I had a really annoying whistle one day - but it was caused by a large dragonfly that got wedged under the windscreen!
Actually, as I recall, it sounded more like I was being chased by a giant dragonfly, as the wings were vibrating in the wind! :mrgreen:
I had to wait till I got home (100 miles or so) to get it out...
Oh, and then there was the one that hit the windscreen... :shock: Yuck.
Kenny