The common garter snake (Thamnophis sirtalis) is a species of snake in the subfamily Natricinae of the family Colubridae. The species is indigenous to North America and found widely across the continent. There are several recognized subspecies. Most common garter snakes have a pattern of yellow stripes on a black, brown or green background, and their average total length (including tail) is about , with a maximum total length of about . The average body mass is . The common garter snake is the state reptile of Massachusetts.
Taxonomy and etymology
The subspecific name fitchi is in honor of the American herpetologist Henry Sheldon Fitch.
The subspecific name pickeringii is in honor of the American naturalist Charles E. Pickering.
Subspecies
Current scientific classification recognizes 12 subspecies (ordered by date):
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! Image !! Subspecies !! Distribution
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|120px|| T. s. sirtalis <small>(Linnaeus, 1758)</small> – eastern garter snake ||eastern North America
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|120px|| T. s. parietalis <small>(Say, 1823)</small> – red-sided garter snake||as far north as Fort Smith, Northwest Territories, and as far south as the Oklahoma-Texas border
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|120px||T. s. infernalis <small>(Blainville, 1835)</small> – California red-sided garter snake ||California coast
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|120px||T. s. concinnus <small>(Hallowell, 1852)</small> – red-spotted garter snake ||northwestern Oregon and southwestern Washington
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|| T. s. dorsalis <small>(Baird & Girard, 1853)</small> – New Mexico garter snake ||Mexico and southern New Mexico.
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|120px|| T. s. pickeringii <small>(Baird & Girard, 1853)</small> – Puget Sound garter snake ||Northwestern Washington, Vancouver Island and the southwestern British Columbia
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|120px|| T. s. tetrataenia <small>(Cope, 1875)</small> – San Francisco garter snake (endangered) ||San Mateo County, California
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|120px|| T. s. semifasciatus <small>(Cope, 1892)</small> – Chicago garter snake || Chicago, Illinois
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|120px|| T. s. pallidulus <small>Allen, 1899</small> – maritime garter snake ||northeastern New England, Quebec, and the Maritime provinces.
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|120px|| T. s. annectens <small>B.C. Brown, 1950</small> – Texas garter snake ||Texas, Oklahoma and Kansas
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|120px|| T. s. fitchi <small>Fox, 1951</small> – valley garter snake ||Rocky Mountains and interior ranges
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|120px|| T. s. similis <small>Rossman, 1965</small> – blue-striped garter snake ||northwestern peninsular Florida
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A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than Thamnophis.
Anatomy and description
Common garter snakes are thin snakes. Few grow over about long, and most stay smaller. Most have longitudinal stripes in many different colors. Common garter snakes come in a wide range of colors, including green, blue, yellow, gold, red, orange, brown, and black.
Venom
thumb|upright=1.2|Tetrodotoxin effects in garter snakes
Garter snakes have a mild venom in their saliva, which may be toxic to the amphibians and other small animals that they prey upon. For humans, a bite is not dangerous, and many handlers can attest to garter snakes gently biting in protest when held or restrained; these bites do not often break the skin, given the garter snake's smaller size, but may cause slight itching, burning, and/or swelling at the location of the bite. However, it is more likely that, prior to expending their energy through biting, garter snakes will secrete a foul-smelling fluid ("musk", "musking", "skunking") from postanal glands.
Common garter snakes are resistant to naturally occurring poisons in their prey, such as that of the American toad and rough-skinned newt, the latter of which can kill a human if ingested. Garter snakes (in addition to their own mildly venomous saliva) have the ability to retain poisons from their consumed amphibian prey, thus making them poisonous and deterring any would-be predators. The antipredator display that this species uses demonstrates the idea of an "arms race" between different species and their antipredator displays.
Habitat
The habitat of the common garter snake ranges from forests, fields, and prairies to streams, wetlands, meadows, marshes, and ponds, and it is often found near water. Depending on the subspecies, the common garter snake can be found as far south the southernmost tip of Florida in the United States and as far north as the southernmost tip of the Northwest Territories in Canada. It is found at altitudes from sea level to mountains.
Behavior and life history
The common garter snake is a diurnal snake. In summer, it is most active in the morning and late afternoon; in cooler seasons or climates, it restricts its activity to the warm afternoons.
In warmer southern areas, the snake is active year-round; otherwise, it sleeps in common dens, sometimes in great numbers. On warm winter afternoons, some snakes have been observed emerging from their hibernacula to bask in the sun.
Antipredatory displays
Garter snakes exhibit many different behaviors to ward off predators. Garter snakes exhibit a greater variety of body postures than other snakes. Under selection by predation, these snakes have developed postural responses that are highly variable and heritable. These are highly variable even within a single population. After such a male has led rivals away, he "turns" back into a male and races back to the den, just as the females emerge. He is then the first to mate with all the females he can catch. This method also serves to help warm males by tricking other males into surrounding and heating up the male, and is particularly useful to subspecies in colder climates (such as those inhabited by T. s. parietalis); this type of mimicry is primarily found in that subspecies. fish, lizards, other snakes,
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Bibliography
Further reading
- Conant, Roger; Bridges, William (1939). What Snake Is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains. (with 108 drawings by Edmond Malnate). New York and London: D. Appleton Century Company. Frontispiece map + viii + 163 pp. + Plates A-C, 1-32. (Thamnophis sirtalis, pp. 124–126 + Plate 24, figures 70–72).
- Linnaeus C (1758). Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio Decima, Reformata. Stockholm: L. Salvius. 824 pp. (Coluber sirtalis, new species, p. 222). (in Latin).
- Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp., 47 plates, 207 figures. . (Thamnophis sirtalis, pp. 431–433 + Plate 43).
- Schmidt, Karl P.; Davis, D. Dwight (1941). Field Book of Snakes of the United States and Canada. New York: G.P. Putnam's Sons. 365 pp., 34 plates, 103 figures. (Thamnophis sirtalis, pp. 252–255 + Plate 26).
- Smith HM, Brodie ED Jr (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. . (Thamnophis sirtalis, pp. 148–149).
- Stebbins RC (2003). A Field Guide to Western Reptiles and Amphibians, Third Edition. The Peterson Field Guide Series . Boston and New York: Houghton Mifflin. xiii + 533 pp., 56 plates. . (Thamnophis sirtalis, pp. 375–377 + Plate 48 + Map 162).
- Wright, Albert Hazen; Wright, Anna Allen (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. 1,105 pp. (in 2 volumes). (Thamnophis sirtalis, pp. 834–863, Figures 242–248, Map 60).
External links
- Care of Garter Snakes
- Garter Snake Information
- Caring for Your Garter Snake
.
- Eastern Garter Snake at Ontario Nature.
- Red-sided Garter Snake at Ontario Nature.