Photographing these small birds in flight at close distance presents many of the same problems as with Robins. An estimated fixed focal distance is necessary, while a fast shutter speed and flash are needed to freeze the action of flight.
If Nuthatches are coming to feeders quite often, set up a suitable old worn branch near the feeder on which they, and other birds, will often perch before flying on to feed. Autofocus is fine on such occasions, but it is necessary to make sure the eye of the bird is sharply in focus. I nearly always use spot focusing for such shots. Adjusting the appropriate depth of field is important, so that as much as possible of the bird is in focus, while the background is blurred.
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