Grays Harbor National Wildlife Refuge is an intertidal estuary in western Washington at the mouth of the Chehalis River, whose broad mudflats make it one of the Pacific Flyway’s most important stopovers for migratory birds. Especially vital in spring and fall, this small area contains only about two percent of Grays Harbor’s intertidal habitat yet can support as much as half of the shorebirds staging in the estuary. Up to one million birds gather here to rest and feed, including twenty-four species of shorebirds. Its international designation reflects the refuge’s outsized importance to migration along the Pacific coast and as a gateway to the Olympic Peninsula.