Lots of great info on here. Some not so good cause it is just brainstorming without knowing much.
Summary: these are starlings and sparrows.
not smart as crows. Starlings taste bad to raptors, (except when they are babies taste good). Sparrows taste good though to raptors. Raptor hunting with a paid falconer would be expensive and would not last long. Introducing raptors would not work, not likely to stay.
can't teach starlings to stay away by killing or torturing one of them like u could do with crows, or geese either. Distress screeching will actually call in starlings to investigate, then they will forget about the event anyway (not like a crow)
noises, predator decoys only last a little while till they get used to it.
Thinning or reducing trees doesn't work if they already are there in big numbers.
They aren't nesting, nor will they ever nest in groups (starlings). They are roosting. Gathering in big numbers for protection.
Cutting the trees down used to be the only solution that worked before and this is what I thought u would have to do. BUT this sprinkler or mist system sounds promising and several of u said it works, so that's cool, I learned something.