Much of the Don Edwards National Wildlife Refuge in southern San Francisco Bay consists of working salt ponds. Caspian terns first nested on levees constructed to contain salt ponds back in 1922, and this was the first nesting record for the species in the Bay Area. What is now Refuge lands near Coyote Hills were used by nesting Caspian terns continuously through the late 1960’s, but intermittently over the last two decades (C. Strong, USFWS, pers. comm.). During 2005-2006, Caspian terns nested on a levee separating two salt ponds (N2A and N3A) within a large salt pond complex on the northeast side of the Dumbarton Bridge, in association with a large and growing colony of California gulls. These levees had been breeched at several spots such that they were no longer connected to the mainland. No nesting by Caspian terns was noted at this site in 2007-2009. In 2008, the U.S. Army Corps of Engineers began implementing the plan “Caspian Tern Management to Reduce Predation of Juvenile Salmonids in the Columbia River Estuary,” which seeks to redistribute a portion of the East Sand Island tern colony to alternative colony sites in Oregon and California. Don Edwards NWR (Ponds N1-N9) is one of three sites in the San Francisco Bay Area where resource managers plan to create or enhance nesting habitat for Caspian terns. Currently, the U.S. Army Corps of Engineers plans to construct two 1-acre islands in two separate salt ponds in the coming years.
