Thamnophis elegans
(Western Terrestrial Garter Snake)

Key Characteristics
Three light (yellow to cream) stripes
Black spots often break the margin of dorsal stripe
Ground color usually a olive or greenish-gray
Usually eight labial scales, with 6th and 7th enlarged
Round pupils

General Description:
Different garter snake species can superficially resemble each other.   However, in Idaho, determining which species of garter snake you find is easier than in other parts of the country because we only have 2  species.  A standard method used to distinguish between garter snake species is observing scale patterns.   Western Terrestrial Garter Snakes generally have 10 lower labial scales, and 8 upper labial scales.  The 6th and 7th upper labial scalesClick word for definition are usually enlarged (higher than they are wide), due to the presence of glands in the upper jaw.  The dorsal scales are keeled and their pupils are round.  Western Terrestrial Garter Snakes have a olive to grayish-green ground color dorsally.  The ground color is marked by a light colored (yellow to cream) dorsal stripe that extends from the base of the head, along most or all of the body.   Generally, there is also a single lateral stripe on each side that is similar in color to the dorsal stripe.  The lateral stripes appear to originate on the labial scales, which are similarly colored, and also extend along most or all of the body.  In addition to the stripes, there is usually a series of dark spots that are associated with the stripes and they may break the stripe margin.  Western Terrestrial Garter Snakes have a gray or beige ventral color that may have dark markings concentrated down the mid-ventral line (Nussbaum et al. 1983).   As though garter snake coloration wasn't variable enough, occasionally melanistic (all black) snakes are encountered (Mark Gerber pers. com. 1996, Charles R. Peterson pers. com. 1998).

Western Terrestrial Garter Snakes are medium-sized snakes that can reach up to 107 cm (43 in.) (Storm and Leonard 1995).

Western Terrestrial Garter Snakes generally breed in the spring but fall mating has been reported (Storm and Leonard 1995).  Like all garter snakes, they give live-birth rather than laying eggs.  Usually 4 to 19 young are born between July and September (Nussbaum et al. 1983).

Western Terrestrial Garter Snakes are often found near water, but as their name implies, they can be found away from any nearby water source.  These snakes can be found in habitats ranging from desert riparian areas, to mountain lakes and meadows.

Idaho Distribution:
In Idaho, Western Terrestrial Garter Snakes can be found statewide.

Feeds on slugs, worms, snails, leeches, tadpoles, frogs, fishes, mice, and occasionally, small birds and lizards.  Also eats insects and carrion.

Chiefly terrestrial, but may also be aquatic depending on area.  HibernatesClick word for definition/aestivatesClick word for definition, at times with other species; duration of inactive period varies with local climate.  Species' saliva is reportedly mildly poisonous.  Preyed upon by birds.

Mates in the spring; 4-19 live young are born from July to September, depending on range.



Unprotected nongame species

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Design optimization and revision by Ean Harker ©1999, 2000
Original images provided by Charles R. Peterson and John Cossel Jr. ©1998
Original work by John Cossel Jr. © 1998