Jim - Very funny "bird chatter"
I had the same problem.
Found the guilty floorboards had spots where the cloth tape had chaffed through so the surfaces were wood-to-wood.
I replaced worn tape where needed. Then gave all edges a good brushing to get rid of grit. Finally, dressed the tape with paraffin wax.
To do that: you can find paraffin wax at hardware or grocery store. (Don't use an old candle - that wax is too hard.) Dip a bar of the wax in warm water until just slightly soft, not melted, then rub softened wax along all the taped floorboard edges. You'll need to re-soften the wax a few times as you go.
I had great results and have had no bird chatter for the last two driving seasons. Good luck.