Get yourself a crow call from hunting store & use when in yard . May make the hawks think there are crows at times ,use one here I fly roller pigeons . Could also get a disc of crow calls & play . But the sure way is to lock um in or cover run . Yu can always take down for winter .
The hawks will be there as long as you keep showing them your birds & they get to eat them . Lockdown in stout pen with good wire sounds like the only thing to do in your case .