It is a challenge to photograph flying birds for a panorama. After some practice the success rate goes up (hopefully). Basically you shoot a burst of images as you try to cover the area of birds flying you want. Also panning as you shoot, going in the direction they are flying. I found that shooting with a wide angle lens for a large group of birds flying does not give you as much detail as shooting them with a telephoto lens for a panorama. A pretty high shutter speed is also helpful. You might have a few touch-up areas or overlaps to fix once you assemble the base Panorama.
The panoramas below are a group of Black Skimmers on or close to the shoreline. This is a little easier because most of them are not moving, but again you might need a few touch-ups here or there.