Fantastic shots - this one in particular! I'd crop it a bit, but the shape of the water and position the bird is in, is just fantastic. Very well captured and quite impressive, that they're able to coordinate their bodies in this way...
It's an interesting one in that on the forums they tell me the A7RIV is far too slow for birds in flight. Some have issues and I don't, but then I also use different settings. I would get around 85% - 90% with the AF and for me it seems fast. I only own one AF lens and that's the 200-600. The rest are all manual focus teles and that's where it's taught me other things bedsides AF. Nothing beats the feel of MF.
So I'm a bit weird I guess. The A1 wasn't out when the A7RIV came out and I wanted the 61mp sensor for the cropping. AF was much better than what I thought it would be, but a lot of that comes down to the settings and I use different settings to most out there. If the AF wasn't up to scratch I would just plant on the MF teles anyway.
Very nice shots! I remember trying to capture a couple of special night sky events as well, but I wasn‘t ever well prepared, so results were less than impressive… didn‘t lessen my fascination for things happening in space though.