My best advice for capturing birds in flight, is practice, practice, practice. Start with larger slower moving birds like Great Blue Herons, Turkey Vultures, and Gulls. Use fast shutter speeds: 1/1250 and faster. Setup 'back button auto focus' on your camera, and choose the AF settings that you like. I prefer one-shot single point, but that is not typical, and you may prefer the AI Servo multi-point method that is usually recommended. Over time you'll also discover if the continuous shooting mode (burst mode) works best for you, or not.
Awesome, thank you for the advice. Some of this info i remember from my studies on the subject, but it is great to have a refresher. There are many new techniques you are throwing up for me to use, and I really appreciate the advice. I was wondering what lens you are using to capture such close ups of the birds. I currently have a 300mm lens, but sadly I can't ever seem to get close enough to a bird. They usually storm off. I know patience and practice!
I use a canon 400mm f5.6 L lens. This lens produces very sharp images, so I am able to crop my shots without losing too much image quality. I also spend a lot of time practicing with my Post Processing software. This helps me in producing sharp images from heavily cropped shots.