Beautiful Swallow shots and great colours. Nice clear shots and good details showing.
I agree with Mike, they need more room. I always try and give more room in front of the bird and below it. I know a lot of people like to crop tight so the bird ends up larger in the frame, but that's also a trap visually often. If you have the room in the crop, just give a little more space and avoid those tails being slightly cut off . That -.03 EV shouldn't make a great deal of difference if you are shooting RAW.
All the best and still fine shots anyway.
Danny.