Sonora semiannulata
(Western Ground Snake)

Key Characteristics

Color variable (may be solid, striped or banded)
Smooth scales
Round pupils
Small size

General Description:
Western Ground Snakes are variable in coloration, occuring with banded, striped or nearly solid dorsal patterns.  The different color forms (morphs) can even be found in the same population (Jonathon M. Beck, pers. com. 1995).  The pattern I have mainly encountered consists of a wide, orange dorsal stripe that is broken by black saddles, forming a banded appearance.  This banded pattern can occur without the reddish-orange dorsal stripe, causing a light and dark banded coloration.  Other color patterns include the reddish-orange dorsal stripe without any black saddles, and nearly solid gray dorsal coloration with only a faint (if any) dorsal stripe.  The reddish-orange banded individuals could possibly be confused with Longnose Snakes.   However, Western Ground Snakes lack the profuse white speckling and the single caudal scales that Longnose Snakes have.  Other morphological features of Western Ground Snakes are smooth scales, round pupils and a slight spine on the tip of the tail (Nussbaum et al. 1983).

Western Ground Snakes are small snakes that only attain maximum lengths of about 38.1 cm (15 in.) (Storm and Leonard 1995).

Little is known about Western Ground Snake reproduction in Idaho (Storm and Leonard 1995).  However, in other parts of their range, they mate during both the spring and the fall, and lay clutches of up to 6 eggs in early June to late August (Behler and King 1979).  Juvenile Western Ground Snakes resemble adults.

Western Ground snakes are found in arid habitats usually having loose or sandy soil (Storm and Leonard 1995), ranging from rocky areas(talus slopes, canyon rims and outcroppings) to low desert shrub areas.  These secretive snakes are seldom encountered, but can occasionally be found by turning debris in the daytime, out in the open near sunset, or on desert roads at night.

Idaho Distribution:
In Idaho, Western Ground Snakes are restricted to the southwestern portion of the state, along the Snake River and surrounding drainages.

Eats spiders, scorpions, centipedes, crickets, grasshoppers and insect larvae.

NocturnalClick word for definition.   HibernatesClick word for definition/aestivatesClick word for definition.  Little is known about ecology or life history in the Northwest.  In northern range, most active on warm nights from April to October.   Active as early as mid-March in west Texas.  Preyed upon by raptors.   Shallow grooves on outer sides of rear teeth suggest species is mildly venomous.

Female lays clutch of 4-6 eggs, usually in June, but as late as August in California.  Adults reach sexual maturity in second year.



Unprotected nongame species

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Important State Reference:
Diller, L. V. and R. L. Wallace. 1981.  Additional distribution and abundance of three species of snakes in southwestern Idaho.  Great Basin Natur. 41:154-15

Design optimization and revision by Ean Harker ©1999, 2000
Original images provided by Charles R. Peterson, Johnathan M. Beck and John Cossel Jr. ©1998
Original work by John Cossel Jr. © 1998