Overview
The Northwestern Garter Snake (Thamnophis ordinoides) is a gentle, charming, and extraordinarily polymorphic harmless serpent native to the lush maritime habitats of the Pacific Northwest. Famous among herpetologists as one of the most colorfully variable snakes in North America, this docile garden ally specializes almost exclusively in hunting garden slugs and earthworms beneath damp fern fronds and blackberry thickets.
Biology and Physical Characteristics
Thamnophis ordinoides is a small, slender colubrid with a small head barely wider than its neck and large round eyes with dark pupils. Its color pattern is breathtakingly diverse: individuals may display a vivid yellow, neon orange, fire-engine red, turquoise, or chalky white dorsal stripe set against a slate-grey, velvety black, chocolate-brown, or olive background, often accompanied by checkered flank spots.
Behavior and Ecology
Unlike its aquatic cousin the common garter snake, the Northwestern Garter Snake is strictly terrestrial, rarely entering water. It is a dedicated slug specialist, using specialized curved rear teeth and copious lubricating saliva to overcome and swallow sticky, mucus-covered banana slugs and garden slugs. When startled, it rarely bites, relying instead on release of a pungent musky cloacal secretion before fleeing into dense grass.
Conservation and Human Impact
Classified as Least Concern by the IUCN, Thamnophis ordinoides is abundant throughout western Washington and Oregon, frequently flourishing in urban greenways, city parks, and home gardens where it provides natural pest control by regulating invasive slug populations. It is live-bearing (ovoviviparous), giving birth to up to 20 fully formed miniature young in late summer.
Interesting Factoid
The Northwestern Garter Snake is the ultimate color chameleon of Pacific serpents: two sibling snakes born from the very same mother can look completely different, with one sporting an electric flame-red stripe and the other a neon turquoise-blue stripe.