This animated GIF is from a series of Milwaukee Nexrad (radar) images from the night of May 19-20, 2001 representing 48 images from about 8 p.m. to 8 a.m. It was prepared and these notes were written by John Idzikowski. Note the following:
  • the sudden "explosive" effect of migrant take-off or "exodus" as it is called by radar ornithologiests
  • the buildup of detections over the Lake, and
  • the morning concentration of migrants along the lakeshore as birds try to make land after dawn

This night had calm winds and does not represent the heaviest migration of Spring 2001. The deepest reds indicate the most birds - about 500 birds per cubic kilometer. Remember that this radar is intersecting a plane of birds concentrated at a certain altitude at a scanning angle of 0.5 degrees; this explains the ring or "donut" appearance of the image. For example, the height of detections over the Milwaukee shoreline is about 500 meters, and over western Michigan about 2100 meters.

Page Updated 27May2001.  This page has been accessed times.

May 19-20 2001 migration