I understand if you hang reflective aluminum pie tins and old CDs that spin and flash, it will confuse the hawks and they'll leave. I looked for a good reference but couldn't find one. Anyway, it might be worth a shot.
I know of people that do hang reflective stuff. They have not lost any chickens to hawks. It can't hurt. It also helps to have hiding places. I took a large piece of scape plywood, put 4 half sides on it and turned it so that they had a hiding place with plenty of escape. With the Harrison Hawk, hunting in packs it I'll not always work. When one goes in on the ground and they leave the other ones will pick her off. But if they are spotted early enough it works great. Chickens usually are very alert the sky predictors, and if you have a good gentleman rooster it is his job to spot threats and sound the alarm.
SnowOwwhitch is might answer your question on fishing line. Where I used to live, that is at my house, I had 1 family of Harrison Hawks overlapping the territory of a white tail hawk, there were a lot of alarms going off for some time. Then it's lowered down. I have a T-Frame garden set up, with baling twine as a trills, then bird netting over that to keep the girls out. I found what I believe to be hawk feathers. What I think happened is a hawk came in between the trills and got caught in the bird netting. My girls have dedicated to finding ways into my garden. Two of my girls where happily eating my garden inside the raised bed. They were already in the garden or ducked in for safety, but after that my girls have had a much more peaceful time free ranging.

As for my garden, it remand in danger from the girls. Hawks were my house is are way to hungry to wast time when there are so many golf courses and fat Bunnies
you can see the netting. I bought 14'X300' at a ag/greenhouse sight.
. I lifted the netting so my girls could clean out my garden bed, plants and bugs/grubs.
Correction: you can see the netting here too. I tied to bottom to PVC pipes I lifted 1 section.
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