Fighting Sparrows on My Dock

I built a 70x30’ covered dock on my bayou place a couple years ago and the sparrows are bad. Nesting, shiting, etc and I’ve harassed them pretty good but they are hard to deter.

I’ve tried fake snakes, which work a bit but you’ve got to keep moving them. I’ve torn down nests and they can rebuild overnight, freaking nuts. Spray with hose everytime I wash down my boat which they don’t like and that’s worked a little. I’m thinking of getting a pellet gun but I don’t want to damage metal roof. They’re an invasive species and I believe legal to kill them.

Does anyone have the silver bullet?