VA-Birders,
Yes, the article mentioned is very interesting, and it looks like a well-done
piece of research. It is linked below for anyone who might want to read it in
its entirety. It does seem to poke significant holes in the "common knowledge"
that I have been led to believe over the years regarding this ID. Whether it
was based on previous research or just mere speculation, the seeming threshhold
for determining whether a Chickadee was one species or the other was if both
the (all) vocalizations were of one species and all of the respective
morphological characteristics were in place.
http://findarticles.com/p/articles/mi_qa3793/is_200507/ai_n14850667
What I would now be interested in is whether any research has been done
specifically around the occasional observations of each species "out of normal
range". The hybrid zones, as mentioned in the study, have been determined to
be quite narrow (~15 km) and stable. During the winter Black-cappeds are
sometimes found away from their breeding territories in search of food. It can
probably be safely assumed that in non-irruptive years, the birds that appear
in lower elevations are as likely pure Black-cappeds as they are hybrids.
However, I wonder about the individuals that have been reported far away from
the hybrid zone, such as coastally, and even many miles from this zone in the
interior, especially if they are very rarely found in a particular area where
they are suddenly being found. It would be interesting to determine whether
BCCHs banded well inside their normal range have been sighted well away from
this zone, especially during major irruption years such as what we are seeing
now, therefore showing the dispersal of birds from points farther to the north
than the zones. This may be well-known, but I haven't found any solid info on
the subject.
Moreover, I would still think that *apparent* Black-cappeds observed in areas
to the south and east of their expected range should be reported to this
listserve so we can get snapshots of their possible movements. It would seem
that a more responsible method of reporting them might be something like
"Black-capped appearing" but I still believe this information can be useful to
the birding community.
Thanks,
Jay Keller,
Arlington
-----Original Message-----
From: Dave Hewitt <dhewitt@xxxxxxxx>
Sent: Nov 28, 2007 2:18 PM
To: VA-Bird <va-bird@xxxxxxxxxxxxx>
Subject: [Va-bird] Chickadee ID in VA
Thanks to Dave Davis for the excellent post about chickadee ID. The Sattler
and Braun paper is great, and adds weight to a considerable amount of
evidence that appearance and song aren't reliable for IDing chickadees in
the hybrid zone (which, in most places, has a fuzzy boundary).
I can't imagine why anyone would be annoyed or provoked by the evidence in
the paper. It just adds to the common, humble wisdom that sometimes you
can't know. Frees you up to worry about other things. If you're looking for
your lifer Black-capped, take a road trip.
Dave Hewitt
Gloucester, VA
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