The most common shorebirds using Humboldt Bay are Western Sandpipers, a species that may number in the hundreds of thousands during the peak of their spring migration. In addition to shorebirds, a variety of waterfowl utilize Humboldt Bay, especially Brant; more than 60 percent of the Pacific Flyway population assembles during peak migration stopover (photos by Paul Konrad).

Located in northwest California, Humboldt Bay has been officially upgraded to a Site of Hemispheric Importance within the Western Hemisphere Shorebird Reserve Network, thanks to a comprehensive survey and the collaboration of federal, state, local, tribal, and private partners to conserve this valuable site. A Bay-wide survey of sandpipers, plovers, and related shorebirds during the spring of 2018 revealed that more than 500,000 shorebirds used Humboldt Bay during spring migration alone – a number five times greater than was previously estimated 20-plus years ago.

Humboldt Bay is an especially important spring and fall migration stopover site for remarkable numbers of Western Sandpipers, Dunlins, Least Sandpipers, and other species. It also provides critical habitat for summer nesting sites for Snowy Plovers, Black Oystercatchers, and others; plus it’s a critical wintering area for such species as Willets, Marbled Godwits, Long-billed Curlews, and many more shorebirds.

Humboldt Bay is the second largest estuary in California, providing a vast intertidal zone for foraging shorebirds. One of the primary reasons the Bay attracts so many shorebirds is its diverse array of habitats, from the invertebrate-rich mudflats to salt marsh, rocky intertidal zones, and seasonally flooded agricultural fields, which together provide reliable food resources for a variety and abundance of shorebirds year-round.

Humboldt Bay is one of the most essential stopover sites for migrating birds between Mexico and British Columbia, but it’s not all about shorebirds; for instance, more than 60 percent of Brant utilize the Bay during spring migration, and many of these exciting sea geese pass through Humboldt during fall, and some even winter there, along with a variety of ducks, grebes, and loons.

What attracts the birds? Humboldt Bay, especially the north bay, provides two very important habitats: intertidal mudflats and eelgrass beds. Mudflats fill and drain every day with the tide, creating a rich biodiverse area where many shorebirds feed in enormous flocks at times. Eelgrass beds are also crucial to many species of birds, especially for Brant. Humboldt Bay provides about half of the eelgrass left in California.

For these and many other reasons, Humboldt Bay is also designated as an Important Bird Area of Global Priority by Audubon and their conservation partners, and portions of the Bay are protected by the Humboldt Bay National Wildlife Refuge Complex, which is administered by the U.S. Fish and Wildlife Service.

You can refer to the following articles for more information about Humboldt Bay and its importance to birds at https://whsrn.org/humboldt-bay-upgrades-whsrn-status/ and https://ca.audubon.org/news/humboldt-bay-more-important-birds-you-might-think plus https://www.fws.gov/refuge/Humboldt_Bay/wildlife_and_habitat/HumboldtBirds1.html