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Nocturnal Migration April 24, 2012

posted by Tim Avery at
on Tuesday, April 24, 2012 

Last night was another superb night of migration over northern Utah.  The favorable conditions certainly are lending a hand to keeping things moving.  As I ogled the radar last night it was awesome to watch the stream of birds leaving the north end of the Great Salt Lake and heading off into Idaho.  Large numbers of birds in the 20-25 dBz level could be seen rising then heading north and dispersing.  Based off the density it is presumed that there are approximately 200-600 birds per km cubed where it reaches this amount of reflectivity. (via Clemson BirdRad).

I have put together an animation that starts at 9:00pm last night and lasts 90 minutes.  Check it out:

Just watch for the green to appear around 3:24 UTC and move northward till it blends into the blue around 4:02 UTC.  Pretty cool to see that high density of birds as they move north from the lake and north end of the Wasatch.

I expect there to be a fair number of new shorebird arrivals today given the movements last night.  Plus it's about time for some of the big waves of Yellow-rumped Warblers to be coming through as well.  Yesterday I had my first Yellow Warbler of the year as well as a Lazuli Bunting.  Reports of Bullock's Oriole, Thrushes, and other migrants have also been coming in.

Interestingly last night, I saw what was one of the coolest radar images I can remember.  It was the showing the entire US, and what was cool/odd about it was the fact that the Midwest was exploding with migrants, while the east half of the country looked just like the west half with very little showing up on the radar:

Typically this time of year the entire east looks like the Midwest, but last night migration in the east came to a crawling stop.  This could be in relation to the storm that passed through, but I'm not sure if that is the whole story seeing that everywhere from Florida norther to Maine, and the Carolina's west to Missouri were all effected.  In any event it made for a rather cool radar image--that makes me wish I were birding in Texas today!

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