[CT Birds] day warbler migration?
David F Provencher
david.f.provencher at dom.com
Thu Sep 24 12:47:26 EDT 2009
Paul what you were seeing is called "Morning Flight." I only have a moment or two so here is a brief description: It was discovered many years ago that nocturnal migrants (not all but many) do a brief period of continued migration in the early daylight hours. This the big push that happens at Bluff Point that you hear about in postings. I happened onto the concentration that occurs there years ago but I don't have time in this post to discuss the nuts and bolts. Suffice it to say that the nocturnal migrants come down to rest in the predawn. Then shortly after dawn they start moving again, hence "Morning flight." While nocturnal migration tends to be "Broad-front migration" or generally by compass heading, morning flight tends to be more "Leading Edge" migration, following ridgelines, coastlines, river valleys, etc. So what you saw were indeed Morning Flight migrants (well spotted by the way!) They will push on for about 1 to 2 hours then settle into foraging then resting by mid-day or early afternoon. Not all species do it, for instance Warbling Vireos are believed to largely not undertake morning flight. I will try and do a more detailed discussion post later this week or weekend but no promises since I plan to be hiking in the White Mountains on Saturday!
To me, I felt these birds were doing a true migration during the day! We all know most passerines migrate during the night, but has it ever been seen that Warblers might just do some migration during the day hours?
Would be interested in hearing any comment to this........
Naturally New England<http://naturallynewengland.blogspot.com/>
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