The Grebe that wasn’t: Rushed Conclusions and Shadowy Identifications

FINAL IDENTIFICATION OF THIS BIRD ON HOLD, HOPEFULLY MORE TO COME!!!

There is no doubt that there is an Aechmophorus grebe in Harris Co., several observers were able to catch up with the bird in Tabbs Bay today and obtained good views. What is in doubt is the species specific identification. While I was certain to call it a Western Grebe the previous night after looking at my photos and summarizing my field observations, some lingering doubts were confirmed today when other observers noted the likelihood of it being a Clark’s. The poor and distant photos I obtained from the boat last night seemed to corroborate  the field observation, which revealed large amounts of black around the eye. Some folks looking at the pictured agreed: “textbook Western”. John raised some suspicion about the yellow bill and it didn’t quite sit right with me either. Doing some research online I did find photos showing clear Western Grebes with relatively bright bills and I attributed some of it to the late afternoon light. Also, based on records, Western was just much more likely, not a good way though to identify rarities like this. But I had noticed the brightness of the bill far from shore, before we ever got close and took the photos. There also was quite a bit of white visible on the flanks in the field, another character that didn’t sit right with Western.

The new observations and lingering doubts led me to look at the situation with fresh eyes today, unhurried and considering all field marks and my conclusion is that, yes, this is the a Clark’s Grebe indeed. I fell victim to rushed identification, pure excitement, and shadowy photography. Even last night I mentioned to John that some of my poorer photos seemed to show a Clark’s Grebe, I dismissed it to overexposure and bad focus. Looking closer at my photos today, about 50% show the dark around the eye for Western and 50% show no dark around the eye, looking good for Clark’s. So what is going on here? I dismissed some of the poorer photos, but should have paid attention to them, instead of the bill being too yellow and there being too much white due to the light, it was a shadow at certain angles that made the area around the eye appear dark. (And in my defense that is what I saw in the field.) So why the sudden turn around in identification. I went from pretty certain to it being Western to really sure that it is Clark’s. Here are some characters that support the final identification: bright yellow bill and white on flanks support Clark’s, the character supporting Western was apparently a shadow (albeit a strange one and something I have never seen before, see photos), looking closer the is no black below the eye and lores appear clear white, also good for Clark’s of course.

This has been an interesting bird and experience and I appreciate the helpful comments and discussions with other observer that put the identification on the right path finally. Also it was a fun chase across the bay and I am glad other folks got to see it. Some useful things I have learned in addition to how tricky Western/Clark’s identification can be, is the importance of looking at the bird in the field. Let me explain, due to the limited time we had, I concentrated on obtaining “record photos”, thus I never studied the bird while we were close and the “proof” turned out to be a shadowy photo leaving the identification uncertain. If I would have studied the bird closely I feel I would have noticed the extent of white albeit even during close observation the shadow was present and two observers were fooled. Additionally, I will not dismiss other field marks again and weigh all equally, the bill color and white on flanks should have raised more questions and I will pay close attention to all photos obtained even the poorly focused pictures. See the photos below, the top two rows show a bird that looks good for Clark’s, the bottom row shows the same bird at a different angle revealing the dark around the eye apparently due to a shadow. I based my original identification on what I saw in the field and the photos in the bottom row. I suspect that the shadow may be due to the low light and the birds head feathers. All in all a great and even better bird in the end.

Harris Co. Aechmophorus Grebe

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One response to this post.

  1. Posted by Jeff fowler on December 2, 2013 at 12:23 am

    Heads up for you and your birding community. I saw the grebe again yesterday -11/30/13. No doubt about it. It was in almost the exact same place as last year.

    Reply

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