Thursday, April 14, 2011

Another Big Movement of Birds

Checking radar show another night of big movement in the eastern U.S.. The images below show the build-up of birds moving in Texas but the entire area east of the Great Plains shows lots of birds except near the low pressure system moving through Nebraska and the Dakotas.

I got a couple of comments from my last post I'd like to address. 1) The colors do represent the density of birds present. Green shows more density than blue. These patterns are pretty typical of spring movement.

2) One commenter cautioned about assuming these returns show birds. There have been decades of study done on tracking birds with radar during migration. The patterns we're seeing are literally millions of birds moving north. The suggestion that the images might be due to other atmospheric conditions is possible but the returns are too widespread and too consistent with what we underestand about radar ornithology to write these off to anomolies. A look at the information sites addressing radar ornithology such as Clemson University or this excellent primer by John Idzikowski should clarify how we interpret these radar images.

Long story short - Texas is hopping tonight!


Gail V said...

Very interesting-- have never seen your blog before. We were in TX (McAllen) all of March and saw huge numbers of long tailed grackel/starling like birds who congregated at night and made much "music". Is it possible that I also saw a small "flock" of green herons all lined up on a neighborhood telephone wire? It was a quick sighting.

Minnesota Birdnerd said...

Gail I wouldn't be surprised to find small flocks or clusters of any species at this time of year. On a phone wire would be unusual but I've seen them walking on some pretty thin vegetation so I'm sure they could manage the wire especially if there wasn't much habitat around for them to hide in.