Well it's still hard to say if they deter the hawks for sure but they spin with the wind very well like I intended. So they are working in that sense. I may either get more or also hang some cds in the trees
I decided to try out some flashy pinwheels to deter hawks. After reading about using CDs and flash tape, I couldn't help buy think of pinwheels. They were super cheap too, we'll see how long they last. A hawk did fly low and move on, but it might have been because the chickens were under a tree...