UPDATE: I spotted a hummingbird from a long way off. Take a look at the uncropped and cropped photos. Not bad. Remember this is with a D810 and the 200-500, handheld.
Yesterday the Nikkor 200-500mm f5.6E arrived and it seems like suddenly all the critters in the backyard disappeared! There will be a lot of experimenting to get used to it and find the best settings for various situations. I started this morning with a few shots of the dog and then, through a window, I managed to get this squirrel with a nut in its mouth running across the yard. So, early trials but it is a very solid lens and a great value.