Swallow-tailed Gull , San Mateo, California, San Gregorio SB, San Gregorio, 01 September 2023
Mega rarity found this afternoon by Aaron Maizlich and seen by many observers until dusk. A Galapagos near endemic this species wanders south to waters off central Chile, but rarely heads north where it has occurred in California six times previously with the first record in Monterey Bay in 1985. This unique species is in its own genus. Unlike other gulls, they forage at night. To help with night vision they have exceptionally large eyes outlined in red as seen here. This appears to be an adult in full breeding plumage, presumably displaced by unusually warm water around the breeding grounds.
© Joe Morlan