Reptiles
Two-Striped Garter Snake
Thamnophis hammondii · also called two-striped garter snakes
Along a shrinking southern California stream, a two-striped garter snake slips beneath the surface after a tadpole, sharing the same increasingly scarce water with several other native species facing the exact same combination of drought and habitat loss.
Overview
The two-striped garter snake, Thamnophis hammondii, is a highly aquatic snake native to stream and wetland habitat across coastal and inland southern California and northern Baja California, Mexico. Its close dependence on permanent water and vulnerability to the same pressures affecting other native stream species make it one of the more conservation-significant reptiles in the region.
A snake caught in a shrinking water supply
As southern California’s streams face increasing pressure from drought and water diversion, the two-striped garter snake finds itself competing for the same dwindling resource that numerous other native species depend on just as urgently.
Status
Vulnerable — declining in parts of southern California, linked to drought, water diversion, habitat loss, and invasive predators.
Two-Striped Garter Snake: common questions
Why is it called the two-striped garter snake?
A two-striped garter snake typically lacks the middle dorsal stripe common to most other garter snake species, displaying only two lateral stripes running down its sides rather than the usual three-stripe pattern, a difference that gave the species its descriptive common name.
Why has the two-striped garter snake declined in parts of its range?
The two-striped garter snake has declined alongside other native stream-dependent species in parts of southern California, a decline linked to drought, water diversion for human use, habitat loss from development, and the spread of invasive predators such as bullfrogs and non-native fish that both prey on the snake and consume the native amphibians it depends on for food.
How closely tied to water is the two-striped garter snake?
The two-striped garter snake is closely associated with permanent or semi-permanent streams and pools, rarely found far from reliable water, and it is a capable swimmer, often diving underwater to escape a threat or pursue aquatic prey such as fish and tadpoles.
Where does the two-striped garter snake live?
The two-striped garter snake is native to stream and wetland habitat across coastal and inland southern California and northern Baja California, Mexico, generally remaining close to permanent water sources.