Wandering Garter Snake. Thamnophis elegans

Description: A slender, elongate snake that attains a total length of between 450 and 1,070 mm. There are usually eight upper labial scales, of which the sixth and seventh are often taller than wide. The internasal scales are usually broader than long. There are two pairs of chinshields of approximately equal length. The dorsal body scales are keeled and the anal scale is single. There are usually twenty-one scale rows at mid-body. The tail is moderately long. The background colour is primarily brown, grey or green, with a dull yellow or brown dorsal stripe, fading posteriorly. Side stripes, generally the same colour as the dorsal stripe, are present on the second and third rows of dorsal scales. Dark spots are generally present between the dorsal stripes and side stripes. The ventral surface is usually greyish, sometimes with darker markings. The underside of the head is white.

Variation: Females are larger than males.

Natural history: Often found near water, but it is not restricted to such locations. When associated with bodies of water, it may be found in close proximity to streams, lakes, ponds, marshes or ditches. In the spring, this species may occur in great numbers. When threatened it may seek refuge in water, beneath debris or in vegetation. It eats insects, molluscs, worms, fish, amphibians, reptiles, small birds and mammals, and carrion. It may bite when captured and / or emit a repulsive secretion from the cloacal glands, along with faeces. Wandering garter snakes are mildly venomous and may immobilize their prey with oral secretions, but the venom has no toxic effects on man. This species occupies communal dens in winter. These may be in naturally occurring crevices or the abandoned burrows of small mammals. Home range size is extremely variable.

Reproduction: The wandering garter snake is a live-bearer. Mating occurs in the spring. Gravid females exhibit low rates of move- ment during gestation and prefer to occupy retreats that provide protection and more suitable thermoregulatory conditions. Four to nineteen young are born from July to September, measuring from 170 to 230 mm in total length.

Distribution: In Alberta, this species is distributed widely south of 52°N, primarily south and west of the Red Deer River. There are scattered localities further north and west along the Athabasca and Peace Rivers. It is broadly distributed in all habitat types, although its status in the more northerly boreal forest sites remains unresolved. It occurs at altitudes of up to 2,000 m and its range overlaps that of both Thamnophis radix and T. sirtalis in south central Alberta. Extralimitally, it occurs from northern B.C. south to New Mexico, Arizona and Baja California. It is present on Vancouver Island. It occurs from the Pacific coast of California and Oregon east to extreme western South Dakota, Nebraska and Oklahoma. Populations at the periphery of the range are fragmented into isolates.

Conservation status: The wandering garter snake remains common throughout much of its range in Alberta, although localized extirpation has resulted in urban areas where wetlands have been destroyed. Such induced patchiness may ultimately prove to be problematic. The status of populations north of 54° requires further investigation.

Remarks: Five subspecies are recognized. Thamnophis elegans vagrans occurs in Alberta. This subspecies accounts for most of the range of the species, but is absent from California, Baja California, western Oregon and western Nevada.

Significant references: Arnold 1977b, 1980, 1981a, b; Ayres and Arnold 1983; Charland 1995; Charland and Gregory 1995; Clark and Chandler, 1992; Clark and Bradford 1969; Feder and Arnold 1982; Fitch 1940,1983; Fox 1951; Garland and Arnold 1983; Gregory 1984a; Mutschmann 1995; Rosenberg et al. 1985a; Rossman et al. 1996; Ruthven 1908; Sweeney 1992; Tanner and Lowe 1989; Thompson 1917; Van Denburgh and Slevin 1918.