This is a Foster's Tern I believe, who came across my shooting path when I was looking for some waterfowl. It could be a Common, but Sibley's says Foster's have a white tail with gray border, which I believe fits this bird.
I had it exposed pretty well in camera but struggled to get separation between the eye and black crown in post.
Anyway, I was able to bring some details out of the white. A slightly yellow right wing and underbelly were present in the RAW and I think evidence of the sunrise light.
D850
Sigma 500mm
HH
ISO 4000
1/3200
f4
In hindsight I would've dropped a stop of SS and reduced ISO.
Brian,
I think birds in the sky are a really tough exposure almost always, and are
usually not that interesting to me.
It is most likely exposure I think, especially in not good light.
iso4000 for a sky shot is a lot....