Dude don't use digital zoom ! Just max out optical zoom and then merely crop the picture using an image editor. You will get the same effect as digital zoom.
But technicalities aside thats a nice shot ! I have tried shooting eagles with 10x zoom and I haven't got one decent shot. (Mostly because I don't have IS and the picture shakes more than that when I had malaria !)
If you hadn't mentioned digital zoom, I would have assumed you had shot at 3x zoom and simply cropped the image since it is harder to shoot a good snap when the picture is dancing all around.