KEY NORTH AMERICAN MIGRATION SITES FOR
Red Knots & Semipalmated Sandpipers

San Francisco Bay 

Country: USA

Region: California,

Site: San Francisco Bay 

Species/Sub-species: REKN-roselaari

Total biogeographic population: 21,770

Count Method: Total estimate

Count: 1,0111

% biogeographic pop. at site: 4.64

Season (primarily): Winter

Site recognition: WHSRN Ramsar IBA

Known threats: Approximately 85% of the marshes have been lost to salt pond conversion, agricultural diking, and filling for urbanization. Development pressures are a threat. The sediment dynamics in the Bay have been dramatically altered by upstream land use. There are current discharges as well as legacy pollutants accumulated from past discharges. Mercury is carried in runoff from Bay Area and Sierra Nevada gold mining. Selenium enters the bay from oil refineries and agricultural effluent. Oil spills pose a severe, acute and long-term risk. Discharges and spills from wastewater and sewage treatment plants are a threat. When Spartina alterniflora is overgrown, the invertebrates that live in the mudflats disappear, and food sources decline for shorebirds. Another threat is posed by invasive plant species and the algae Sargassum muticum (Japanese Wireweed) as well as invasive animals. Climate change represents a suite of challenges.2,3

Sources: 1Carmona, R., N. Arce, V. Ayala-Perez, A. Hernández-Alvarez, J.B. Buchanan, L.J. Salzer, P.S. Tomkovich, J.A. Johnson, R.E. Gill, Jr., B.J. McCaffery, J.E. Lyons, L.J. Niles, and D. Newstead. 2013. Red Knot Calidris canutus roselaari migration connectivity, abundance and non-breeding distribution along the Pacific coast of the Americas. Wader Study Group Bulletin 120(3): 168–180. 2Ramsar fact sheet: https://rsis.ramsar.org/RISapp/files/RISrep/US2097RIS.pdf 3Ayres, D. R., D. L. Smith, K. Zaremba, S. Klohr, and D. R. Strong. 2004. Spread of exotic cordgrasses and hybrids (Spartina sp.) in the tidal marshes of San Francisco Bay, California, USA. Biological Invasions 6: 221-231. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.476.2004&rep=rep1&type=pdf