• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Gull sp. San Francisco, CA, USA (1 Viewer)

Metbirder

Registered User
Hi all,

I saw this gull sp. yesterday (May 20th) at Stow lake, Golden Gate park, San Francisco, CA and it has stumped me.

The bird associated with the Western Gulls that were present, and in flight it gave the impression of pale primaries. I have had various ideas on what it could be including Glaucous Winged Gull (though I am not convinced due to the primaries appearing slightly darker than the rest of the body). I have also thought Thayer's gull and even the possibility of a hybrid, though I would not be sure what the parent species would be.

David
 

Attachments

  • IMG_0419.JPG
    IMG_0419.JPG
    124 KB · Views: 62
  • IMG_0425.JPG
    IMG_0425.JPG
    134.9 KB · Views: 60
  • IMG_0434.JPG
    IMG_0434.JPG
    94.7 KB · Views: 53
  • IMG_0449.JPG
    IMG_0449.JPG
    110.1 KB · Views: 76
it's a 2cy western or western x glaucous-winged, probably not definitely ID-abele. thayer's is out with such a strong bill. at this time of year, 1st to 2nd cycle large gulls often are strongly bleached including primaries, like in your bird. the paleish looking primaries are bleached.
 
well peter - not only that it can be strongly bleached, all pics are also strongly overlit in the pic, so i'm reluctant to make a call on paleness alone...
 
Western Gull is a species that moults rather quickly out of juvenile plumage, acquiring a variable number of dark grey scapulars in its first winter already. The bird in the original post here has acquired a few grey scapulars (as it is late May already), but they are not dark.
They can be compared to adult Western Gull in the back of the last photograph and in this photo, and they certainly appear a lot paler.
 
Last edited:
Thanks Lou!
There is an enlightening series of photographs in Gulls of the Americas showing plumage development of 1st to 2nd cycle Western Gull throughout the year, on pages 34 to 38.
 
Warning! This thread is more than 12 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Users who are viewing this thread

Back
Top