That 12mm lens must be practically touching the wings! I don't think it is cropped too much.
Damn... I have a hard enough time getting close enough to shoot a bird with a 180mm! Perhaps he camouflaged the camera and set out some food to lure them the bird in front of the lens, then used some kind of remote cable to trip the shutter (...yet another item added to my list of shots to try some day....).