Western terrestrial garter snake
|Western terrestrial garter snake|
|T. elegans terrestris|
(Baird & Girard, 1853)
6 sspp., see text
Most western terrestrial garter snakes have a yellow, light orange, or white dorsal stripe, accompanied by two stripes of the same color, one on each side. Some varieties have red or black spots between the dorsal stripe and the side stripes. It is an immensely variable species, and even the most experienced herpetologists have trouble when it comes to identification. They are medium-sized snakes, usually 46–104 cm (18–41 in).
Like many species of North American garter snake, the Western terrestrial garter snake possesses a mildly venomous saliva. Specimens collected from Idaho and Washington produced venom with myonecrotic (muscle tissue-killing) effects when injected into the gastrocnemius muscles of mice. Several cases of mild human envenomation with local edema and other symptoms (but without any systemic symptoms) have occurred from the wandering garter snake subspecies, including in Colorado.
This species is the only garter snake species with a well-documented tendency to constrict prey, although the constriction is inefficient when compared with the constriction of many other snakes (such as the gopher snake), involving disorganized, loose, and sometimes unstable coils and a longer time required to kill prey. Snakes from Colorado populations of terrestrial garter snakes appear to be more efficient at killing their prey by constriction than those from Pacific Coast populations.
Thamnophis elegans is found in southwestern Canada and the western United States, as far east as western Nebraska and the Oklahoma Panhandle. An isolated population occurs in Baja California, Mexico.
Several subspecies or races have been identified, although the validity of some is debated.
- Thamnophis elegans arizonae Tanner and Lowe, 1989 – Arizona Garter Snake
- Thamnophis elegans elegans (Baird and Girard, 1853) – Mountain Garter Snake
- Thamnophis elegans hueyi Van Denburgh and Slevin, 1923 – San-Pedro-Martir Garter Snake
- Thamnophis elegans terrestris Fox, 1951 – Coast Garter Snake
- Thamnophis elegans vagrans (Baird and Girard, 1853) – Wandering Garter Snake
- Thamnophis elegans vascotanneri Tanner and Lowe, 1989 – Upper Basin Garter Snake
Thamnophis elegans occurs in a wide variety of habitats, including grasslands, woodlands, and coniferous forests, from sea level to found of up to 3,962 m (12,999 ft). It is primarily terrestrial, although populations in the Great Basin and Rocky Mountains are semiaquatic.
It will eat just about everything it can find, and is one of only two garter snakes known to cannibalize.
- Thamnophis elegans, The Reptile Database. www.reptile-database.org
- Jansen, David W. (1987). The Myonecrotic Effect of Duvernoy's Gland secretion of the snake Thamnophis elegans vagrans. Journal of Herpetology. 21:81-83/
- Gomez, H.F.; Davis, M.; Phillips, S.; McKinney, P.; and Brent, J. (1984). Human envenomation from a wandering garter snake. Annals of Emergency Medicine. 23:1119–22
- Vest, DK. (1981). Envenomation following the bite of a wandering garter snake (Thamnophis elegans vagrans). Clinical Toxicology. 18:573-9.
- Alan de Queiroz and Rebecca R. Groen. (2001). The inconsistent and inefficient constricting behavior of Colorado Western Terrestrial Garter Snakes, Thamnophis elegans. Journal of Herpetology 35(3):450–460.
- Patrick T. Gregory, J. Malcolm Macartney, and Donald H. Rivard. (1980). Small mammal predation and prey handling behavior by the wandering garter snake Thamnophis elegans. Herpetologica 36(1):87–93.
- Stebbins, Robert C (2003). A field guide to western reptiles and amphibians (3rd ed.). Boston: Houghton Mifflin. p. 377-380. ISBN 0395982723.
- Schmidt, K.P. and D.D. Davis. (1941). Field Book of Snakes of the United States and Canada. G.P. Putnam's Sons. New York. p. 246.