Kingfisher Flight

I often see this Kingfisher in the same bend of the Clearwater River near my home in Idaho, in a clump of trees over a wide smooth stretch of water. It would often flit from one end of the trees to the other just a few feet above the water surface, so I got halfway and waited. I wanted an image that conveyed movement, so I set the shutter speed low and panned as it flew by, which blurred the chunks of ice floating in the river as well as the bird. What surprised me about the image is how the Kingfisher is both sharp and blurred at the same time. I'm interested in feedback.

Canon 5d Mark iii, 300mm f/2.8 lens w/1.4X teleconverter, 1/20 sec at f/16, ISO 200