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Sonora semiannulata

Baird and Girard, 1853

Variable Groundsnake

G4Apparently Secure (G4G5) Found in 20 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
Medium - lowThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.768307
Element CodeARADB32011
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassReptilia
OrderSquamata
FamilyColubridae
GenusSonora
Synonyms
Sonora semiannulata semiannulataBaird and Girard, 1853
Concept Reference
Crother, B. I., J. Boundy, J. A. Campbell, K. de Quieroz, D. Frost, D. M. Green, R. Highton, J. B. Iverson, R. W. McDiarmid, P. A. Meylan, T. W. Reeder, M. E. Seidel, J. W. Sites, Jr., S. G. Tilley, and D. B. Wake. 2003. Scientific and standard English names of amphibians and reptiles of North America north of Mexico: update. Herpetological Review 34:198-203.
Taxonomic Comments
Sonora semiannulata has been split into S. semiannulata, S. episcopa, S. taylori, and S. mosaueri by Cox et al. (2018).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-04-30
Change Date2025-04-30
Edition Date2025-04-30
Edition AuthorsGundy, R. L. (2025)
Threat ImpactMedium - low
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences81 - 300
Rank Reasons
This species is widespread in the southwestern United States and northern México where it is considered common and the population presumed to be stable.
Range Extent Comments
This species is found in the southwestern United States and northern México. The range in the U.S. includes southeastern Oregon, southwestern Idaho, eastern California, western Nevada, southwestern Utah, western and southern Arizona, southwestern New Mexico, and extreme western Texas. The range in México includes northeastern Baja California Norte, northern Sonora, and northern Chihuahua (Cox et al. 2018). Using Global Biodiversity Information Facility (GBIF) (2025) records from the accepted range in Cox et al. (2018), range extent is estimated to be 1,187,764 km² (RARECAT 2025).
Occurrences Comments
There are many occurrences throughout the range (Frost 1983, Cox et al. 2018, GBIF 2025).
Threat Impact Comments
Development and agriculture have reduced the amount of suitable habitat within the range (Bradley and Rosen 2020). Drastic increases in road traffic has likely increased mortality in this species as it has in other desert snakes (Jones et al. 2011).
Ecology & Habitat

Habitat

Habitats include arid and semiarid regions: river bottoms, desert flats, sand hummocks, rocky hillsides with pockets of loose soil; from prairie and desert lowlands to pinyon-juniper and oak-pine zone; soil may be rocky to sandy, vegetation dense to sparse (Tennant 1984, Degenhardt et al. 1996, Stebbins 2003).

Reproduction

Lays clutch of 3-6 eggs (Goldberg 2001), usually in June-July but as late as August (California); sexually mature in 2nd year (Fitch 1970).
Terrestrial Habitats
Woodland - HardwoodWoodland - ConiferWoodland - MixedShrubland/chaparralGrassland/herbaceousDesertSand/dune
Palustrine Habitats
Riparian
Other Nations (1)
United StatesN5
ProvinceRankNative
IdahoS3Yes
NevadaS5Yes
UtahS3Yes
New MexicoSNRYes
CaliforniaSNRYes
ArizonaS5Yes
TexasSNRYes
OregonS3Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentSmall (1-10%)Serious - moderateHigh (continuing)
1.1 - Housing & urban areasSmall (1-10%)Serious - moderateHigh (continuing)
1.2 - Commercial & industrial areasSmall (1-10%)Serious - moderateHigh (continuing)
2 - Agriculture & aquacultureRestricted - smallSerious - moderateHigh (continuing)
2.1 - Annual & perennial non-timber cropsRestricted - smallSerious - moderateHigh (continuing)
4 - Transportation & service corridorsSmall (1-10%)Slight or 1-10% pop. declineHigh (continuing)
4.1 - Roads & railroadsSmall (1-10%)Slight or 1-10% pop. declineHigh (continuing)

