Date: 3/13/17 5:16 am
From: Dnadeb <dsg4...>
Subject: Re: Allegheny County - Chickadees
Good observation. A couple of years ago Robert Curry from Villanova spoke about his research on this very topic. With Carolinas moving north the interbreed sings nearly exclusively the CACH song. You are correct. Birders can be more observant as this moves across the state. We have not noticed it yet in Central PA.
https://www1.villanova.edu/villanova/media/pressreleases/2014/0307-1.html

Deb Grove

Sent from my iPhone

> On Mar 13, 2017, at 1:20 AM, Sameer Apte <sameerapte1...> wrote:
>
> This afternoon, Aidan Place, Jack Chaillet, and I birded North Park, where
> we searched for Black-capped Chickadee (which Jack and I needed for our
> county year lists). Despite the many reports of exclusively BCCH at this
> location, every chickadee we found either resembled a pure Carolina or
> predominantly resembled Carolina in phenotype. One chickadee at lake
> elevation (970') had extensive white on the tertials and on the cheek
> patch, and several chickadees at the Latodami Nature Center (1110') were
> clear phenotypic hybrids between Black-capped and Carolina. Although we
> heard many Carolina songs, we did not hear a single Black-capped song, and
> many of the hybrids certainly appeared to be possible backcrosses with
> Carolina Chickadees.
>
> With BCCH reaching their furthest range southward around this time of year,
> it begs the question as to why almost every chickadee seen in North Park is
> identified as BCCH on eBird. Are most of these reports are from a higher
> elevation, where pure Black-cappeds are certainly plausible? Are Carolinas
> (which are expanding northward) being dismissed as the traditional species
> of Black-capped at this particular location and in other places north of
> the Allegheny River (which I believe has been the demarcation line for the
> last fifteen years or so)? Or was our sighting just highly unlikely and
> exceptional?
>
> I'd love to hear thoughts and experiences from people in the Pittsburgh
> metro area about this paradox -- it seems like chickadee identification is
> a thing that comes up once in a while, but maybe not as much as it should
> in an area smack dab in the middle (or maybe not anymore) of the
> hybridization zone. Perhaps it would be constructive to conduct a sort of
> informal census of areas north of the Allegheny River to determine the
> current demarcation line and hybrid zone of this species in the area.
>
> And if anyone has any clue what exactly those mutt chickadees in North Park
> really are, please let me know.
>
> Thanks and good birding,
> Sameer Apte
 
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