California Gulls are the most common gull species in the South San Francisco Bay, especially during the breeding season. Since 1980, our biologists and citizen scientists have monitored California Gull populations in the South Bay, and documented a dramatic increase from less than 50 breeding birds in 1980 to over 50,000 breeding gulls in 2014. California Gulls may have negative effects on other ground-nesting birds and have been found to be significant predators on American Avocet, Black-necked Stilt and Western Snowy Plover eggs and chicks.
However, recently, gull numbers have been decreasing in the Bay Area. The former South San Francisco Bay salt pond where 23,000 California Gulls nested until 2010 (Pond A6) was restored to tidal action in December 2010. Many of the gulls, presumably displaced by the restoration, moved to new nesting colonies in Alviso. This survey helps us determine if and where displaced California Gulls establish new colonies. In addition, we banded over 10,400 California Gulls since 1983, and over 1000 of these at Pond A6 before the levee was breached in order to track their movements.
Partners for this research project are the Don Edwards San Francisco Bay National Wildlife Refuge and the U.S. Geological Survey. Funding is provided by SFBBO members and donations from the community.
Gull Volunteer Opportunities
Our annual gull survey happens during two days in May each year and is primarily conducted by citizen science volunteers. Volunteers receive training on the day of the event and join our biologists to visit nesting gull colonies in the Bay Area. We also need help from the community to find new colonies and re-sight banded gulls. Visit our Volunteer section to learn how to volunteer for the survey or report banded gulls.
Gull Outreach and Education
In addition to working with partners and leading citizen science efforts, our waterbird team offers a robust shorebird outreach program. Our biologists offer science talks as well as bird walks in the field to educate youth and the general the public about gulls. They also teach gull identification workshops and offer hands-on gull science activities at family science and other community events. Visit our Events section to learn about our shorebird education activities.