[birdky] FW: [Fwd: [Va-bird] Black-capped Chickadees in northwestern Virginia (?)]

[Jackie Elmore <jackiebelmore@xxxxxxxxxxx>]

 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 -0500Subject: [Fwd: [Va-bird] Black-capped 
Chickadees in northwestern Virginia (?)]From: marcusb@xxxxxxxxx: 
carolinabirds@xxxxxxxxxxxx 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 SimpsonAdvance, 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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• Follow-Ups:
  • [birdky] Re: FW: [Fwd: [Va-bird] Black-capped Chickadees in northwestern Virginia (?)]
    • From: Mark Monroe
  • [birdky] Re: FW: [Fwd: [Va-bird] Black-capped Chickadees in northwestern Virginia (?)]
    • From: Palmer-Ball, Brainard (EPPC OOS KNPC)

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[birdky] Re: FW: [Fwd: [Va-bird] Black-capped Chickadees in northwestern Virginia (?)]