Mexican Garter Snake

Fascinating facts about the Mexican Garter Snake

• In north-central Arizona, potential aquatic prey captured during minnow trap surveys included non-native fish such as western mosquitofish and bluegills.
• Ten recognized subspecies are known, and most are restricted to lake basins in Mexico.
• One subspecies, the Lake Chapala garter snake, is endemic to Lake Chapala.
• This snake ranges from deserts and sky-island forests in Arizona and New Mexico to thornscrub and rainforests in Mexico.

At a glance

About the Mexican Garter Snake

The Mexican garter snake (Thamnophis eques) glides through a mosaic of deserts, sky-island forests, thornscrub, and rainforests, its sleek, banded body a flash of amber and black against the varied backdrop of Arizona, New Mexico, and Mexico. Though harmless, this semi-aquatic colubrid is a master of both land and water, slipping into lake basins where ten recognized subspecies have carved out niche habitats, including the Lake Chapala garter snake (T. e. obscurus) found only in the waters of Lake Chapala. Its diet reads like a regional inventory of small vertebrates: lizards, frogs, toads, tadpoles, fish, and opportunistically earthworms, snails, insects, and tiny mammals, making it a true generalist predator. In north-central Arizona, researchers documenting aquatic prey during minnow trap surveys discovered the snake’s opportunistic palate extending to non-native minnows, western mosquitofish, red shiners, green sunfish, bluegills, smallmouth and largemouth bass, yellow and black bullheads, common carp, and even American bullfrog larvae, alongside native Woodhouse’s toads and Sonora mud turtle hatchlings. This surprising willingness to consume both native and introduced species hints at a flexible foraging strategy that may help the snake navigate changing ecosystems, a trait that keeps it thriving across its broad range

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