Great image, only thing I noticed was my eye tended to be drawn toward the top, toward the blurry branches, and away from the bird. Perhaps a tighter crop, with the bird placed in the upper right?
Picking what to make B&W and what to leave in color is a difficult task, and I think you made a great choice here. In what was probably a very boggy environment that would have made the shot bland you made a great choice to spice the shot with B&W. Way to take what could have been an average shot and turn it into a great shot by seeing it outside the box.