I guessing this is a pretty tight crop because the sharpeness just isn't there in the feathering. I an guessing you shot pretty wide open and at a ISO 400 at least. Something is funny with the lighting too.
Show me the original shot and tell me the particulars ( What lens,camera and exif info) and maybe I can help.
Here's a shot on the wing with a bit better detail in the body
The 80-400mm f/4.5 -5.6 lens, on a D200, is painfully slow and in shady or contrasty situations it's been a challenge. This is a new lens and I'm working the kinks out. EXIF: 1/640, f/6.3, 1EV, ISO 800, 400mm. Although the shot won't win any awards I was quite pleased that I was able to get a bead on him at all. I feel I needed a faster shutter speed in order to get that tack sharp image I had hoped for. I've been working with shooting at high ISOs so I can get the faster shutter speeds. However, the light was the light. As you can see from the hand held, un-pp'd, 100% cropped version below those colors came off the camera, that's how we grow 'em down here .
Actually you might get a better pic at a little slower shutter speed and get your lens stopped down to around F/11. F/11 should sharpen it up a good bit and give you a deeper depth of field. I think what's happening here is the shallow depth of field at 400mm is not getting the whole subject in focus. You may need better light or a tripod also .
keep trying combonations.