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What kind of bird is this:  http://www.youtube.com/watch?v=E0dZH-iKz48 ?  I found it on the beach in Pensacola Beach, Fl, and have seen them a few times.  They kind of flop up on the shore and just lay there like they are injured, but they aren't actually sick or injured at all.  Their legs are really far back too.

If anyone can give me some idea of who this bird might be I would really appreciate the help. This bird and I spotted (startled) each other at the same time. He barely touched the branch and took off. I had been photographing sparrows and couldn't focus fast enough to get a good shot of the big guy. The photos are way out of focus so any ideas ...