Hopefully I can help out a bit.
Firstly, catching birds in flight is quite possibly one of the most difficult and yet rewarding skills to get/have.
You'll really need to track them and take many many shots.
These images are just two, out of a whole bunch of throw-aways.
Use your flash for fill, regardless of the distance between you and the subject. Also, don't worry about blowing out the sky, you may have to push your exposure up by 1 to 2 stops, as your camera's exposure meter will probably be reading the sky, and the bird will actually be underexposed.
As for the bats, about the only way you'll get any kind of image of them, is to set up your gear to capture a certain area/zone. Use a remote cord, and watch that area, when a bat enters it, hit the button. Most of the images you see from photographers getting bats, is where they have actually set up motion detectors along with multiple flash heads set to fire in multiple firings.
Mostly, it takes patience and practice. Just keep at it, and eventually, you'll get the image you really want.
Also, try not the shoot a bird from behind. Bird butt is not the most pleasing image.
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