Each spring, shorebirds come from as far south as Argentina and concentrate at the muddy tide flats of Grays Harbor Estuary. In recognition of the importance of this critical shorebird habitat, Grays Harbor Estuary has been named a Western Hemisphere Shorebird Reserve Network Site of Hemispheric Significance. About two dozen species of shorebirds use the Grays Harbor Estuary. The five most abundant species are the Western Sandpiper, Dunlin, Short Billed and Long Billed Dowitchers, and the Semi-palmated Plover. From June through October the shorebirds return to the estuary on their way south but in lesser concentrations.
Thousands stay for the winter.
The Refuge is located in the northeast corner of the Grays Harbor natural estuary and is managed by the U.S. Fish and Wildlife Service. It encompasses about 1500 acres of intertidal mudflats, saltmarsh, and adjacent uplands. The Refuge's mudflats are the last areas in Grays Harbor to be flooded at high tide and the first areas to be exposed as the tide recedes. This gives shorebirds extra time to feed. Shorebirds must peck or probe almost continuously to obtain a constant supply of food.