Thursday, May 17, 2012

Vireo info from the Vireo Guy!

Risking it all by leaving Pelee today, with no birding plans until May 22 at the earliest.... Seriously dangerous idea considering the warm weather in the forecast - but I'm not totally impressed with the winds... And besides, I plan on being intoxicated to the point that I forget I've ever looked at birds in the first place...... 


Onto the vireo!


The more I learn about these vireos, the more I like them :) So much so, that I've started a "Solitary Vireo" gallery on my picasa ID pages --- and this won't be the last bird you see added there :)

I haven't added the 2006 bird yet, but I'll get around to it eventually.... 

Got some comments from Matt Heindel, who is widely considered the go-to guy for Solitary Vireo questions, which were awesome from start to finish... I asked permission to put them on the blog, and got the green light --- so I hope you enjoy them as much as I did!

Hi Brandon- no bother at all.

This identification just keeps getting harder and I am not sure what subspecies your bird belongs to. Let me discuss some general topics first and then specifics to your bird and why I can't call it a vagrant.

First, this taxonomy is a mess as the powers that be split this into three species without consideration of certain taxa and we know that CAVI and BHVI interbreed in AB, which means we'll have offspring that are tweeners and impossible to correctly assign. A problem rarely discussed is alticola, the Appalachian race, which has much less color than solitarius, and matches your bird fairly well, but I have no clue as to the extralimital records of that taxon. Now, even though I disagree with the AOU did, we have to deal with what we have, which means putting this into one of the slots. The adult males are more slaty, lacking the intensity of blue and green, with diminished yellow; and females and ims are more gray, lacking blue tones, not as green, and with reduced yellow.

A poorly understood tidbit in this complex is the variation in plumage from adult males at the bold end, to im females at the other. This difference is at its maximum in spring, when SY birds are faded. So, some of the items you point out, while good for CAVI, are also indicative of an SY bird. Wing bars are worn, yellow is diminished, etc. So, when comparing it with any adult BHVI (incl female), the adult will look bold and beautiful.

To your bird:
I can see why it got your attention, as it is dull and relatively colorless. No blue tones, no bright green, and little yellow. All features consistent with CAVI. The tough part is determining if it is "extreme" enough to eliminate duller solitarius or alticola, and I can't get there. The lack of head-back contrast is reduced as the age-sex continuum goes to im female, and the same can be said for depth of blue and green, extent of yellow, etc. Wing bars on the bold end are thick and yellow, but on a worn bird, they can be thin and whitish.
You correctly point to the contrast at the malar, but this is a bit of a tweener. While the contrast is marginal at the lower rear border, it is fairly good half way towards the bill and I note how this feature looks better and worse in different photos. The center of throat is snowy white and this runs down towards the bottom of the throat and CAVI AVERAGES more dingy here.

To challenge myself, I approach each potential vagrant claim by reversing the situation, which in this case means, if this were reported from CA as a BHVI, would I accept it? I don't think so. It is on the dull end, and a decent part of the malar has good contrast, snowy throat, etc, but given the interbreeding and mixed offspring, I would feel better saving vagrant BHVI for ones that fit more comfortably in the BHVI bell curve. Your bird fits in the middle of the Solitary Vireo bell curve, meaning it is in between the two bell curves. But, it also could be alticola (SY female probably) and I suspect no one can tell you the likelihood that taxon getting to your area.

So, not only do I wish I could give you what you are looking for, I wish I could more confidently put a name on it. I live in TX, so see plenty of BHVI and if I saw this I would spend a lot of time on it, but I would likely leave it as uncertain, and lean BHVI. Hope that helps, although I suspect it might just muddy things up!
Best regards, matt

Matt Heindel
Fair Oaks Ranch, TX

Got a second comment from him a few days later: 

Sure, feel free to use anything, and you might want to clip this in there, too. 

I checked two resources regarding alticola: Peterjohn does not mention it in his Ohio book. Phillips, in his Known Birds book, has some interesting comments about how some breeding BHVI in New York and PA, look like alticola, although that ssp is not known to breed north or east of West Virginia. at any rate, I still don't know the likelihood of an extralimital record of alticola in ONT, but it does deserve consideration. Their back is typically suffused with gray, so lacks contrast and is generally less colorful. Oh joy- as if solitarius from cassinii was not complicated enough! mh

Matt Heindel
Fair Oaks Ranch, TX

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