It seemed to not be that afraid, soared right over top of me and made two passes. This was after I had followed him across a field. Even at a fairly close distance, the 400mm is not quite enough for a big bird like that, which surprised me.
As I was rather excited to see it, I didn't even think to turn IS off, which was completely unnecessary when I could get 1/1000 at ISO100. This caused me to clip off the end of his wing unfortunately, although through the viewfinder I thought everything was in the frame.
