NWS Doppler Radar Detects Birds Leaving Green Island

A large group of birds was detected leaving Green Island on Green Bay to feed just before sunrise on August 10, 2006.  This radar signature, known as a "roost ring," occurs as thousands of birds leave their roost and fly into the air.  The roost ring expands until the birds begin foraging after dispersing. 

Below is an eight-image animation of radar reflectivity from the NWS Green Bay Doppler radar.  The first radar picture is taken at 5:25 AM; the last one about 6:15 AM.  (Animated GIF image.)

Radar animation

Another example of a roost ring from Green Island was documented in August 2010. Click here for more on that event.


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