Some excellent images, Richard. All nice but I really like the overall images of the wattlebird and honey eater. Very well done.
According to Tom Hogan's review of the 200-500 it does breath significantly. He claims the effective FL at minimum focus distance is more like 400mm. However, regardless of that the specified max reproduction ratio is slightly higher on the 200-500 at .22x versus .18x on the 500 PF....Another thing I have noticed is how close many of the birds are using this lens. I'm guessing the 200-500mm suffers from focus breathing.
I've not noticed this behavior but then again I rarely shoot at minimum focus range. I'll drag mine out and give it a test today when I get a few minutes. The only body I have with me is the D850....The lens would be close to min focus for this shot. Which would make the focus freeze if I was to try and refocus the next shot on a subject in the distance. Refocusing wasn't an issue if the next shot was still in the general vicinity.