A massive influx of shorebirds begins in late April and continues through mid-May as birds journey north. This is the spring migration, subject of the Shorebird Festival, typically held at the Refuge during the last weekend in April, depending on tides. Hundreds of thousands of shorebirds stop to rest and feed on the vast mudflats in Grays Harbor. After a brief stay, the birds move north along the coast of British Columbia and reach the Copper River Delta in southeast Alaska. Then it's on to their breeding grounds where long days and abundant food resources provide an ideal place to nest and raise their young. While visiting Grays Harbor in the Spring, expect to see large numbers of Western Sandpiper, Dunlin, Short-billed and Long-billed Dowitchers, and Semipalmated Plover, as well as Black-bellied Plover, Red Knot and Least Sandpiper. Western Sandpipers and Dunlin compose 80 percent of the shorebirds present in the Spring.