All that I can say is that I tried just about anything I could of think of or read. @CntryBoy777 , suggests what appear to be the only viable solutions. For me (flying performing Birmingham rollers) complete lockdown was not viable, and as for the second solution irrational as it may be, I am not inclined to commit a federal offense. The hawks put me out of business. I got rid of all of my pigeons.
With chickens I would go with total enclosure and monitored free ranging or accept that I would lose some birds. They will go for the smaller birds first, but I have had Cooper's hawks attack large fowl.
I've got the predators here too. One tried to grab a pullet earlier in the summer, but it wasn't able to get a good grasp before she leapt into a shrub. I try to be in the yard and visible when they are out free ranging, but it's not always possible.
There has been a large bird hanging out the past few days. I can't see well enough to tell exactly what it is, but thinking prarie falcon or harrier. My friend said she thought red tailed hawk, but it didn't look like any red tail I've seen before. Whenever I get the binoculars out it takes off.
I have been keeping my flock penned up on days I know it's around and chaperoning them when possible.