A Guide to the Amphibians
and Reptiles of California

Thamnophis atratus intergrades

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Range in California: Gold

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to the other subspecies.

North of the San Francisco Bay, there is a very large range of intergradation between subspecies of Thamnophis atratus. The snakes in this area were formerly classified as Thamnophis atratus aquaticus (or Thamnophis couchii aquaticus.) This subspecies is no longer recognized.

	Adult, Marin County

Adult, Marin County, left, with sympatric T. e. terrestris on right.	Adult, Solano County

Adult, Marin County	Adult, Marin County
Habitat

Habitat, Marin County	Habitat, Solono County	Habitat, Marin County