Flying Birds and other fast moving animals can be a challenge to photograph. They can be even that more difficult to get detail in their body as they are running or flying. When photographing almost any kind of wildlife, one of the most important things that you can have is patience. Animals rarely do things on a set schedule, and the ability to be patient and quiet can be a challenge. As soon as some animals know that you are there, they may take off in the other direction faster than they approached.
A reasonably good telephoto lens is almost a must in the camera case. This does necessarily mean that you need to purchase a $2,000 or $3,000 lens if you are not a professional wildlife photographer. There are many rental companies such as Borrowlenses.com that will allow you to rent one of the more expensive lenses for a fraction of the cost that it would take to purchase it. A 70 - 200 mm high quality lens can be rented for 5 to 7 days often for less than $100. Consider a fixed aperture lens of at least F-4 when deciding what lens to choose. A fixed aperture lens will often focus much faster than a variable aperture lens.
When shooting, Aperture priority can often work well, especially when coupled with a small aperture. This will often give you a very fast shutter speed with will be important because you will obviously want your bird (or other animal) is sharp focus when it is moving. The wide open aperture will also limit your depth of field, so that your viewers will focus on the animal, and not what the animal is running/flying past.
You will also want your camera's focus to auto-track your subject. When using cannon cameras, AI servo mode will do its best to keep your subject in focus. You will often have the best luck with this if you use the center focus point squarely on your subject since this point is typically the most accurate.
Set your camera to continuous drive mode. This will let you capture different aspects of your subjects motion as well as radically improve your chances that the subject is focus during one or more of the frames.
Your ISO will obviously vary depending upon whether you are shooting on a cloudy day or bright sunlight. In most cases, you will probably try to keep your ISO under 400 for the sharpest possible image.