08/17 -- Oakland Middle Harbor -- Common Tern
There was an amazing aggregation of 472 ELEGANT TERN. They occupied nearly every exposed sand bar between the mid-morning high tide and the early afternoon low tide.
While counting the Elegant Tern, I noticed a much smaller tern with a slim, red bill standing on nearby exposed sand and mud. The cap was black and extended the length of the nape with just a hint of white speckling on the forehead. I immediately suspected this was a COMMON TERN.
When this individual took flight, a dark wedge was seen on the upperwing on the outer primaries. Even after careful consideration, I found nothing to invalidate my initial identification.
It was later joined by similar individual that I did not observed in flight, but its cap and bill were similar. Although, this second individual did have a slightly more stout bill.
Several FORSTER'S TERN were seen on a more distant sand bar. These had already advanced towards basic (nonbreeding) plumage.
The checklist is here: