[birdky] Re: FW: [Fwd: [Va-bird] Black-capped Chickadees in northwestern Virginia (?)]
- From: "Palmer-Ball, Brainard (EPPC OOS KNPC)" <Brainard.Palmer-Ball@xxxxxx>
- To: "BIRDKY" <birdky@xxxxxxxxxxxxx>
- Date: Sat, 8 Dec 2007 10:02:42 -0500
There definitely can be issues with ID of some chickadees; however, not being
near any Black-cap breeding range, we also are not very close to any hybrid
birds from the Appalachians. Also, if anyone recalls the article that several
of us wrote for The Kentucky Warbler after the 1999-2000 irruption of
Black-caps into northeastern KY, it talked in there about how these birds are
probably from far up into Canada and are quite different than both our
Carolinas and any resemblance of a hybrid. The ones that we called and the one
I saw earlier this week were "classic" bird swith very obvious characters.
While we certainly could get a hybrid here in KY, it appears that the
likelihood of getting "good" Black-caps out of Canada in irruption years is
*much* greater. By the way, this year's irruption has been documented by
banding in addition to sight records outside of KY.
The good birds from Canada also sound different; I got a few hints of these
notes from the bird I saw earlier this week, but it was not in the company of
another Black-cap so it was relatively quiet. In past years when multiples have
been present, at least to my ear they have sounded as different as they have
looked.
If anyone is interested in the 2000 article on Black-caps, I have a PDF of the
article I'm happy to email.
bpb, Frankfort
________________________________
From: birdky-bounce@xxxxxxxxxxxxx on behalf of Jackie Elmore
Sent: Fri 12/7/2007 10:18 PM
To: BirdKY BirdKY Listserve
Subject: [birdky] FW: [Fwd: [Va-bird] Black-capped Chickadees in northwestern
Virginia (?)]
With recent sightings in Kentucky, should we consider this?
Jackie B. Elmore
near Stanford, KY
Lincoln County
________________________________
Date: Fri, 7 Dec 2007 14:04:10 -0500
Subject: [Fwd: [Va-bird] Black-capped Chickadees in northwestern
Virginia (?)]
From: marcusb@xxxxxxx
To: carolinabirds@xxxxxxxx
With the apparent southward movement of Black-caps this year, the issue
regarding separation from Carolinas in the field has resurfaced in Virginia, as
noted in the string in VA-BIRD. Another commentary and reference below may be
relevant to the complex situation in the southern Blue Ridge of NC and TN.
M Simpson
Advance, NC
--------------------------------- Original Message
---------------------------------
Subject: [Va-bird] Black-capped Chickadees in northwestern Virginia (?)
From: Birdconsv@xxxxxxx
Date: Tue, November 27, 2007 5:25 pm
To: va-bird@xxxxxxxxxxxxx
------------------------------------------------------------------------------------
Recently, there have been a number of postings concerning sightings of
Black-capped Chickadees in northwestern Virginia and some useful discussion
about how to distinguish them in the field. Unfortunately--and I hate to rain
on the parade--but that region is a documented zone of hybridization between
the subject species and the Carolina Chickadee. Work by Gene Sattler and
associates, most notably the paper published in The Auk in April 2000,*
demonstrate that a principal area of hybridization lies along the ridges that
form the western wall of the northern Shenandoah Valley. Based upon a series of
transects, especially one running northwest from Massanutten Mountain between
Woodstock and Edinburg to a point just northeast of Liberty Furnace, Sattler
and Michael Braun found that..."Genetic data revealed that at least 58% of the
birds in the center of each transect were of mixed ancestry and that
recombinant genotypes predominated among hybrids, demonstrating that hybrids
are fertile." In the case of the transect described above, that center lies
near Columbia Furnace on/near Little North Mountain. Moreover, their work
showed that..."patterns of morphological variation were equivocal regarding
introgression [hybridization] across the hybrid zone." In other words, there
was no useful correlation between appearance--as shown in bird guides--and the
genetic makeup of a given bird. The same situation obtained with song. The
bottom line, in non-scientific language, is that as you can't tell a book by
its cover, in this region you can't ID a chickadee by its appearance and/or
song.
These field studies were carried out during the breeding season, so are
most pertinent for that period. There is strong reason to believe that pure
Black-capped Chickadees do drift south or downslope into northwestern Virginia
in the winter as do siskins, Purple Finches, Red-breasted Nuthatches, and other
"winter birds." Accordingly, some of the chickadees we see in winter in that
area--and which look like black-caps--probably are indeed black-caps. The
problem is that short of genetic analysis we really can't determine which are
truly black-caps and which are hybrids. Indeed, in that area we face the same
problem with Carolinas, and some of the Carolina-looking birds we see in
northwestern Virginia are likely also hybrids.
My interest in this subject arose because I own property precisely in
the zone of greatest hybridization. That is the site where we participate in
Project Feeder Watch (since 1989) and, more recently, routinely submit data to
eBird. Feeder Watch has provided a "mixed" category since the inception and
eBird has just this fall added both a hybrid and a mix category, both of which
we use all year for lack of a better option. However, if it comes down to a
Life Bird call, it appears that there is no good (or legal) solution.
Based on recent history on this web site, I expect that this
information will probably annoy or even provoke some readers. All I ask is that
you bear in mind that I am only the messenger and have no axe to grind here.
With best regards to all,
Dave Davis
Arlington and Cedar Creek
* Morphometric Variation as an Indicator of Genetic Interactions
between Black-capped and Carolina Chickadees at a Contact Zone in the
Appalachian Mountains. Gene D. Sattler and Michael J. Braun. The Auk
117(2):427-444, 2000.
________________________________
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