Thanks David. Those images were taken with a D7000 as you will have seen, but of course the methodology would be identical with the D800 which I have. In fact yesterday I captured the attached with the D800 and the D800 is amazing for both dynamic range and the sharpness, but subtle tones of the result. This was taken incidentally in DX crop mode, a setting shunned by many FX users who prefer to just crop. In this shot I used single point AF and panned handheld, normally I would use as you do 9 point and that was the case with my hawk image. When using the D800 for photographing BIF I use DX crop mode because I find I can concentrate more on the subject using the smaller viewfinder area. That's just me though.
I always set around -0.33 to -0.7 EV especially when photographing white birds such as Egrets, Gulls, Swans etc where the white can easily have their highlights blown. It is a credit to the D800 that in fact apart from a gentle tonal adjustment no other changes were made to this as shot image.
Nikon D800 - 300mm f4 1/1000 A f6.3 ISO200 with -0.33EV.