Yesterday I posted some “photo clips” from video footage that I took of a unique and interesting warbler that we found on one of my local bird walks at Point Reyes, Marin, California on November 12th 2014. Here is the complete video. Check it out and please feel free to comment on it if you have any ideas or thoughts as to what it might be.
Bloggerhead Shrike 
Hi Keith — this is so cool! I’m leaning toward a Black-throated Green x Townsend’s hybrid, but looking at the cell phone photo you posted yesterday I’m seeing more grayish tones than I see on your video. and the lack of yellowish wash on the flank is of interest — but then these aren’t the greatest images to work from. Assuming it’s a male — based on the extensive black across the upper breast and throat, and thick side-streaks — we’d expect either Townsend’s or BT Gray to have a largely black crown. But this bird’s green crown is quite different than that of either a male TOWA or BTGray, and I really don’t think it’s a female based on the extent of black on the underparts. Some video frames show the lightly streaked back to have fairly bright greenish undertones — also consistent with BTGreen lineage — although the photo from yesterday looks quite a bit grayer. So I’m pretty confident that BTGreen is part of the picture.
What’s perhaps most concerning about TOWA as the other parental species is the way the yellow coloration is concentrated in the upper/forward part of the face — especially in the lores, where BTGray has its yellow spot. I don’t understand why a hybrid involving a TOWA would be lacking in yellow on the lower part of the face. Also, that photo really makes the back look grayish with only a touch of green — not what I’d expect from a hybrid between two green-backed species.
I don’t see any references to hybrids between BTGreen and BTGray, and their ranges don’t overlap, but I’m guessing it wouldn’t be impossible for one of these species to get a little out of range and get busy with one of the locals.
A recent study showed that hybridization between BTGreen wasn’t very unusual in the small zone of overlap between those species:
http://onlinelibrary.wiley.com/doi/10.1111/j.1600-048X.2011.05360.x/abstract
From the abstract: “Analysis of plumage, morphology, and mitochondrial (COI) and nuclear molecular markers (CHD1Z and numt-Dco1) shows surprisingly extensive hybridization between these species, with at least 38% of individuals in the hybrid zone being either hybrids or backcrosses.”
Here’s a photo and video of a presumed male BTGreen x TOWA at High Island:
https://www.flickr.com/groups/hybridbirds/discuss/72157629779523671/
Your bird really doesn’t look much like that. So, all things considered, I will go with the unprecedented BTGreen x BTGray. Any chance of someone getting better photos?!?!?
That first sentence in my long comment should read that I was initially leaning toward BTGreen x TOWA, but then changed my mind about TOWA…
Hi Keith, Could it be a black-throated green warbler?
Carol Trego, New Cumberland, Pennsylvania
Dear Carol, Thanks for your comment about the strange warbler that I filmed out at Point Reyes. Many, many comments have been pouring in about this unique and wonderful bird. Yes, some folks feel that this bird does have some Black-throated Green Warbler in it. However, most people think that it is either a “carotenoid challenged” Townsend’s Warbler or a hybrid between a Townsend’s and a Black-throated Gray Warbler. In any event, I am just so glad that I had my “scope/video camera hybrid” with me! Best wishes, Keith
Another correction to my first post: A recent study showed that hybridization between BTGreen and TOWA wasn’t very unusual in the small zone of overlap between those species.
Robb, Hey, thanks for all of your great comments regarding the “Strange Warbler” out at Point Reyes. I have been getting numerous thoughts from many people as to what this bird might be. The most common feeling is that this bird is either a “carotenoid-challenged” Townsend’s Warbler or a hybrid between a Townsend’s and a Black-throated Gray warbler. In any event, the bird was a beautiful, interesting and unique creature. I was just glad that I was set up with my scope/video camera set up at the time. Thanks again! Keith
Hey Keith — if this were a “carotenoid challenged” TOWA or TOWA x BTGray it should have a predominantly black crown. How are people explaining that aspect of the bird, if they are? I really don’t see how you get away from BTGreen as a parent, just based on the crown. Not to mention the way the black spreads across the upper breast. And if half the genes are from BTGreen, the rest of the bird’s appearance strongly suggests BTGray to me, not TOWA, at least based on the images available (which unfortunately aren’t the greatest).
Hey there Robb,
Yeah, it does kind of put one in a bit of a circular knot. Did you see the video that I posted yesterday on You Tube of the bird? Check it out and hopefully this will show the bird a little better. Keep in mind that the bird was about 150 feet away and I was filming through my scope and so is a bit shaky. You can see it here. https://www.youtube.com/watch?v=aVK2OWgm7LI
Let me know what you think. I can’t wait to hear your thoughts. Keith
Hi Keith, I was commenting on the video mostly. It clearly shows that the bird’s crown is predominantly olive(ish), with a bit of black along the border with the supercilium. This would be consistent with a male BTGreen (olive crown) x either TOWA or BTGray (both with predominantly black crowns). I don’t understand how a male TOWA x BTGray could have an olive crown with just a bit of black on the border — it should be predominantly black. And if TOWA was crossed with BTGreen, I don’t understand why the lower part of the face would be lacking in yellow and why back would be so gray along the margins (best visible in the one cellphone photo, but also discernible in your video). I don’t think it’s a circular issue — just my interpretation of the two species of warbler most likely to combine to show the features that this bird appears to show. With the olive crown and the black spreading across the upper breast the way it does on this bird, I don’t understand how we get away from BTGreen as one of the parents (assuming it’s a male, as it seems to be based on the extensive amount of black on the throat, upper breast, and side-streaks). After that, BTGray makes much more sense to me than TOWA does, and anything else makes even less sense to me. I am truly interested in the analyses that others are making that lead them to other conclusions — will they post their thoughts or allow you to do so?
Robb, Thanks for your thoughts regarding this bird. I chatted with Peter Pyle this morning and he came up with the same thoughts as you have. While I won’t put names here regarding each persons thoughts as to what this bird is, there are MANY ideas. The most common is, “Black-throated Gray X Townsend’s Warbler, followed by Townsend’s lacking much of its yellow, to BTGray X BTGreen, Cerulean X BTGreen, to TOWA X Hermit, to TOWA X Myrtle even TOWA X Yellow-throated and BT Gray X Golden-cheeked! So, you can see that folks have many ideas. I don’t know if I can offer much more than that. Best Keith