Audubon Canyon Ranch conducts ongoing waterbird surveys, begun in 1989, to track the health of shorebird and waterbird populations on Tomales Bay.

Every year, ACR coordinates and trains teams of qualified volunteer birders to conduct four boat-based waterbird surveys on Tomales Bay. Each survey is conducted by 15-20 observers on three boats. The project requires several land-based counts and intensive, baywide observations to assess the number and distribution of waterbird species. 

A science archive

Survey results are maintained in a long-term database, and are used to produce periodic scientific assessments of waterbird species status, distribution and trends (e.g., Kelly and Tappen 1998, Kelly and Stallcup 2003).

Technical reports and electronic data access provide key biological information for regional planning and the protection of Tomales Bay. For example, the project results provided the key information used to designate Tomales Bay as a Ramsar Wetland of International Importance.

Up to 35,000 waterbirds spend each winter on Tomales Bay, with surf scoters, bufflehead and greater scaup the most abundant. Compared to other coastal wetlands in California, Tomales Bay is a particularly important winter habitat for red-throated loons, common loons, eared grebes, horned grebes, black brant, surf scoters and black scoters.

With the exception of San Francisco Bay, Tomales Bay may provide the most important winter habitat for bufflehead on the Pacific Coast south of the Columbia River. 

As human activity continues to increase in Tomales Bay and its watershed, habitat conditions for waterbirds are affected in numerous ways. Such influences suggest opportunities in conservation science. ACR’s waterbird surveys provide scientific information that can help us respond to associated implications for conservation, including:

  • management and control of recreational disturbance to waterbirds
  • the effects of the herring fishery and oyster culture
  • protection of eelgrass beds
  • water quality
  • management of human land use in the watershed

Get involved

Visit the program's volunteer page for more information.