When any BH owner asked for my advice on how minimize those owls or birds of prays attacked I usually will list them all the available methods of getting rid of these predators.
My favorite is the shock wires.
All you need to do is to installed those shock lines on all those areas where these predators will perch.
Connect the positive and negative wire ends to an electric inverter or transformer.
Once those predators perch or touches the two wires they will get a shock of their life.
This method is less harmful to those predators. They will usually stay away from your BH.
There are other additional methods that you can deploy.
One common method is to set some kind of netting around your BH.
You can fix a set of poles to hang those netting.
The net can help you to trap these predators but try not to be too high.
Have a good look at this picture taken a few days back: