Clark's Grebe - Is 22 - Oct 24

[Ben]

Update: could by a hybrid WE x CL. Thoughts? Concesus is yes

There was a Clark's Grebe at Island 22 this morning.
It was hanging out with 2 WEGR along the trail just north of the bike park. (east of the boat launch)



It makes it easy to see the differences when they are right next to each other...

[Gord]

Jon I think you're good with this guy being all Clark's. The bill is nice and yellow and no darkness on the bottom of the bill. Winter birds get a bit dusky around the eye but the lores (between eye and bill) nice and white. I found it this evening, also at the boat launch, and got some photos in the fading light. Thanks for the text about it; fun to hear of your discovery.

019_3850 by Gord G, on Flickr

019_3848 by Gord G, on Flickr

A Western Grebe below

019_3853 by Gord G, on Flickr

[Gord]

It is being seen again right in the boat launch today.

[Chris]

Jon, great sighting. I believe this is a Clark's Grebe as well.

[Randy]

Out of curiosity what was the argument for hybrid? Based on what I can find in Sibley's and Kauffman's the most reliable way to tell is bill colour... This one clearly is quite yellow...

[Ben]

I originally posted it as being Clarks, but the amount of white by the eye was a bit concerning to me. Review of the books say thats fine, but with my pictures I don't see it being "clearly" yellow. As opposed to somewhat yellow. When I saw the bird it did stand out. Just thought I'd take the cautious route.

[Gord]

Jon, always a good to examine closely. Plus, lots of learning opportunity to examine things in detail.

Hybrids are a complex matter. Anyone who looks at gulls knows this all too well. I think we're ok with this grebe starting with that nice school bus yellow bill. No dusky olive or otherwise dulling it down like might be expected on a hybrid and especially now when bright breeding colours are more subdued. It would have been nice to see a bit more white around the eye but some dusky colour is expected at this time of year. Also, the photographs may have slightly exaggerated exactly how dark it is based on lighting and angle? Thickness of black neck (thicker on Western) is a fieldmark but subjective once again given the angle of the bird to the camera. My photos above show this very well. One shows pretty much what it should look like and the next where it's slightly turned looks thicker.

On Cornell's All About Birds they have a photo that is pretty much exactly the same as yours, Jon. I will link to that photo below. If they're satisfied this is a Clark's then it's hard for me, who has limited experience with this species, to argue it.




The next photo, also from Cornell, is of what we would like a Clark's Grebe to look like. This would be a summer bird when they're at the easiest.




Still, it's not to say that this might actually be a hybrid and perhaps a second or third generation one but falls outside of field observation to determine with present knowledge. I wouldn't worry about it. Many of the Townsend's Warblers we see actually have decent amount of Hermit Warbler DNA in them. Unless there's some visual traits, I don't worry about calling it a Townsend's despite that knowledge.

Jon, thanks for finding it not just for the cool find but also the great learning opportunity it has presented. It was there again yesterday evening by the way.

[Ben]

Continues this morning

[Gord]

I didn't notice it, pure or hybrid, yesterday or today. It may have moved on to confuse birders elsewhere.

[Gord]

So, the consensus is in on this guy and it is indeed a hybrid. It was an educational experience and I appreciated open and in-depth the responses I got from people who are likely busy with work and the last thing they need is me bugging them. I had an interesting dialogue with Steven Mlodinow who had done a paper on the very topic and whom I figure would know what's what. I will give a link below to his paper as it's very good reading. The dark on the eye of the bird is what shows the Western influence. The rest of the bird looks pretty good. Must be a backcross of a hybrid with a pure Clark's? At least it's not just the gulls we have to worry about anymore.

Jon, good find all the same; it was a good opportunity to explore the topic.

cobirds.org/CFO/ColoradoBirds/InTheScope/84.pdf