Sunday, April 4, 2010

Bird ID Challenge # 3

This photo was taken on the San Luis Obispo County coast in February. Please let me know your IDs and the reasons for them by clicking on "comments" at the bottom of this post and then posting your thoughts. I will post what I think the IDs are on Wednesday evening, but gulls are admittedly not my strongest area of identification so I will be interested in your comments. Have fun.
See the "comments" for my ID, which is rather tentative for the back gull.


  1. Am enjoying reading this Jim.

    Good to see you're on on the mend after your tumble.

    Do most on my stuff on foot close to home, but after reading how much ground you cover, i may well be inspired to jump in the saddle & give it a try.

    Regards Stevie

  2. Thanks. I hope you get on the bike and expand your territory. Just watch out for the crazy drivers!

  3. Well, I'll take a stab at it. Both look like first cycle gulls with whitish to brown (not black) primary tips. The one in back has pale edging to the brownish primary tips. I suspect that one or both is a Thayer's Gull. I'm not sure I can rule out Glacuous-winged Gull or hybrids completely?

  4. It's hard to tell from these photos, but the lighter gull seems to fit Thayer's better. It has a tail darker than the back color indicating the possibility of a tail band. It also has the clean 'marbled' pattern on the back and secondaries, along with a smaller head and bill.

    The darker bird looks bulkier, with a larger head and bill; it's tail and back color match and it doesn't show a clear 'marbled' pattern.

    So, lighter bird is first cycle Thayer's, the darker bird is a first cycle Glaucous Winged.

    Now, to see if I'm right! :-)

    Steve G.

  5. The front gull appears to be a fist winter Thayer's Gull - a light one. The relatively slender bill with the brownish wing tips is consistent with Thayer's and it appears smaller bodied with a more rounded and smaller head than the gull behind it. The bleached wingtips are lighter than the more protected primary bases. Also, the fine diffuse pattern in the scapulars is good for Thayer's.

    The back gull is more of a problem. It would appear to be a hybrid first winter larger gull. The wing tips are too light for Western or Herring Gulls, but the wing tips and wing coverts are contrastingly darker, which is inconsistent with Glaucous-winged. This bird has a thick bill, but it has a lighter base and a lightish head which is probably better for Herring X Glaucous-winged than Western X Glaucous-winged. Any additional thoughts on this bird or the front one??