Jan, Frank, I'm glad you like the photo.
Frank, yes, the photo was taken with the Z-Nikkor and the Z teleconverter. I'm very happy with the converter, with the 400 it's still quite a compact 8oomm, even on the Zfc the combination is still usable.
Unfortunately, the chick in this photo was a bit out of focus and I used the ON1 NoNoise plugin to adjust it, so the result is not entirely due to the lens.