Recognizing its importance to a variety of waterbirds, Audubon recently designated two large portions of San Francisco Bay as globally significant Important Bird Areas. This designation will open up new opportunities for conservation and protection of these vital habitat areas.

The designation follows several months of work reviewing bird data and GIS analysis. The Important Bird Area program is a global initiative developed by Bird Life International and administered by Audubon in the United States in an effort to identify and conserve areas that are vital to breeding, wintering, and migrating birds.

The combined acreage (24,512) of the two new areas is nearly the size of San Francisco!  The northern area is in San Pablo Bay adjacent to the current San Pablo Bay Wetlands IBA, and covers 15,320 acres; the southern area is near San Leandro next to the San Francisco Bay-South IBA and covers 9192 acres. Along with Richardson Bay IBA (3140 acres), these three open-bay (subtidal) sites will represent a habitat type that has received little conservation attention until recently.

Until now, the only designated Important Bird Area was at the 900-acre Richardson Bay Audubon Center & Sanctuary, which hosts between 10,000 and 20,000 migratory ducks, grebes, loons and coots on any given day during the peak of the season. Due to the presence of such large numbers of waterbirds, Richardson Bay was recognized as an Important Bird Area (IBA), and a Marin County ordinance closes the Sanctuary waters to boating activity from October through March each year to protect the birds from disturbance.

For these new areas to qualify as an Important Bird Area, at least 5,000 waterfowl (ducks, geese, swans) needed to be documented as regularly present, and these new areas met that criterea quite easily. Survey numbers for waterfowl often exceeded 15,000 during winter aerial surveys of San Francisco Bay conducted by the U.S. Geological Survey and the U.S. Fish & Wildlife Service.

Globally-significant designation criteria requires observation records of a minimum number of a particular species, and the new Important Bird Areas met that based on the high number of Surf Scoters and Greater Scaup observed regularly. Each of these two diving duck species was regularly counted in excess of 10,000, and well above the required minimum.

Surf Scoter, photo by Len Blumin

One of the reasons for the global emphasis on individual species in the IBA criteria is that some are showing significant downward trends in their populations. One such species is the Surf Scoter—a diving duck seen in the San Francisco Bay and along the coast—appears to be declining at an alarming rate across North America. Over the last 50 years, their total population shrank by approximately 50%.

On Richardson Bay’s Important Bird Area, Audubon staff are working hard to make the bay a safe and healthy place for waterbirds, providing the food and habitat resources they need to survive winter and return to their breeding grounds in the best condition possible. We are working with partners to plant eelgrass, experimenting with herring eggs on kelp, increasing mussel availability, and advocating to remove derelict boats that pollute and damage eelgrass beds.

Now that these new Important Bird Areas have been identified, we can start the process of identifying concrete conservation actions to help protect and enhance the populations of waterbirds that use them. Stay tuned for news and ways you can help.

More information on National Audubon's IBA program can be found at this link; for information on California IBAs, including an interactive map, click here.