Tomales Bay supports roughly 20,000 shorebirds in early winter, qualifying as a wetland of international importance by the Western Hemisphere Shorebird Reserve Network.

The area supports up to a third of the wintering shorebirds along coastal Marin and Sonoma counties. The most abundant wintering shorebird species on Tomales Bay are Dunlin, Western Sandpiper, Least Sandpiper, Marbled Godwit, Willet, and Black-bellied Plover.

Tracking seasonal populations

Since 1989, Audubon Canyon Ranch has been monitoring seasonal populations of shorebirds on Tomales Bay. Three baywide counts are completed within each early-winter and late winter census period, and an additional baywide count is conducted each August and April to record peak numbers of fall and spring migrants.

We have divided Tomales Bay into 14 shorebird count areas, which are covered simultaneously by teams of qualified volunteer field observers. Each count requires 60-90 minutes to complete. Some counts are coordinated to coincide closely with counts conducted by other investigators in other areas.

We use the Tomales Bay shorebird survey data in quantitative assessments of species status, distribution, and trends (e.g.,  Kelly 2001, Kelly and Stallcup 2003), habitat values (Kelly 2001), and progress in local wetlands restoration (Kelly and Condeso 2017).

The results provide information for regional planning and are made available to other investigators through electronic data access (e.g., California Avian Data Center).

Get involved

For more information on becoming involved in any of these volunteer efforts, contact the Cypress Grove Research Center at 415.663.8203.