Great that you are getting Tern shots with fish in their beaks. Nice and sharp and I like the wing position too. The major downfall is that a large percentage of the bird is shaded. Do they dip down lower while coming thru this flight path? Maybe watch them for a while and try to position yourself in a spot that they might drop down lower so you can get some more even light on them. Looks like you have a good spot and they are close enough and have fish to boot. Good luck and keep trying.
Good job by David with the critique, and some nice tips too. Well exposed for what you had, and sharp as posted. I like that the tern is angled towards you.