Light is quite at a premium early in the morning, so start off with as high an ISO as possible. With dSLRs, you can safely go to 1600. Having a high ISO helps get a high enough shutter speed in low light conditions. As the day progresses, decrease ISO to 400 and subsequently to as low as possible to reduce noise. You can learn more about ISO by reading What Does ISO Stand For?
Shooting fast moving birds, especially at a close range, requires very high shutter speeds in the range of 1/2000 or less. It's preferable to shoot at high shutter speeds for even static animals, as the slightest of blurs can ruin a shot. A general rule is to use a shutter speed at least that of the effective focal length of your lens. Means if you're shooting at 300mm using a camera with a crop factor of 1.6x (most Canon dSLRs), your minimum shutter speed should be 1/480. Again, keep wide apertures to enable a high shutter speed as well as blur the background.