Washington State’s geography, ranging from the temperate rainforests of the Olympic Peninsula to the arid shrub-steppe of the east, creates a variety of ecosystems that support a rich diversity of animal life. The Cascade Mountains divide the state, leading to distinct wildlife populations in the western, wetter regions and the drier, mountainous interior. This environmental variation allows the state to host species adapted to marine, alpine, forest, and desert-like conditions.
Large Mammals of the Washington Interior
The vast forests and alpine meadows of Washington’s interior, including the Cascade and Olympic mountain ranges, are home to several large mammal species. The Roosevelt Elk, the largest elk subspecies in North America, is primarily found west of Interstate 5, thriving in the coastal rainforests of the Olympic Peninsula. They are generally larger and darker than the Rocky Mountain Elk, which inhabit the eastern side of the state.
Washington supports a large Black Bear population, estimated to be between 35,000 and 50,000 individuals, one of the largest in the contiguous United States. These adaptable omnivores emerge from hibernation in mid-March, feeding on grasses and tree sapwood until summer berries become available. The state is also one of the few places in the lower 48 to host Grizzly Bears, though their numbers are extremely limited.
The small Grizzly population is split between the North Cascades Ecosystem, where fewer than ten bears reside, and the Selkirk Mountains in the northeast, which supports about a dozen individuals. Cougars, the state’s largest cat, are found across the Cascades and Olympic Mountains, with an estimated population of around 2,500. These secretive predators prefer rocky terrain and dense forests, preying primarily on deer and elk. Mule Deer are common across the central and eastern portions of the state, inhabiting open forests and scrublands.
Marine and Coastal Ecosystem Inhabitants
Washington’s extensive coastline, encompassing the Pacific Ocean and the Puget Sound, harbors a diverse array of marine mammals and fish. The orca population is divided into two distinct groups: the Southern Resident and Transient (or Bigg’s) populations. Southern Residents are fish-eaters, relying heavily on Chinook salmon, and their endangered population is estimated at only 74 to 83 individuals.
Transient orcas are marine mammal-eaters whose diet includes seals and sea lions, and their population is increasing in the Salish Sea. Gray Whales are seasonal visitors, appearing along the Olympic Coast from April to late summer to feed on bottom invertebrates. Pinnipeds are year-round residents, with Harbor Seals being the most common, often resting on shorelines and feeding on fish and squid.
The annual Pacific Salmon runs involve several species migrating from the ocean to spawn in freshwater rivers.
- Chinook salmon runs typically peak from July through September.
- Coho salmon are most abundant from September into November.
- Sockeye salmon return during the summer months.
- Chum salmon runs occur later, peaking from October to December.
Avian Species and Raptor Populations
Washington’s position along the Pacific Flyway contributes to a wide variety of bird life, with over 500 species observed. Raptors are particularly visible, with the Bald Eagle being a prominent year-round resident and a significant winter visitor. Large concentrations of Bald Eagles gather along salmon spawning streams, such as the Skagit River, between October and March to feed on fish and carrion.
Osprey are common, nesting near water bodies where they hunt fish, and Peregrine Falcons inhabit urban areas, utilizing tall buildings for nesting sites. The owl population is diverse, with over a dozen species present, ranging from the adaptable Great Horned Owl to the secretive Spotted Owl. The threatened Northern Spotted Owl is dependent on the old-growth forests of Western Washington for nesting and shelter.
Herpetofauna and Smaller Terrestrial Wildlife
The state is home to 26 species of amphibians and 28 species of reptiles, primarily concentrated in the warmer, drier habitats east of the Cascades. The only venomous snake is the Northern Pacific Rattlesnake, found exclusively in Eastern Washington’s drier regions. Non-venomous Garter Snakes, including the Common and Northwestern species, are the most widespread, often found near moist environments like ponds and streams across both sides of the mountains.
Amphibians thrive in the moist western portions, with the Pacific Treefrog being the most common and smallest frog species found throughout the state. Salamanders include the Northwestern Salamander, which lives west of the Cascades, and the Pacific Giant Salamander, which inhabits cold mountain streams. Among smaller terrestrial mammals, the Olympic Marmot is the official endemic mammal of Washington. This highly social, cat-sized rodent is found only in the alpine elevations of the Olympic Peninsula and hibernates for approximately eight months.