[CT Birds] Big Jan 13 results, a bit of a rant on a snowy day

David Provencher davidprovencher at sbcglobal.net
Fri Feb 8 16:59:00 EST 2013

Okay, time for an indulgent rant! I think using bill size as an indicator
for separating CT wintering Nelson's and Sharp-tailed is not necessarily
wise. There is overlap in length between the northern coastal forms, with
Salt-marsh only averaging longer, Some Nelson's (cauducutus race) have
longer bills than some Sharp-tailed (subvitgatus race). Certainly interior
Nelson's (nelsonii) has a distinctly shorter bill, but this bird is clearly
not the interior form of Nelson's, which I have seen breeding in Manitoba in
June and wintering in CT in January (Great Marsh Old Saybrook by kayak) and
which has a pretty distinctive plumage.

It should also be noted that the bird was not solitary but part of a group
of four observed, I am told. Statistically, a visually distinct hybrid is
unlikely (but of course possible), and it is even more mathematically
unlikely that the one "hybrid" in a group of four birds is the one that gets
photographed. I often think the hybrid card gets tossed a little too easily
when an argument over a bird's id crops up. Many hybrids are visually not
detectable. A final grumpy point, (and maybe it's the Irish in me or maybe
it was the 11 mile hike in the slick snow today making me grumpy) I bridle a
bit at statements of finality, such as stating it must be this "thing" so we
should all just accept that and move on.

Our understanding of just what is meant by the terms "species" and "hybrid"
is evolving, and in a way that doesn't work well for birders in many
instances. Listing birders like to be able to identify a sighting to
species, so they can "count" the bird. Very understandable, very human. We
like certainty, and are uneasy with uncertainty. However the genetic make-up
of many closely related species show evidence of hybridization even in
specimens that strongly resemble the type specimen of only one of the parent
species (often cited as conclusively resembling that species, and therefore
"conclusively" that species). I wonder how many Gray-cheeked Thrushes in CT
have we gotten wrong? Hmmmmm? We used to consider Neanderthals and "Modern
Man" as separate species, and that Modern Man hated Neanderthals and most
likely out competed them or killed them off. Now we know the prime cause for
their demise is more likely that Neanderthals were absorbed into us through
interbreeding (so much for hate!), and that many of us today (but not all)
have DNA components in us which is suspected of originating in Neanderthal
DNA. So I cringe at throwing the hybrid word with finality on this bird, as
that is just a different attempt at identification. Though I strongly favor
Salt-marsh Sparrow as the species of the bird photographed, I'm just as
happy to call this only to genus since it does not represent an
ornithologically significant sighting for the state or region. Many of the
individuals of species pairs we see and confidently "count" might likely
show less certain identifications if we could test their DNA. Another aspect
of "The more you know, the more you realize how little you do know."


Dave Provencher

Naturally New England
-----Original Message-----
From: CTBirds [mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of Mark
Sent: Thursday, February 07, 2013 10:47 PM
To: CTbird
Subject: Re: [CT Birds] Big January 2013 results

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