Mexican Garter Snake
Thamnophis eques
A wetland-dependent garter snake of the desert Southwest and Mexico, now rare across much of its northern range.
- Venomous?
- Mildly venomous
- Adult length
- 0.5-1.1 m (1.6-3.6 ft)
- Range
- Southwestern United States (Arizona, New Mexico) south through Mexico
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Overview
The Mexican garter snake is a semi-aquatic species found from the southwestern United States through much of Mexico, historically common along rivers and cienegas but now greatly reduced in Arizona and New Mexico.
Its decline has been linked to habitat loss and the spread of non-native predatory fish and bullfrogs in its aquatic habitats.
How to identify it
- Olive-brown to gray background color
- Distinct yellowish or tan dorsal stripe
- Faint or checkered lateral markings
- Keeled scales
- Head only slightly distinct from neck
- Distinguished from other regional garter snakes by combination of range and dorsal stripe color
Habitat & range
Associated with rivers, cienegas, stock tanks, and wetlands in desert grassland and riparian habitats from Arizona and New Mexico south through the Mexican highlands.
Behavior, diet & reproduction
Semi-aquatic, hunting fish, frogs, and tadpoles in and near water. Active during the day in warmer months. Bears live young. Populations in the United States are considered threatened due to habitat degradation and invasive species.
Frequently asked questions
Why has the Mexican garter snake declined in the U.S.?
Habitat loss and the introduction of non-native fish and bullfrogs that prey on or compete with it have caused significant declines.
Is it venomous?
It has mild venom used to subdue small prey but is not dangerous to humans.
Where is it found?
It occurs in wetlands and rivers from Arizona and New Mexico south through much of Mexico.
What does it eat?
It feeds on fish, frogs, and tadpoles found in and around water.
Mexican Garter Snake guides
In-depth guides for identifying and understanding Mexican Garter Snake.
