I tried running the fishing line and also added bright surveyor's tape to make it more visible. The Redtail Hawk was amazingly nimble and got through the lines and killed 2 of my chickens. It was almost mechanical-like. I was amazed. So, now, I purchased 25' x 50' netting. I'll be putting that up soon, once the snow melts. I'll let you know how it works out.
I'm curious - how far apart did you have the fishing lines? I have mature pines in my run, and can't use netting in that area, just where there is clear space. Haven't had a hawk problem, but have lost hens to great horned owls. Losses occurred even though there is a construction trailer turned coop that they can run under easily, in addition to the pines and brambles in the run.