[texbirds] Re: Article on Solitary Vireo complex

  • From: peter barnes <pbarnes123@xxxxxxxxx>
  • To: Matt Heindel <mtheindel@xxxxxxx>, texbirds@xxxxxxxxxxxxx
  • Date: Fri, 3 May 2013 10:37:19 -0500

Matt:
Thanks for your updated thoughts about the Solitary Vireo complex. In NE
Texas, I get occasional claims of Cassin's Vireo (CAVI), but I am never
confident that dull Blue-headed Vireo (BHVI) can be reliably excluded. In
looking for your article, I found Don Roberson's comments on separating
these two species (http://creagrus.home.montereybay.com/sovi-id-comm.html).
He says that the dark loral line is the same dark gray shade as the head in
BHVI, but is noticeably darker than the paler gray head of CAVI. Don says
that you didn't think much of this field mark at the time you wrote the
article, and I wonder if you still feel this way, or if your opinion has
changed. Thanks for your thoughts.

Peter


Peter Barnes
Tyler


On Wed, May 1, 2013 at 1:23 PM, Matt Heindel <mtheindel@xxxxxxx> wrote:

> Peter
> Nothing like time to reflect on what is right and wrong with that article
> from (ouch) 17 years ago, but since you are looking at it, let me provide a
> couple of thoughts.
>
> First, it remains a bizarre split to me, given that they did not consider
> intermediate and confusing taxa in Baja CA and Central America. Further, as
> with many species, there is substantial hanky panky in the rockies of
> Alberta (think junco, sapsucker, catharus thrushes, Mourning/Mac warblers,
> etc). There are some birds we cannot identify with certainty given the gene
> flow. In the many years since that piece was published, nothing has changed
> with regard to the incomplete justification of the split.
>
> Digital photography helps with ID, assuming one is satisfied the colors
> are properly rendered. Peter Pyle and I were asked to review a few CA birds
> two winters ago and lucky for me, we were in agreement on the
> identifications. In subsequent exchanges, Peter told me he was feeling
> increasingly better about identification IF he could age the birds (easy in
> hand, but can be hard in the field). This is where digital helps as we are
> getting better feather detail than ever, so look at the primary coverts in
> particular (but rectrices and other hints can help). One challenge with
> this is primary covert differences are most obvious in spring, some 9
> months after the SY bird was hatched. In the prior fall, these feathers are
> fresher and thus harder to distinguish from fresh ASY primary coverts. In
> the article, I reference an age sex difference in plumages where the
> boldest are the old males and the dullest are the young females (I just
> simplified the heck out of that point!), so Peter's point was that he could
> age the bird and then assess colors and feel good about most IDs.
>
> An area where I was mostly wrong pertains to white in the tail. Years ago
> Peter and I were looking at skins and he showed me a Cassin's with very
> bold white edges to the outer rect, like an ad female BHVI. So, it is
> important to not use the white in the tail as an absolute feature. It is
> still a decent "indicator" and on the extremes still seems safe. Im female
> CAVI show a pale grayish, thin, barely white edge, outside the range of
> BHVI. And, ad male BHVI can have a thick bold edge to such extensive white
> it becomes almost a tail spot, like the former Dendroica warblers (RIP
> those puppies), outside CAVI. Of the hundreds os specimens I reviewed at
> LACMNH, LSU, and the Smithsonian, the differences seemed consistent, so I
> am comfortable there is a trend, but have since learned to add it to the
> list of factors before reaching a conclusion.
>
> It remains a tough ID. Most pictures I am shown from C and S TX of vagrant
> CAVI are either dull BHVI or ones I would not call. I saw a picture taken
> near Park Chalk Bluff not too long ago that looked good, but of course,
> that is getting more west where they are more likely to be more regular.
> Given the overlap in features, and the overlap in ranges, I think it is
> unlikely that we will be able to draw satisfactory lines on maps
> delineating their ranges.
>
> Matt Heindel
> Fair Oaks Ranch, TX
>
>
> On Apr 30, 2013, at 10:41 AM, peter barnes <pbarnes123@xxxxxxxxx> wrote:
>
> > Does anyone have access to a PDF of the 1996 article in Birding by Matt
> > Heindel on separating members of the Solitary Vireo complex? I can't
> locate
> > my copy of that issue. Thanks.
> > Peter Barnes
> > Tyler
> >
> >
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