ANIMAL ESTATE client 5.5: NORTHWESTERN GARTER SNAKE
FOR ANIMAL ESTATE 5.0: PORTLAND
SCIENTIFIC NAME: Thamnophis sirtalis tetrataenia (or Thamnophis ordinoides)
ANIMAL PROFILE: A subspecies of the Garter Snake, the Northwestern Garter is usually between 15-26 inches in length at maturity, being more slender than other garter snakes. Its top is generally dark, in tones of black, blue, brown and gray, marked with stripes of brighter colors, often orange, red, or yellow.
RANGE: Truly a species of the Pacific Northwest. Northwestern Garter Snakes are found west of the Cascade Mountains from the extreme northwestern reaches of California up to Vancouver Island and the coast of southern British Columbia.
HABITAT: The snake is attracted to grassy fields and forest clearings, moist meadows and the edge of thickets. The garter snake is one of the most frequently seen snakes in cities. (link): http://www.northwestherps.com/ordinoides.html
HOME CONSTRUCTION: Northwestern Garter snakes naturally make use of logs for hibernacula (snake dens for winter hibernation), as well as talus (loose rock areas), cracked foundations of buildings, black plastic used in weed control, under old boards and other debris. A suitable dwelling for a snake can be made easily. Hiding spots, such as under piles of logs or leaves, are appealing places for snakes, as are warm rocks for sunning. Snakes can't travel long distances, and as such, a space for winter hibernation must be close to their normal realm.
BUILDING MATERIALS: Logs, stumps, leafs, rocks, brush, and/or wooden boards.
BUILDING MOTIVATION: These benign creatures, rather than posing a venomous threat, play an integral part in a garden's ecosystem. They eat slugs, earthworms, frogs, and mice, among other things. Also, they provide a food source for many birds and mammals. The red-shouldered hawk, in particular, relies on the collection of snakes to help feed their young during the nesting season.
THREATS: Like all snakes, they are feared and too often chased away or killed. However, they are not poisonous, and as a benefit to humans, they specialize in eating slugs (that do a lot of damage in vegetable & flower gardens). A crucial dwelling place for the snake, a down log, is considered a waste of wood, or unsightly, or a fire hazard, or just in the way, and therefore is often removed. A lack of adequate hibernacula is a limiting factor in the success of snake populations.
Snakes fare poorly when we break up natural lands for urban and suburban development and isolate animals that cannot easily move across inhospitable terrain. Near human habitation, humans, domestic cats and dogs, lawn mowers, weed-whackers, and vehicles fatally wound or kill snakes. Aside from these issues, they are naturally preyed upon by badgers, coyotes, foxes, opossums, raccoons, skunks, weasels, great blue herons, hawks, eagles, and owls.
INTERESTING FACTS:
Snakes can't crawl backwards - they can only turn the front half of their body and start moving in the opposite direction
Despite a lack of external ears, snakes can hear. Sound waves are transmitted from the skin on the side of their skull to the jaw muscle to their ear bone.
A snake's sense of smell is of critical importance. Snakes use their tongues to augment their ability to sense smells. Odor particles adhere to the tip of their tongue and are transferred to the roof of their mouth and then delivered to a special chamber for sensing smells. This is why they often flick their tongues in and out.
Garter snakes survive in suburbia and towns because they give birth to live young, and so do not require safe places for their eggs.
Their name comes from their alleged resemblance to the garters once worn by men to hold up their socks.
Garter snakes have lived as long as 18 years in captivity. Such ages might be exceptional for wild snakes, but little is known on this subject.
Garter snakes have toxins in their saliva which can be deadly to their prey. Their bite might produce an unpleasant reaction in humans, but they are not considered dangerous.
Protect hibernation sites and other areas used by snakes.
Mow at slow speeds and be ready to step on the clutch or brake. Leave grass unmowed in places that adjoin a wet area, sunny forest edge, or any other known snake habitat. If the grass has to be cut, survey the area and move or direct any snakes to a safe location prior to mowing. Set the mower blades as high as possible, or use a weed-whacker and leave grass 6 inches high.
Build a small, fish-free (fish eat all stages of amphibians) pond for amphibians. Many snakes, and garter snakes in particular, feed on tadpoles, adult frogs, and invertebrates found in and around ponds (see sources of information on ponds).
Build a rock wall or a rock pile with crevices for snakes to escape from severe weather and predators, to find food, and to give birth.
Create a "snake board" by laying a sheet of plywood or corrugated sheet metal on the ground in a sunny location, propping it up on three sides with 3-inch rocks, lengths of plastic pipe, or similar objects. In cool areas, paint the top black or cover it with dark asphalt shingles to increase the temperature below the board.
Place habitat-enhancement features, such as snake boards and rock piles, away from driveways or heavily traveled roads to avoid vehicle/reptile unpleasantries.
Discourage cats and dogs from using your yard. They are effective hunters and can severely impact snake populations.
Encourage your friends and neighbors to preserve wildlife habitat on their property, especially property that adjoins yours.
Support public acquisition of greenbelts, remnant forests, and other wild areas in your community.
Join a local conservation organization or a habitat enhancement project.
RESOURCES:
Canadian Wildlife Federation / Wild About Gardening
Washington Department of Fish and Wildlife
Photo sources:
large hibernacula illustration