[CT Birds] day warbler migration?
Kathy Van Der Aue
kvda at optonline.net
Thu Sep 24 19:38:54 EDT 2009
I always thought morning flight was simply a matter of the bird being
exhausted, resting a bit, and flying further after a couple of hours rest.
They would do short hop to find a good spot to relax and tank up foodwise
for the next leg. BTW, today at Birdcraft Museum in Fairfield we banded a
hatch year yellow-breasted chat!
Kathy Van Der Aue, Southport, CT
kvda at optonline.net
----- Original Message -----
From: "David F Provencher" <david.f.provencher at dom.com>
To: "Glenn Williams" <gswilliams9 at yahoo.com>; "CTBirds"
<ctbirds at lists.ctbirding.org>
Sent: Thursday, September 24, 2009 2:38 PM
Subject: Re: [CT Birds] day warbler migration?
> Glenn, Zugunruhe (migratory restlessness) is a complex phenomenon and is
> now believed to occur to a much lesser degree in non-migratory birds as
> well as in other migratory and non-migratory organisms. One could almost
> wonder about humans "Spring Cleaning" no?! This "unquiet or restlessness"
> might be better tied to the hormonal changes and reproductive process than
> directly to the evolved migratory strategy, I don't know. I can't pretend
> to be an expert but the restlessness and the orientation may well be two
> separate mechanisms. I don't know if any real attempt has been made to
> detect increased restlessness at first light during the migratory period
> but it is an interesting question. While the restlessness is known to be
> accentuated by the occurrence of nightfall during the migratory period
> (which occurs of course due to length-of-daylight induced physical changes
> in the birds themselves), the geographic orientation and direction of
> movement of the birds is due to cues such as
> position of the sun, stars, and the orientation of the bird to the earth's
> magnetic field. Of course the magnetic field undergoes a polar swap every
> so often and indeed is undergoing changes now. What that means for
> migration (and the field is slowly weakening as well) in the future is
> just one more question in a multitude of questions concerning the future
> of our little blue rock.
> -----Original Message-----
> From: Glenn Williams [mailto:gswilliams9 at yahoo.com]
> Sent: Thursday, September 24, 2009 2:01 PM
> To: CTBirds; David F Provencher (Generation - 4)
> Subject: Re: [CT Birds] day warbler migration?
> Does any of the research about zugunruhe or "migratory restlessness" show
> that this desire to move in the appropriate migratory direction occurs to
> some degree in the day as well as night in nocturnal migrants?
> Glenn Williams
> Mystic, CT
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