Western ground snake

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Western ground snake
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Sonora
Species: S. semiannulata
Binomial name
Sonora semiannulata
Baird and Girard, 1853
  • Sonora semiannulata
    Baird and Girard, 1853
  • Lamprosoma episcopum
    Kennicott in Baird, 1859
  • Homalosoma episcopum
    Jan, 1865
  • Contia isozona
    Cope, 1866
  • Contia episcopa isozona
    — Cope,1880
  • Contia taylori
    Boulenger, 1894
  • Chionactis episcopus isozonus
    — Cope, 1900
  • Sonora miniata linearis
    Stickel, 1938
  • Sonora semiannulata
    Liner, 1994

The western ground snake (Sonora semiannulata) is a species of small, harmless colubrid snake. The species is 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.[3]

Geographic range[edit]

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


The western ground snake can grow to a total length (including tail) of 10 to 15 inches (25 to 38 cm). The color and pattern can vary widely. Individuals can be brown, red, or orange, with black banding, orange or brown striping, or be solid-colored. The underside is typically white or gray. It has smooth dorsal scales, a small head, and the pupil of the eye is round.


The preferred habitat of S. semiannulata is dry, rocky areas with loose soil.


The western ground snakes is typically nocturnal and secretive, but it is common throughout its range. It is often found on roadsides, or in dry drainage ditches at night, foraging for food.


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


The western ground snake is 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.


  1. ^ "Sonora semiannulata ". The Reptile Database. www.reptile-database.org.
  2. ^ Stejneger, L., and T. Barbour. 1917. A Check List of North American Amphibians and Reptiles. Harvard University Press. Cambridge, Massachusetts. 125 pp. (Sonora, p. 92.)
  3. ^ Stebbins, R.C. 2003. A Field Guide to Western Reptiles and Amphibians, Third Edition. The Peterson Field Guides Series ®. Houghton Mifflin. Boston and New York. xiii + 533 pp. ISBN 0-395-98272-3. (Sonora semiannulata, pp. 391–393 + Plate 45 + Map 170).

External links[edit]

Further reading[edit]

  • Baird, S.F., and C.F. Girard. 1853. Catalogue of the Reptiles in the Museum of the Smithsonian Institution. Part. I.—Serpents. Smithsonian Institution. Washington, District of Columbia. xvi + 172 pp. (Sonora semiannulata, p. 117.)
  • Smith, H.M., and E.D. Brodie, Jr. 1982. Reptiles of North America: A Guide to Field Identification. Golden Press. New York. 240 pp. ISBN 0-307-13666-3 (paperback). (Sonora semiannulata, pp. 168–169.)
  • Wright, A.H., and A.A. Wright. 1957. Handbook of Snakes of the United States and Canada. Comstock. Ithaca and London. 1,105 pp. (in 2 volumes) (Separate accounts of the following synonyms of Sonora semiannulata: Sonora episcopa episcopa, Sonora episcopa taylori, Sonora semiannulata semiannulata, Sonora semiannulata blanchardi, Sonora semiannulata gloydi, Sonora semiannulata isozona, Sonora semiannulata linearis, pp. 670–692, Figures 196-203 + Map 51 on p. 668.)