This morning at 10 AM, 6 Black Terns flew up from behind the furthest island in Cogswell Marsh, circled the islands for about 5 minutes, then flew off together to the north. All 6 were breeding plumage adults. The 2 Black Skimmers were also present on the island; 2 Ruddy Turnstones were on the rocks at Johnson's Landing; and a Great-tailed Grackle was on the furthest island. Thanks to Bob Richmond for the tip about the best place to set up the scope.
From the Hayward Shoring Interpretive Center, take the East Bay Trail over the first bridge and keep bearing to the right, to the Least Tern sign at the locked gate. This is the SE corner of the loop trail. The islands can be scoped from that point. A map of Hayward Regional Shoreline is available on the net at the EBRPD website.