During our extended bush walk that ended with our best Hihi/Stitchbird encounter, we saw a cluster of Piwakawaka/Fantails hawking insects in the sun at the bush edge. When finding these opportunities it is worth spending a little time as the yield is low. It is always challenging to track the erratic flight and lock focus.
Because the action is so rapid it is impossible to see the moment of interception so you need a good sequence of images to select the peak of the action. Modern mirrorless cameras with subject/eye tracking make this a lot easier than in the past but it is still technically challenging.
I have no idea what I have captured until I get a chance to review images and it is always exciting to see the unseeable frozen into an image. The agility and manoeverability of the birds seems even more amazing when caught as a photo.
Photos with Nikon Z9 and Nikkor Z 400mm f4.5 VR S. I find continuous autofocus set for animal detect, wide-area custom set for almost the full frame works best. Smaller areas are quicker to acquire the subject but Fantails are so erratic that I need more than wide-area-large. Setting wide-area custom to slightly less than the full frame is the best compromise for me between speed and maintaining lock when photographing Fantails or Swallows in flight.