Saturday, October 10, 2009

Millions of Birds on the Move!

Thanks to clear skies and calm or very slight WNW winds, there is a massive southerly movement of birds tonight in the Adirondacks, and indeed throughout much of the eastern half of the country. The image below shows the U.S. Radar Mosaic (from at 8:38 this evening. Here are close-ups the the radar loops out of Colchester, Vermont from and Ft. Drum, NY from
The "starburst" or "donut" of blue and green colors surrounding the radar sites are typical of birds, as opposed to weather. To confirm that these are birds, one can click on the radar image to obtain a velocity image as seen here:and here:

Things are moving from the N and NW (represented by the blues and greens - objects approaching the radar) to the S and SE (represented by yellows and oranges - objects moving away from the radar). This is the expected direction of migrants on a night with calm or northerly winds at this time of year. (Also, the colors on the radar images only appeared after dark, when most birds are migrating.) Therefore, we can conclude that the colors appearing on the radar are mostly, if not all, birds. Step outside in an otherwise quiet area on a night such as tonight and you will surely hear birds passing overhead. See Brian McAllister's August 21 post on the subject of identifying nocturnal migrants by their flight calls :

For more detailed primers on birds and radar see Derek Lovitch's blog at, David La Puma's Woodcreeper site at (and especially, and this Clemson University site:


  1. Glorious. I've seen this presented a few times, but not as thoroughly. It boggles my mind--in a good and hopeful way. Great post.

  2. Wow, this is so neat! Thanks!

  3. Fantastic images. Would be interesting to see this time lapsed over the migratory season to see the successive waves of birds migrating over time.