They do come around despite the banjo. Most humans won't even do that. And they come & stand in the middle of the jam looking at us all.
One day they launched a mission to inspect the stand-up bass. It sounds funny when ducks nibble on strings. They ran, too, when they get a good note out of it.
My bird feeders are all near the porch & during practice they are full of finches & a even a bluebird the other day. There was a line to use the feeder during last practice, and 2 weeks ago a bunch of deer came & stood in the big field & watched us play. I think it is something about music soothing wild beasts...
Maybe everyone should try playing bluegrass for their ducks, too.