the breed defiantly has something to do with it. i want to know the breed because i want to know the size of the chicken. if the chickens is a very large chicken than hawks won't attack the chicken, hawks tend to go for smaller breeds of chickens. if you don't believe me than look it up.
To a certain extent I agree with this. Previously I had lost chickens to hawks When we started a new flock again several years ago I wanted something big, so I got Jersey giants then added a few other large birds. We actually saw hawks come down and sit in trees, but not attack.
Twice I witnessed unsuccessful hawk attacks. In one case the hawk was after a small Easter egger who was able to dive under the deck and another time the hawk went after a less than three month old juvenile who scooted under an evergreen. We have lots of shrubbery and hiding places for chickens.
I know of a successful hawk attack recently with someone else. The hawk got the smallest chicken in the flock.
There are many small flocks in our area and the consensus seems to be if the chickens are out for example in a pasture, with other animals like horses, goats or sheep, the hawks won't come down. They seem to be aware of what they can and can't carry away, and won't come down if the prey is too large to carry.
Recently this past winter I was out with someone else and we both had dogs on leashes. A hawk swooped into a tree, only about ten feet away right between us and with barely a pause flew off carrying a squirrel which had been running up the trunk of the tree.