No, they're not "gardner snakes" or "garden snakes." They are garter snakes, named after the striped garters that embellished many a lady's leg in the distant Twentieth Century. A snake that bites, thrashes around, and emits a foul-smelling fluid when handled probably wouldn't make a very good garter, however.
The first stage of predator avoidance is to flee, and snakes—notwithstanding their lack of legs—are superb at that. If not entirely out in the open, as for example when they cross roads, they quickly disappear into the vegetation when disturbed. If captured, the larger ones have no hesitation about biting to defend themselves. A bite from the many sharp teeth of just about any snake will bring out a series of four-letter Anglo-Saxon words such as "ouch" and "rats."
Whether they bite or not, some snakes are sure to wind their body around the captor (or the captor's arm, in the case of a human) and discharge a smelly fluid consisting of mixed feces and urine and a musk produced in the cloaca. If you must catch one, securing the tail is just as important as grabbing the head.
Most garter snakes have a middorsal pale stripe and a pale stripe low on either side. No other common northwestern snakes share that pattern. Although the scales on their underside are smooth, garter snakes have keeled dorsal scales, which gives them a rough appearance and feel. They are rarely more than three feet in length, and most are much smaller.
There are three common species of garter snakes in the Pacific Northwest, but there is sufficient variation in all of them that identification is not always easy. The Common Garter Snake (Thamnophis sirtalis) occurs all across North America. The ground color is dark, with the typical light stripes. Our populations usually have red spots along the sides, but the darkest individuals can show very little red; look closely. In western Oregon and southwestern Washington, the head is largely reddish.
Western Terrestrial Garter Snakes (Thamnophis elegans), widespread in the West, never show any red markings. Populations in our region characteristically show a series of alternating dark spots in a checkerboard pattern on a lighter ground color, still with the normal three stripes. There are melanistic populations in the Puget Sound region, some individuals almost entirely black.
Northwestern Garter Snakes (Thamnophis ordinoides) are restricted to the Pacific Northwest, mostly west of the Cascades. They are smaller than the other two species, with a relatively smaller head. The head is somewhat lighter than the body, with a contrasting dark stripe through the eye. This species is very variable, from very dark with contrasty yellow stripes to a lighter color with dark markings not so different from those of a Western Terrestrial. Some individuals have a red dorsal stripe or are largely reddish above, unique to this species.
Common and Western Terrestrial Garter Snakes eat mostly vertebrate prey, especially fishes and amphibians, but both may take any other small animals that they come upon. Because of their primary diet, they are commonly found around water, even in it (notwithstanding "Terrestrial" in the name). Northwestern Garter Snakes are invertebrate feeders, capturing mostly slugs and earthworms. This correlates with their smaller head and mouth and entirely terrestrial existence.
Garter snakes are common throughout the warmer parts of the year. They disappear by October, sheltering underground where possible. Sometimes numerous individuals den together, perhaps conserving body heat by being tightly packed. They are often the first snakes to appear in spring, sunning themselves in exposed places near where they spent the winter in dormancy. Like all reptiles, they use the sun for thermoregulation.
Garter snakes are the only common snakes in the wetter parts of the Pacific Northwest, and they are often found in suburban parks with natural habitats remaining. Their continued presence is a great reason to preserve those habitats.