Weather Radar and Migrating Birds

We are fascinated by how, when and why all birds move at The Raptor Center.  One interesting place to find information is NEXRAD radar, which one can monitor using CONUS loops.  Looking at the velocity and reflectivity images, we can actually "see" densities of migrating birds at night!  Weather patterns of south winds or precipitation, for example, might mean birds will not move into that front.  However, one can "watch" many birds (mainly songbirds and shorebirds) all "rise" late evening/early morning to migrate in the cooler air, and "fall" back onto land in the early morning hours.  Here is a page of FAQ and some defintions.  Fall and spring are very active times for many birds, as they either travel to or from breeding grounds.