Washington State is home to a single species of venomous snake, the Western Rattlesnake (Crotalus oreganus). This species is also commonly referred to as the Northern Pacific Rattlesnake. While over a dozen snake species inhabit the state, this rattlesnake is the only one considered medically significant to humans. Understanding the specific characteristics and geographic range of this reptile is important for safely sharing the environment, especially in the eastern half of the state.
Identifying the Species
The Western Rattlesnake is a pit viper, distinguished by several physical features. Adults typically range in length from 18 to 48 inches. Their coloration is highly variable, often presenting as a base of gray, olive, tan, or brown, which helps them camouflage effectively within their habitat.
Along the back, the snake displays a series of large, dark blotches, sometimes described as having a diamond shape, which are often outlined by a lighter color. The head is noticeably broad and triangular, a common trait among pit vipers, and is wider than the snake’s neck. They are also equipped with two heat-sensing pits located between the eye and nostril, which aid in locating warm-blooded prey.
The most identifying feature is the rattle, a structure made of interlocking keratin segments at the end of the tail. When the snake feels threatened, it rapidly vibrates this rattle to produce a distinctive warning sound. A rattlesnake does not always rattle before striking, and young snakes may not have a fully developed rattle. Generally, these snakes are non-aggressive and prefer to avoid human contact, only striking when they feel provoked or unable to escape.
Where Rattlesnakes Are Found
Rattlesnakes in Washington State are almost exclusively found east of the Cascade Mountain crest. This geographic division is due to the snake’s preference for the drier, more arid environments found on the eastern side. The population inhabits the shrub-steppe, grasslands, and rocky areas of the Columbia Basin and surrounding ecoregions.
Their preferred habitats include rocky outcrops, talus slopes, and the corridors along rivers like the Columbia, as these locations offer shelter and basking sites. The snakes undertake seasonal movements, emerging from winter hibernation dens, called hibernacula, in the spring. These dens are typically found in rock crevices or abandoned burrows on slopes with good sun exposure.
During the warmer summer months, the snakes disperse from their dens to hunt, becoming more active at dawn and dusk to avoid the midday heat. As temperatures drop in the fall, they return to their communal hibernacula for the winter. Hikers and outdoor enthusiasts are most likely to encounter them near denning areas in the spring and fall.
Encounter Safety and Prevention
The most effective strategy for managing rattlesnake encounters is prevention, which involves being aware of their habitat and adjusting behavior accordingly. When hiking in eastern Washington, wearing over-the-ankle boots and loose-fitting, long pants can provide a layer of protection against accidental bites. It is recommended to stay on marked trails and avoid walking through tall grass or thick brush where a snake may be hidden.
When moving through rocky areas or gathering firewood, never place hands or feet where you cannot see clearly. Using a walking stick to tap the ground ahead or probe around logs and rocks can alert a snake to your presence, giving it a chance to move away. If a rattlesnake is spotted or heard, the safest action is to move away slowly and quietly, giving the snake a wide berth.
If a bite occurs, immediate medical attention is required, and the Washington Poison Center should be contacted to coordinate care. While waiting for emergency services, the person bitten should remain as calm as possible and restrict movement to slow the spread of venom. The affected limb should be kept in a neutral position, ideally below the level of the heart. Any rings, watches, or tight clothing near the bite site must be removed immediately, as swelling will occur.
Crucially, do not attempt ineffective first aid measures that can cause further tissue damage:
- Do not apply a tourniquet.
- Do not cut the wound.
- Do not attempt to suck out the venom.
- Do not apply ice.