tell you what I saw and it is pure Boudreaux engineering but it did work.
guy took one of those motion sensors and connected it to a horn and when the birds flew in the horn ran em out.
that and he chicken wired all the openings everywhere he could.
before he discovered this little "trick" he tried hanging a rope across the shed and a tarp to make an umbrella over the boat but it didn't last long before it had so much poop it sagged and started dropping patties of poop in the boat
he got the idea of the horn from watching crawfish guys on tv with cannons to chase the birds off and figured he could do that to so he figured out a way with a motion sensor pointed up into the rafters so it doesn't go off when you move around, 12 volt transformer, and car horn mounted up high where the birds nest
I suppose you could use a sprinkler system instead of a horn if the noise would bring complaints