July 10, 2010 - camping. This photo was taken after an intense storm in the general vicinity of the South Dakota Badlands. I was photographing two rainbows on the horizon. The anomaly in this photo was only discovered after returning home and viewing my photos. My first thought was that it was "just a bird," however it would have been flying headlong into 30 to 40 mile per hour winds; further, the shutter speed was fast enough that the grass in the foreground is not blurred in the winds that were occurring, however the object in the frame is blurred significantly. Finally, and most importantly, what would probably be viewed as the bird's head is obscured by the rainbow which is all the way on the horizon.
Update-- William C. Treurniet has written an analysis of the image.