This morning at Coyote Hills our group was on the trail overlooking the North Marsh, looking due north, when a very large all white gull appeared from the NW. Larger than a nearby Herring Gull. It circled the marsh then flew SW and disappeared.
The bird seemed pure white; the bill was not bi-colored but big and yellow.
What bothers me is the lack of mantle contrast to the rest of the bird. I saw none. An adult Glaucus Gull should have a light gray mantle, albeit lighter than Herring or Glaucus-winged. I saw no such contrast; just immaculate white top and bottom. So I'm puzzled.
The sky was socked in with dark gray clouds and perhaps that accentuated the overall whiteness (seems to do that with Snow Geese which glow under such skies). Could light be the problem?
In the North Marsh among the denizens of Wigeon were two Eurasian drakes.
Lots of birds everywhere:
swarms of Robins feeding on Toyon
a Loggerhead Shrike
an adult female and immature male Harrier
two Green Herons along the canal
a pair of Great Horned Owls in Eucalyptus just east of Hoot Hollow
Lots of water, lots of birds.