BC Conservation Data Centre: Species Summary
Thamnophis sirtalis
Common Gartersnake
| Scientific Name: | Thamnophis sirtalis (Linnaeus, 1766) | ||||||||||
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| English Name: | Common Gartersnake | ||||||||||
| English Name Synonyms: |
Common Garter Snake
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| Classification / Taxonomy | |||||||||||
| Scientific Name - 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. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Vertebrate Animal | ||||||||||
| Species Code: | R-THSI | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G5 (Feb 2016) | ||||||||||
| Provincial Status: | S5 (Mar 2018) | ||||||||||
| BC List: | Yellow | ||||||||||
| Provincial FRPA list: | |||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | |||||||||||
| SARA Schedule: | |||||||||||
| General Status Canada: | 4 - Secure (2005) | ||||||||||
| Ecology & Life History | |||||||||||
| General Description: | The coloration varies geographically and is difficult to characterize succinctly. These snakes have 19 dorsal scale rows at mid-body, a pale lateral stripe on each side on the 2nd and 3rd scale rows (also on row 4 in subspecies annectans of Texas-Oklahoma), 7 scales on each upper lip, 1 preocular (scale in front of eye), 3 postoculars (scales behind eye), keeled scales on the back, and an undivided anal scale (covers vent). Adult total length is usually 16-26 inches (41-66 cm), with the maximum around 52 inches) (131 cm). Newborns are around 5-7 inches (12-23 cm) in total length (Conant and Collins 1991, Smith and Brodie 1982). | ||||||||||
| Global Reproduction Comments: | In much of the range, mating occurs primarily in spring, just after emergence from hibernation, though possibly to a limited extent also in late summer. Adult females give birth usually in July or August but earlier in the south and as late as early October in the north. Litter size averages about 13-26 but varies geographically (generally larger in the east than in the west); the largest females tend to produce the largest litters. Individuals become sexually mature in 1-2 years. In Northwest Territories, Canada, females evidently rarely gave birth in successive years (Larsen et al. 1993). See Cover and Boyer (1988) for information on captive breeding. | ||||||||||
| Global Ecology Comments: | Home range size variously reported as 0.8 ha to 14 ha (DeGraaf and Rudis 1983). In the far northern part of the range, thousands may aggregate at hibernacula. Population density estimates in different areas range from about 10/ha to 100/ha. | ||||||||||
| Migration Characteristics: (Global / Provincial) | |||||||||||
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Nonmigrant: Local Migrant: Distant Migrant: Within Borders Migrant: |
N / Y / N / na / |
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| Global Migration Comments: | In some areas in the northern part of the range, common gartersnakes make long migrations between winter hibernacula and summer range (up to at least 16 km between winter hibernaculum and summer range in at least some northern localities; Fitch 1980). In Manitoba, females dispersed from a communal den in all directions, rather than following distinct migration corridors (Shine et al. 2001). | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
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| Global Habitat Comments: |
Throughout the range, common gartersnakes inhabit a very wide range of aquatic, wetland, and upland habitats; habitat preference exhibits rather pronounced regional differences (e.g., east vs. west). In some regions, such as much of eastern North America, these snakes are decidedly terrestrial and range far from water. In other areas, such as the Rocky Mountain region, they are mostly confined to riparian corridors. When inactive, they occur underground, in or under surface cover, or in other secluded sites. In some areas, common gartersnakes spend the cold winter months completely submerged in water. Submerged snakes retain more body water and conserve more stored energy than do snakes in dry sites. At the low temperatures of hibernation, the snake's metabolic rate is very low, so oxygen needs can be met even while the snake is submerged and unable to breathe air. |
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| Food Habits: |
Carnivore: Adult, Immature
Invertivore: Adult, Immature Piscivore: Adult, Immature |
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| Global Food Habits Comments: | Preys chiefly on earthworms, frogs, toads, salamanders, and fishes; less regularly on slugs, leeches, small mammals and birds; rarely on insects, spiders, and small snakes (Fitch 1980). | ||||||||||
| Global Phenology: |
Circadian: Adult, Immature
Hibernates/aestivates: Adult, Immature |
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| Global Phenology Comments: | Most activity occurs from about March or April through October in the north and at higher elevations; the active season is longer in the south (year-around in Florida). Common gartersnakes are active both day and night in most of the range; nocturnal activity often occurs during hot weather. |
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| Provincial Phenology: (1st half of month/ 2nd half of month) |
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| Colonial Breeder: | N | ||||||||||
