[Birdtalk] Comments on Pat's Photos, Please

Wed Feb 28 08:32:01 MST 2007

Pat,

Thanks for your vote of confidence on the ID and may you see the bird again this morning on the trip to Farmington Bay. I await your report with bated breath.

I'm neither offended nor defensive over scrutiny and different opinions as to the identity of this bird. Reporting such a sighting carries with it both an expectation of scrutiny and skeptical reactions because many white-headed gulls, and especially gulls of the Thayer's complex, present supreme ID challenges. As Mark pointed out, some ornithologists are of the opinion that Thayer's and Iceland Gulls are the same species. I share that opinion even as the AOU classifies them as separate. There's great debate in the scientific community these days as to what even constitutes a species.

As I was watching the gull and beginning to take notes on Monday, I knew that I would not be able to submit a sight record to the Utah Bird Records Committee without incontrovertible physical evidence. Your photos are helpful, but that records committee--it's a tough crowd. The committee's process of scrutiny is necessarily a conservative one, meant to preserve the validity of the state's scientific record. I don't think we have enough information between your photos and my notes to defend the Iceland ID, what would constitute a first record for the state. That doesn't mean I lack faith in the ID--I believe we saw an Iceland Gull. 

If you're sure of the ID, you should add the gull to your list. You don't need a consortium of bird analysts to agree with notes and photos to log the bird. 

The debate over the ID is a good thing. ID challenges like this one drive birders to the books and strengthen our ability as a community to identify white-headed gulls. Whose ability to make these calls needs to improve? Everyone's. 

Should anyone see our pale gull again, we'll send Mark a case of Excedrin Migraine so he can deal with the ensuing headache as he comes to the conclusion that an Iceland Gull has finally found its way to Utah, and that the species belongs on the state's record. Ha!

Kris
  ----- Original Message ----- 
  From: Pat Jividen 
  To: westwings at sisna.com ; birdtalk at utahbirds.org ; tanager at timaverybirding.com ; kristinpurdy at comcast.net 
  Sent: Wednesday, February 28, 2007 7:27 AM
  Subject: Re: [Birdtalk] Comments on Pat's Photos, Please

  dfI talked to a friend of mine that teaches photo classes and told him how I took the pictures and he said that I did three major things wrong.  Flash Auto focus, telphoto and that the picture shoud not be juged by the biill and head alone because of that. Tim you know more about that than me but he said because of the angle of the bird the billl would seem larger than usual and evenl the head different, so I think that after being there and four of us tlking about the bird, the bill the  size, and seeing it for over an hour that Kris was right and it was an Iceland.  Pat

----------------------------------------------------------------------------

    From:  Mark Stackhouse <westwings at sisna.com>
    To:  Bird Talk <birdtalk at utahbirds.org>
    Subject:  Re: [Birdtalk] Comments on Pat's Photos, Please
    Date:  Tue, 27 Feb 2007 19:03:24 -0700
    >Curse you Kris!
    >
    >Not because I chased your gull (wish I had time for some birding), 
    >but because of the headache you've given me thinking about this i.d. 
    >problem.
    >
    >I'm beginning to come to the opinion of many ornithologists who 
    >believe that Thayer's Gull is only a subspecies of Iceland Gull. 
    >Even in the adults there is overlap in every character between 
    >nominate Iceland, Kumlien"s, and Thayer's. Many of the features 
    >described in the field guides as being useful for identifying these 
    >species are based upon photos and specimens that are not of known 
    >parentage (that is of unknown origin with regards to the breeding 
    >area - the only "certain" way to tell these forms apart). Therefore, 
    >the identifications of the specimens are based upon the best 
    >considered judgments of the observers/collectors, resulting in a 
    >circularity in the reasoning on  how to identify these species. The 
    >few studies that have been made of birds of certain origin have not 
    >turned up any characteristics or suite of characteristics that are 
    >reliable for identifying these "species."  For example, for years it 
    >was thought that all Thayer's Gulls had dark irises, and both 
    >Kumlien's and nominate (L. g. glaucoides) Iceland had pale irises. 
    >However, studies of birds on the breeding grounds showed Thayer's 
    >with pale irises and Kumlien's with dark irises, and even some 
    >glaucoides with heavy enough speckling in the iris that it would 
    >appear darker in the field. The DNA differences are miniscule to 
    >non-existent - but then they're not great between any of the large, 
    >white-headed gulls. My head hurts.
    >
    >Here in the west we torture ourselves to find a "good" Iceland Gull; 
    >in the east, they do the same to find a "good" Thayer's.
    >
    >With that rant out of the way, your bird looks pretty good to me for 
    >a non-Thayer's Iceland, though it's difficult to see everything that 
    >might be useful from the photos, even though they're a good result 
    >from a distant scope view. The mantle appears pale, and the 
    >primaries patterned (indicating probably a Kumlien's, and not 
    >glaucoides), but there doesn't seem to be much dark in the 
    >primaries, which you would expect for most Thayer's. The dark eye 
    >you mentioned (not visible in the photos) would be better for 
    >Thayer's, but is not definitive. I can't tell about wing length from 
    >the photos, but longer is better for Iceland. I agree with Tim that 
    >the bill and head shape look better for Thayer's (larger, heavier 
    >bill and flatter head), but I just read that these widely-used field 
    >marks are probably indicative of differences between sexes, rather 
    >than species - and if this is true this bird would be a male.
    >
    >Hopefully this bird will show itself again, and give us better views 
    >and photos, so we can really torture ourselves.
    >
    >Good birding!
    >
    >Mark Stackhouse
    >mark at westwings.com
    >801-487-9453 (Salt Lake City, Utah, USA)
    >011-52-323-285-1243 (San Blas, Nayarit, Mexico)
    >
    >On Feb 27, 2007, at 9:59 AM, Kristin Purdy wrote:
    >
    >>I invite discussion on the identity of the possible Iceland Gull 
    >>seen yesterday at Farmington Bay. One analyst has scrubbed the 
    >>photos that Pat Jividen circulated on a birdnet post and suggests a 
    >>Thayer's Gull is a more likely ID for this bird. Please feel free 
    >>to comment!
    >> 
    >>Should the conclusion be that the bird is a Thayer's, I apologize 
    >>for unnecessarily sounding the tweet alarm that sent folks to 
    >>Farmington Bay for a bird classified only as rare. At least I hope 
    >>everyone benefits from the discussion, especially, me!
    >> 
    >>Many thanks to Pat Jividen for capturing these shots. Shooting 
    >>images through a scope without benefit of an adapter is a Herculean 
    >>task, in my opinion, and I'm amazed that Pat was able to 
    >>capture shots that demonstrate several structural characters of the 
    >>bird.
    >> 
    >>Kris_______________________________________________
    >>Birdtalk mailing list
    >>Birdtalk at utahbirds.org
    >>http://utahbirds.org/mailman/listinfo/birdtalk

    >_______________________________________________
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