Variable ground snake (Sonora semiannulata)

The western ground snake (Sonora semiannulata) is a species of small, harmless colubrid snake endemic to North America. It is sometimes referred to as the common ground snake or variable ground snake as its patterning and coloration can vary widely, even within the same geographic region.

Geographic range

It is native to the Southwestern United States, in Arizona, California, Colorado, Kansas, Missouri, New Mexico, Oklahoma, Texas, and Utah, as well as northern Mexico, in Chihuahua, Coahuila, Durango, Nuevo León, and Sonora.


Ground snakes can grow to a total length of 10 to 15 inches (25 to 38 cm). Their colors and patterns can vary widely. They can be brown, red, or orange, with black banding, orange or brown striping, or be solid-colored. The underside is typically white or gray. They have fairly smooth dorsal scales, a small head, and eyes with round pupils.


Their preferred habitat is dry, rocky areas with loose soil.


Ground snakes are typically nocturnal and secretive, but they are common throughout their range. They are often found on roadsides, or in dry drainage ditches at night, foraging for food.


Their diet consists primarily of invertebrates, such as spiders, scorpions, centipedes, crickets, and insect larvae.


They are oviparous, breeding and laying eggs through the summer months.


Sonora semiannulata was once broken up into five separate subspecies, based on the vast differences in color and patterning that the species displays, but recent research has shown that the various colors and patterns of ground snake interbreed indiscriminately, making distinction between them impossible and thus not warranting subspecies status, though some sources still refer to them – using geography as a basis rather than morphology.


Text is available under the Creative Commons Attribution-ShareAlike License. Photograph is available under a Creative Commons License from Jonathan Hakim.

About the author

Jim Mattern

Jim is a scapegoat for the NPS, an author, adventurer, photographer, radio personality, guide, and location scout. His interests lie in Native American and cultural sites, ghost towns, mines, and natural wonders in the American Deserts.

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