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Thamnophis atratus

(Kennicott, 1860)

Aquatic Gartersnake

G5Secure Found in 59 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
LowThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.100361
Element CodeARADB36140
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicendemic to a single nation
KingdomAnimalia
PhylumCraniata
ClassReptilia
OrderSquamata
FamilyColubridae
GenusThamnophis
Synonyms
Thamnophis couchii atratus(Kennicott)
Other Common Names
Aquatic Garter Snake (EN) Pacific Coast Aquatic Garter Snake (EN) Santa Cruz Garter Snake (EN)
Concept Reference
Rossman, D. A., N. B. Ford, and R. A. Seigel. 1996. The garter snakes: evolution and ecology. University of Oklahoma Press, Norman. xx + 332 pp.
Taxonomic Comments
Rossman and Stewart (1987) recognized Thamnophis atratus and T. couchii as distinct species. They recommended that T. a. aquaticus not be recognized as a valid taxon (atratus, hydrophilus, and aquaticus formerly were recognized as subspecies of T. couchii). Rossman et al. (1996) and Boundy (1999) also did not recognize aquaticus as valid.
Conservation Status
Review Date2006-09-05
Change Date1996-10-30
Edition Date2006-09-05
Edition AuthorsHammerson, G.
Threat ImpactLow
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences81 - 300
Range Extent Comments
The range includes southwestern Oregon and western California north of Pt. Concepcion, at elevations from sea level to around 1,920 meters (Nussbaum et al. 1983, Brown et al. 1995, Rossman et al. 1996, Stebbins 2003).
Occurrences Comments
This species is represented by a large number of occurrences (subpopulations).
Threat Impact Comments
No major threats are known. Predation by introduced bullfrogs may be a concern in some areas.
Ecology & Habitat

Habitat

Habitats include rocky fast-flowing streams, sluggish streams with soft bottoms, ponds, small lakes, and the adjacent riparian zone, in areas surrounded by woodlands, woodland-grass ecotones, or chaparral (Nussbaum et al. 1983, Rossman et al. 1996, Ernst and Ernst 2003, Stebbins 2003). This snake basks on boulders and vegetation along banks and in mid-stream; it seeks cover under water under rocks or among exposed tree roots. In most areas this snake is closely tied to water, but individuals sometimes travel on land away from water.

Reproduction

Mates in spring; young are born August-October (Nussbaum et al. 1983, Brown et al. 1995).
Palustrine Habitats
HERBACEOUS WETLANDRiparian
Other Nations (2)
United StatesN5
ProvinceRankNative
OregonS4Yes
CaliforniaSNRYes
CanadaNNR
ProvinceRankNative
British ColumbiaSNRYes
Threat Assessments
ThreatScopeSeverityTiming
8 - Invasive & other problematic species, genes & diseases——Moderate - low
8.1 - Invasive non-native/alien species/diseases——Moderate - low

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Roadless Areas (59)
California (55)
AreaForestAcres
BackboneShasta-Trinity National Forest11,466
Bell QuinbyShasta-Trinity National Forest11,556
Big Butte ShinboneMendocino National Forest4,265
BlackKlamath National Forest6,530
Black ButteMendocino National Forest15,461
Bonanza KingShasta-Trinity National Forest16,402
Castle Crags AShasta-Trinity National Forest113
Castle Crags BShasta-Trinity National Forest1,619
Chalk PeakLos Padres National Forest7,472
ChanchelullaShasta-Trinity National Forest3,915
ChinquapinShasta-Trinity National Forest22,040
Cow CreekSix Rivers National Forest1,271
Cow CreekShasta-Trinity National Forest22,627
Devils RockShasta-Trinity National Forest16,209
Dog CreekShasta-Trinity National Forest5,001
East ForkShasta-Trinity National Forest6,201
East GirardShasta-Trinity National Forest27,894
Elk CreekMendocino National Forest23,182
Garcia MountainLos Padres National Forest7,850
GrindstoneMendocino National Forest26,031
JohnsonKlamath National Forest10,652
KangarooKlamath National Forest40,617
KellySix Rivers National Forest5,195
Lake EleanorShasta-Trinity National Forest397
Little French CShasta-Trinity National Forest11,529
Mt. EddyShasta-Trinity National Forest7,232
Mt. LassicSix Rivers National Forest6,643
MuseKlamath National Forest238
North Fork SmithSix Rivers National Forest37,898
Orleans Mtn.Klamath National Forest49,090
Orleans Mtn. BSix Rivers National Forest17,183
Orleans Mtn. CSix Rivers National Forest15,589
PacksaddleSix Rivers National Forest3,862
PantherShasta-Trinity National Forest12,016
PattisonShasta-Trinity National Forest29,299
Penney RidgeShasta-Trinity National Forest5,226
Pilot CreekSix Rivers National Forest9,192
PortugueseKlamath National Forest18,915
RussianKlamath National Forest21,771
Salt GulchShasta-Trinity National Forest6,511
ShacklefordKlamath National Forest1,679
SiskiyouKlamath National Forest54,039
Siskiyou BSix Rivers National Forest18,871
Skeleton GladeMendocino National Forest9,237
SnoozerKlamath National Forest23,414
Snow MountainMendocino National Forest14,457
SoliderSix Rivers National Forest14,918
South ForkShasta-Trinity National Forest16,786
Thomes CreekMendocino National Forest16,616
Tom MartinKlamath National Forest9,031
UnderwoodSix Rivers National Forest6,591
UnderwoodShasta-Trinity National Forest3,046
Weaver BallyShasta-Trinity National Forest829
West GirardShasta-Trinity National Forest37,516
Wilderness ContiguousMendocino National Forest3,606
Oregon (4)
AreaForestAcres
Castle Rock AppendageUmpqua National Forest4,649
North KalmiopsisSiskiyou National Forests91,560
Shasta CostaSiskiyou National Forests14,420
South KalmiopsisSiskiyou National Forests104,477
References (11)
  1. Boundy, J. 1999. Systematics of the garter snake <i>Thamnophis atratus</i> at the southern end of its range. Proceedings of the California Academy of Science 51 (6): 311-336.
  2. Brown, H. A., R. B. Bury, D. M. Darda, L. V. Diller, C. R. Peterson, and R. M. Storm. 1995. Reptiles of Washington and Oregon. Seattle Audubon Society, Seattle, Washington. viii + 176 pp.
  3. Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
  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. Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho, Moscow, Idaho. 332 pp.
  8. Rossman, D. A., and G. R. Stewart. 1987. Taxonomic reevaluation of <i>Thamnophis couchii</i> (Serpentes: Colubridae). Occasional Papers of the Museum of Zoology Louisiana State University (63):1-25.
  9. Rossman, D. A., N. B. Ford, and R. A. Seigel. 1996. The garter snakes: evolution and ecology. University of Oklahoma Press, Norman. xx + 332 pp.
  10. Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
  11. Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.