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Roadless Areas (20)
Arizona (8)
AreaForestAcres
Black CrossTonto National Forest5,966
BoulderTonto National Forest40,359
GoldfieldTonto National Forest15,257
HackberryCoconino National Forest17,885
HackberryPrescott National Forest914
Horse MesaTonto National Forest9,146
Lime CreekTonto National Forest42,568
MazatzalTonto National Forest16,942
California (4)
AreaForestAcres
Birch CreekInyo National Forest28,816
Black CanyonInyo National Forest32,421
Granite PeakSan Bernardino National Forest450
Soldier CanyonInyo National Forest40,589
Nevada (3)
AreaForestAcres
Boundary Peak (NV)Inyo National Forest21,851
Charleston - Macks CynHumboldt-Toiyabe National Forest11,378
Paradise PeakHumboldt-Toiyabe National Forest18,717
New Mexico (2)
AreaForestAcres
Peloncillo (NM)Coronado National Forest43,339
Ryan HillCibola National Forest34,201
Utah (3)
AreaForestAcres
Bull ValleyDixie National Forest10,911
CottonwoodDixie National Forest6,754
Pine Valley MountainsDixie National Forest57,673
References (19)
  1. Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.
  2. Bradley, C. M., and P. C. Rosen. 2020. Defining suitable habitat and conservation status for the Tucson shovel-nosed snake (<i>Chionactis annulata klauberi</i>) in the Sonoran Desert.
  3. Cox, C. L. A. R. Davis Rabosky, I. A. Holmes, J. Reyes-Velasco, C. E. Roelke, E. N. Smith, O. Flores-Villela, J. A. McGuire, and J. A. Campbell. 2018. Synopsis and taxonomic revision of three genera in the snake tribe Sonorini. Journal of Natural History 52:945-988.
  4. Crother, B. I. (editor). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84. Online with updates at: http://www.ssarherps.org/pages/comm_names/Index.php
  5. Crother, B. I. (editor). 2012. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 7th edition. SSAR Herpetological Circular 39:1-92.
  6. Crother, B. I. (editor). 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 8th edition. SSAR Herpetological Circular 43:1-104. [Updates in SSAR North American Species Names Database at: https://ssarherps.org/cndb]
  7. Crother, B. I., J. Boundy, J. A. Campbell, K. de Quieroz, D. Frost, D. M. Green, R. Highton, J. B. Iverson, R. W. McDiarmid, P. A. Meylan, T. W. Reeder, M. E. Seidel, J. W. Sites, Jr., S. G. Tilley, and D. B. Wake. 2003. Scientific and standard English names of amphibians and reptiles of North America north of Mexico: update. Herpetological Review 34:198-203.
  8. Ernst, C. H., and E. M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Books, Washington, D.C.
  9. Fitch, H. S. 1970. Reproductive cycles of lizards and snakes. Univ. Kansas Museum Natural History Miscellaneous Publication 52:1-247.
  10. Frost, D. R. 1983. <i>Sonora semiannulata</i>. Catalogue of American Amphibians and Reptiles 333.1-333.4.
  11. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  12. Goldberg, S. R. 2001. Reproduction in the ground snake, <i>Sonora semiannulata</i> (Serpentes: Colubridae), from Arizona. Southwestern Naturalist 46:387-391.
  13. Grismer, L. L. 2002. Amphibians and reptiles of Baja California including its Pacific islands and islands in the Sea of Cortes. University of California Press, Berkeley. xiii + 399 pp.
  14. Hammerson, G. A. 1982b. Amphibians and reptiles in Colorado. Colorado Division of Wildlife, Denver. vii + 131 pp.
  15. Jones, T. R., R. D. Babb, F. R. Hensley, C. Liwanpo, and B. K. Sullivan. 2011. Sonoran Desert snake communities at two sites: concordance and effects of increased road traffic. Herpetological Conservation and Biology 6(1): 61-71.
  16. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  17. Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
  18. Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.
  19. Tennant, A. 1984. The Snakes of Texas. Texas Monthly Press, Austin, Texas. 561 pp.