[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.
>
> Dave
>
> -----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?
>
> Dave,
>
> 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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