, Arizona, Oklahoma) and northern Mexico, extending down through Central America.
Look up Checkered Garter Snake in the Snake Encyclopedia →Family
Order: Squamata, Suborder: Serpentes, Family: Colubridae, Subfamily: Natricinae, Genus: Thamnophis, Species: T. marcianus
Conservation
IUCN Red List status is Least Concern, with stable populations across most of its natural range, though local populations face threats from habitat loss and water diversion.
Physical Description
Features a prominent checkered or blotched dorsal pattern of dark brown or black squares on an olive, gray, or tan background. A distinct light dorsal stripe runs down the back alongside lateral stripes. The head has distinct light vertical bars on the labial scales and a characteristic pale parietal spot.
Size & Dimensions
The pictured specimen appears to be a juvenile measuring approximately 12 to 15 inches. Adults typically range from 18 to 36 inches in total length.
Habitat
Inhabits arid and semi-arid regions, typically near permanent or temporary water sources such as streams, ponds, irrigation ditches, and floodplains, spanning from lowlands up to moderate elevations.
Diet & Feeding
Feeds primarily on amphibians (such as frogs and toads), small fish, and occasionally earthworms, using an active foraging strategy near water bodies.
Reproduction
Viviparous (live-bearing), producing litters typically ranging from 5 to 20 or more young during the summer months after a spring mating season.
Look-alikes
Frequently confused with other garter snake species (Thamnophis species) and patch-nosed snakes (Salvadora species). Distinguished by the prominent checkered pattern and the distinct pale spots on the parietal scales of the head.
Conservation Status
IUCN Red List status is Least Concern, with stable populations across most of its natural range, though local populations face threats from habitat loss and water diversion.
Cultural Significance
Acts as an important mid-level predator in wetland and riparian ecosystems, helping control amphibian and invertebrate populations.
Notable Features
Exhibits specialized labial scale markings and a remarkably bold checkered pattern that provides disruptive camouflage among rocky substrate near water.