[CT Birds] day migration

David F Provencher david.f.provencher at dom.com
Thu Sep 24 14:03:49 EDT 2009


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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