Birds... Fast Birds... Focus Help Needed w/7D 70-200 f2.8 USM IS II

It is very difficult and takes a lot of practice. I'm not very good at it either, but I enjoy the learning process.

One element that seems important, is to be able to anticipate the flight path. I understand good BiF photographers scout possible sites and the various approaches used by birds. I haven't tried this yet, but it appears some birds have a somewhat fixed approach making it easy to pick them up in flight.

If you really want to learn BiF photography, maybe the wildlife forum here will provide more feedback, or else a specialized forum/website. I'm looking at a Dutch birders forum (I'm from the Netherlands) but I'm sure there are some really good international sites as well.