Hawks will usually look their prey from above when circling. They have amazing vision an can even spot a mouse from that high up. Once they find their prey, they will roost on a branch or a telephone pole and watch the prey. Once the hawk believes that it has a good opportunity, it swoops to the prey. In a chickens case, it will generally happen one of two ways. If the chicken is small enough, a young chick or bantam sized, it may carry the prey off. If it is larger it will land either on top of or near the chicken and start eating the chicken on the back and neck area, standing on top of it. There may be other ways this can happen, but this is a generalization of what happens in a hawk attacking a chicken. You can deter hawks only because they are federally protected. Some methods that I have heard that work are hanging CDs or anything that reflects, off of branches and tall areas. Hawks don't like the reflective surface because it obstructs their view. You also should make sure you have a top of some kind on your run (I don't know if you do or not). If you are free ranging, make sure there is plenty of ground cover. A hawk won't typically chase a chicken on the ground into thick bushes and brambles. My chickens alarm when anything flies over (helicopters included

) and will all hide in the bushes. I've noticed my rooster is very good at looking for hawks. If you don't mind crows, you can find a way to bring them into your property. Hawks and crows do not like each other and crows will run hawks off occasionally. I have not lost to a hawk yet, using a mixture of these methods.