[CT Birds] Fw: day migration

Carrier Graphics carriergraphics at sbcglobal.net
Thu Sep 24 22:13:57 EDT 2009





----- Forwarded Message ----
From: Carrier Graphics <carriergraphics at sbcglobal.net>
To: David F Provencher <david.f.provencher at dom.com>
Sent: Thursday, September 24, 2009 10:10:49 PM
Subject: Re: day migration


Hi Dave

May I ask another question that might be a part of what I saw. These birds were not just leap frogging from one point to another, they were seen to be putting up from their high point of trees at 1,000 feet and continually flying up to a height of another 1,000 plus feet going due west over very suitable feeding areas of forest and trees below. This leads me to believe their intentions were to make progress on their migration south. Maybe at the time of 9 to 11, we can assume these birds after putting down at dawn have fed enough to give them enough energy to continue their migration, yes?

Sorry Dave, but I seem to have a want to know more about what I saw, and I believe you are surely the one to ask........

Thanks, Paul




________________________________
From: David F Provencher <david.f.provencher at dom.com>
To: Carrier Graphics <carriergraphics at sbcglobal.net>
Cc: "ctbirds at lists.ctbirding.org" <ctbirds at lists.ctbirding.org>
Sent: Thursday, September 24, 2009 2:03:49 PM
Subject: RE: day migration

 
My pleasure Paul. Yes, in fact most warblers do morning flight. It is somewhat difficult to detect unless there are topographical features that cause a concentrating affect, such as Bluff Point. The original discovery was noted at a New York hawkwatch hilltop if I recall correctly (and I may not). As for passerines flying at night it is mainly to use the stable cool atmosphere of night-time rather than a predator avoidance strategy. The stable cool atmosphere makes flying physically much more efficient as well as helping to reduce moisture loss during the long flight period. Songbird migration is truly an evolutionary miracle.
 
Dave
 
From:Carrier Graphics [mailto:carriergraphics at sbcglobal.net] 
Sent: Thursday, September 24, 2009 1:50 PM
To: David F Provencher (Generation - 4)
Cc: ctbirds at lists.ctbirding.org
Subject: day migration
 
    Thanks Dave for your interesting facts. So we then can assume that some warblers might make an additional hr or two further migration after setting down in the early morning to feed? Maybe that's why I saw them going up continually after nine?

I also thought that many small passerines didn't fly in the day because they would be in fact food for the day flying predators. Plus warblers, unlike say swallows, do not feed generally on the wing, so they need to feed from the trees and foliage during the day, and fly at night for protection? 

Paul Carrier



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