For me one of the most difficult aspects of bird photography is what to do about eyes that are hardly visible in an image that otherwise might be quite pleasing. You usually need a good view of those eyes - preferably with a catchlight - for the image to really engage the viewer. Sometimes it's a dark eye that merges with a black cap, or often with birds of prey it's hooded below the bird's brow and in shadow. What techniques to you use (or not use) in taking the shot (lighting, flash, underexposure, selective focus...) and/or in PP (selective enhancement of lighting, adding catchlight, dealing with "steel eye" from flash, cloning an eye from another image (the horror!)…?
Discussion and suggestions are welcome, illustrations even more so!