| Length(cm)/width(cm)/Weight(g): | 66/ / | ||||||||||
| Elevation (m) (min / max): |
Global:
Provincial: |
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| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | The wide range includes much of North America, from southeastern Alaska, British Columbia, southern Northwest Territories, northern Saskatchewan, central Manitoba, Ontario, central Quebec, and the Maritime Provinces to southern California, central Utah, northeastern Colorado, New Mexico and Chihuahua (disjunct), Texas, Gulf Coast, and southern Florida (Conant and Collins 1991, Ernst and Ernst 2003, Stebbins 2003). | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | Hammerson, G. | ||||||||||
| Last Updated: | Jan 28, 2010 | ||||||||||
| Provincial Information Author: | |||||||||||
| Last Updated: | |||||||||||
| References and Related Literature | |||||||||||
Barry, S. J., M. R. Jennings, and H. M. Smith. 1996. Current subspecific names for western Thamnophis sirtalis. Herpetological Review 27:172-173. |
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Boundy, J., and D. A. Rossman. 1995. Allocation and status of the garter snake names Coluber infernalis Blainville, Eutaenia sirtalis tetrataenia Cope, and Eutaenia imperialis Coues and Yarrow. Copeia 1995:236-240. |
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Collins, J. T. 1982. Amphibians and reptiles in Kansas. Second edition. Univ. Kansas Mus. Nat. Hist., Pub. Ed. Ser. 8. xiii + 356 pp. |
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Collins, J. T. 1991. Viewpoint: a new taxonomic arrangement for some North American amphibians and reptiles. SSAR Herpetol. Review 22:42-43. |
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Conant, R. and J. T. Collins. 1991. A field guide to reptiles and amphibians: eastern and central North America. Third edition. Houghton Mifflin Co., Boston, Massachusetts. 450 pp. |
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Cover, J. F., Jr., and D. M. Boyer. 1988. Captive reproduction of the San Francisco garter snake Thamnophis sirtalis tetrataenia. Herpetol. Rev. 19:29-30, 32-33. |
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DeGraaf, R. M., and D. D. Rudis. 1983a. Amphibians and reptiles of New England. Habitats and natural history. Univ. Massachusetts Press. vii + 83 pp. |
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Dowling, H. G. 1993. Viewpoint: a reply to Collins (1991, 1992). Herpetol. Rev. 24:11-13. |
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Fitch, H. S. 1970. Reproductive cycles of lizards and snakes. Univ. Kansas Museum Natural History Miscellaneous Publication 52:1-247. |
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Fitch, H. S. 1980. Thamnophis sirtalis. Cat. Am. Amph. Rep. 270.1-270.4. |
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Fitch, H.S. 1965. An ecological study of the garter snake, Thamnophis sirtalis. Univ. Kansas Publ. Mus. Nat. Hist. 15 (10):493-564. |
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Hammerson, G. A. 1982b. Amphibians and reptiles in Colorado. Colorado Division of Wildlife, Denver. vii + 131 pp. |
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Larsen, K. W., P. T. Gregory, and R. Antoniak. 1993. Reproductive ecology of the common garter snake Thamnophis sirtalis at the northern limit of its range. Am. Midl. Nat. 129:336-345. |
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Lawson, R. 1987. Molecular studies of thamnophiine snakes: 1. The phylogeny of the genus Nerodia. J. Herpetology 21:140-157. |
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Minton, S. A., Jr. 1972. Amphibians and reptiles of Indiana. Indiana Academy Science Monographs 3. v + 346 pp. |
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Ovaska, K, S. Lennart, C Engelstoft, L. Matthias, E. Wind and J. MacGarvie. 2004. Best Management Practices for Amphibians and Reptiles in Urban and Rural Environments in British Columbia. Ministry of Water Land and Air Protection, Ecosystems Standards and Planning, Biodiversity Branch |
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Ovaska, K., and C. Engelstoft. 2003. Attracting Snakes into your Backyard - tips for reptile-friendly landscaping and gardening. Can. Habitat Stewardship Program, Habitat Conservation Trust Fund, and B.C. Minist. Water, Land and Air Prot. 4pp. |
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Shine, R, M. J. Elphrick, P. S. Harlow, I. T. Moore, M. P. LeMaster, and R. T. Mason. 2001. Movements, mating, and dispersal of red-sided gartersnakes (Thamnophis sirtalis parietalis) from a communal den in Manitoba. Copeia 2001:82-91. |
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Smith, H. M. and E. D. Brodie, Jr. 1982. Reptiles of North America. Golden Press, New York. 240 pp. |
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The Reptiles of British Columbia: Common Garter Snake, Thamnophis sirtalis. 2004. Univ. Coll. Cariboo, and B.C. Minist. Water, Land and Air Prot. Online. Available: http://www.bcreptiles.ca/snakes/comGarter.htm |
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Vogt, R. C. 1981c. Natural history of amphibians and reptiles of Wisconsin. Milwaukee Public Museum. 205 pp. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. 2010. Species Summary: Thamnophis sirtalis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Mar 9, 2025).