I'm amazed at some of the suggestions you're getting. This is what I use with my 7D and 400mm 5.6/
I shoot in manual and in raw, always. You're in control of shooting and pp.
In custom function set the 'tracking' to slow, you don't want anything other than you're target to distract the af.
Use centre point with expansion for focussing. You've got a light lens, in my opinion the best for following bif's. It's relatively easy to keep you're subject where you want it.
You can get away with shooting at f5.6 just about all the time and get you're speed up by increasing the iso although if you need to go above 800 iso, pack up and go home.
Set the camera to focus using the back button, it takes some getting used to but it's worth it. You can then leave the af set to AI Servo and forget the One Shot setting for stationary subjects. Then all you have to do is focus on your subject with the back button, keep the shutter half depressed, every so often as you track the bird blip the back button. Then when you're ready, focus and shoot.
Anyone tells you it's easier it's easier to to focus and shoot with the shutter button and get 'keepers', hhmmm, i don't think so but then thats my opinion.