Washington state offers a wide diversity of waders. Lying directly on the Pacific Flyway it contains a number of staging areas for the millions of birds that pass through the area each Spring and Autumn on their way to and from breeding grounds in Arctic Canada, Alaska and across the Bering Straits to Northeast Siberia. Within the state there is also a large contrast between the sage brush steppe and desert east of the Cascade Mountains to the wetter forests and estuaries that border Puget Sound and the Pacific Ocean.

Grays Harbor, Willapa Bay and the mouth of the Columbia River in the Southwest corner of the state are internationally important sites for Western Sandpipers, Red Knot, Black-bellied Plover and Short-billed Dowitcher. The more sheltered waters of Puget Sound and the river deltas support slightly smaller numbers of birds though with greater diversity. In Spring birds migrate along Puget Sound up to the important staging area along Boundary Bay just across the border next to Vancouver while in Autumn the patchwork of ponds and rivers are great places to look for vagrants which are much harder to find on the larger estuaries.

East of the mountains is almost a different world. Lying in the rain-shadow of the Cascade Mountains the dry sage-brush desert is punctuated by a network of canyons, lakes and marshes formed by glacial meltwater carving through layers of basaltic lava laid down between 10 and 30 million years ago. Black-necked stilts, American avocets and Wilson's phalaropes breed on the more saline ponds. Wilson's snipe are common in freshwater marshes and small (and sadly, decreasing) numbers of long-billed curlews can be found on the marginal farmland and what is left of the wetter areas of the sage brush grasslands.