“The Birds”

August 7, 2008

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Erik Proseus

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No this is not about an Alfred Hitchcock thriller…

Birds, bats, bugs, and all sorts of animated critters can be seen by Doppler radar. One time when it’s particularly interesting to watch the radar loops is when flocks depart from their overnight roosts at sunrise and head out all across the countryside. The resulting radar “echo” takes on the look of an exploding donut (or a pebble being dropping in a pond), expanding in all directions before vanishing. A classic signature is shown in this radar loop, which depicts the sunrise departure of thousands and thousands of birds from their roosts in Reelfoot Lake in Lake County, TN (look near the top of the image by Dyersburg).

Occasionally, this phenomena merges with another natural phenomena – thunderstorms. Birds tend to get upset when their normal roosting patterns are threatened, and apparently thunder and rain is one of those things that upsets them. Witness in the video below the light blues that move south out of Shelby County into DeSoto County (Walls to Hernando) ahead of the thunderstorms that break out over southern Shelby Co. There also appears to be a similar radar signature moving west over Crittenden County (Anthonyville to Jericho), though I think that has more to do with ground clutter appearing in the cool wake of the thunderstorms. Ths southbound echoes, though, I am fairly confident are restless birds headed into northwest MS from their roosting spots in southern and southwest Shelby County. ( I apologize for the quality of this video. To view it more cleanly, click here.)