Thank you, Shirley. There is lots of emphasis on the front focus here, which takes in the head sufficiently but not much else. I think this is OK, 'though. More dof is not a reasonable option given the high shutter speed required for these little birds.
Thank you for your comment, Gene. I agree that white feathers are a problem. How I solve it, is by dialing in exposure compensation (negative.) The amount depends on the camera, lighting conditions and the nature of the subject. Usually I try to make a test shot if there is opportunity, or just make a good guess on basis of past experience. When photographing birds, I shoot in aperture priority or in manual mode with auto iso. Of course, you have to keep an eye on the shutter speed in any case.