It’s hard to get a good bird portrait. Ideally, such a shot is against a very smooth background and is composed such that the iris is in crystal-sharp focus and there’s a bit of light on the eye. These “catchlights” look very different on living animals than on stuffed or dead ones and helps to psychologically convince the viewer that the animal is healthy. Birds are particularly difficult because they’re constantly preening their feathers, so are in constant movement. Thus, as they move their head, the background changes, the focus changes and many positions cause the catchlight in the eye to go away. Getting a good shot largely involves a mix of luck and patience. Good lenses help, but really, patience overwhelms every other consideration.