I am assuming here that this is a F-mount lens on an adapter and a Z-Mount body?
If so, the combination seems to be working well in your hands.
I have always found getting good shots of small birds to be challenging.
Lovely photographs, Øivind.
Now stop teasing us; what did you buy? 
Thanks Hugh and Ian. OK, while I long had been thinking about a second smaller body to use for wider lenses when my Z8 is in wildlife mode, I had pretty much decided to wait that out as I like my Z8 too much when the Z5 II showed up with a $350 discount at the last Nikon refurbished sale, so almost down to what a new Z5 will be at after the September price increase. Before I knew it I had it in my cart and ordered it.
So not the 45 Mpix and the speed of the Z8 that I have become addicted to, and not the body one would primarily get to capture fast small birds dashing around in the brushes.
It arrived with 28 actuations on it and very clean except for some dust that I blew off the sensor, and I am pleasantly surprised how well it performs thanks to the Exped 7 engine goodies and bird detection. (The squirrel test with animal detection in the August thread had 100% focus success, including the straight frontal view that sometimes tends to front-focus on the nose.) On top of that I used it here in the full electronic silent shutter mode that can cause shutter drag with the slower sensor, but only got one frame where a wing perhaps got a bit more curved than likely in reality, and my framing was off at the right edge of the frame. Of course switching to front curtain electronic shutter would avoid the shutter drag. For wider use the Z7II sensor would perhaps have been more suitable and not cost much more refurbished, but it would not provide the focus performance seen here that makes the Z5 II a good backup to the Z8 in a pinch as long as one does not need to crop too much.
