About Thamnophis elegans (Baird & Girard, 1853)
The western terrestrial garter snake, Thamnophis elegans, most often has a yellow, light orange, or white dorsal stripe, plus two additional stripes of the same color, one on each side of the body. Some varieties have red or black spots between the dorsal stripe and the two side stripes. This is an extremely variable species, and even experienced herpetologists often struggle to identify it correctly. Western terrestrial garter snakes are medium-sized, with a typical total length ranging from 46 to 104 cm (18 to 41 inches). Like many North American garter snake species, the western terrestrial garter snake has mildly venomous saliva. When venom from specimens collected in Idaho and Washington was injected into mice's gastrocnemius muscles, it produced myonecrotic, or muscle tissue-killing, effects. Several cases of mild human envenomation, which caused local edema and other symptoms with no systemic effects, have been recorded from the wandering garter snake subspecies of this species, including incidents in Colorado. This species is the only garter snake with a well-documented tendency to constrict its prey, though this constriction is less efficient than that seen in many other snakes, such as the gopher snake. Its constriction uses disorganized, loose, sometimes unstable coils and takes longer to kill prey. Colorado populations of the western terrestrial garter snake appear to kill prey more efficiently via constriction than Pacific Coast populations of the species. The geographic range of Thamnophis elegans covers central British Columbia, central Alberta, and southwestern Manitoba in Canada. In the western United States, the species ranges as far east as western Nebraska and the Oklahoma Panhandle. One isolated population of the species exists in Baja California, Mexico. This snake occupies a wide variety of habitats, including grasslands, woodlands, and coniferous forests, at elevations ranging from sea level up to 3,962 m (12,999 ft). It is primarily terrestrial, though populations living in the Great Basin and Rocky Mountains are semi-aquatic. Unlike egg-laying snake species, the western terrestrial garter snake is ovoviviparous, a reproductive trait common to natricine snakes. Females give birth to broods of 8 to 12 young in August and September each year.
