Previous research, under the direction of Dr. Sidney A. Gauthreaux, Jr. at Clemson University, evaluated effectiveness of NEXRAD WSR-88D weather surveillance radar for studying roosting birds.  We subsequently used the WSR-88D to 1) study the pre-migratory roosting behavior of Purple Martins (Progne subis) in South Carolina, and 2) map locations of major Purple Martin roosts across the eastern United States.  Additional information on radar ornithology and Dr. Gauthreaux's ongoing research can be found at the

Clemson University Radar Ornithology Laboratory (CUROL) website.

In the following animation from the early morning of 25 July 1999 at FFC

Atlanta, GA, Purple Martins are leaving roost sites all around the radar.

At least 9 roosts (rings or partial rings) are visible in this series of

 images (several roosts are actually in Alabama): 3 to the south, 3 to

the north, and 3 to the east. Notice the pattern of expansion over the

course of approximately 40 minutes as the martins leave the roost

 sites to forage.