I played it only in R hand. We just did the opera last weekend.
I practiced the BS (Bird Song) forever with short long short…long short long….fast slow fast, etc.
I practiced with the Philadelphia Orch and Pavarati CD (around 60), but ours may have been faster. I KNOW the other section of it was faster…the one that comes in after that middle stuff.
The only way I could keep up (and not super cleanly) was by greasing. Carmex works really great on fingers …yeah, I know it says for cold sores…but look at the price, $1, and look at the ingredients…great stuff. It starts out pretty greasy, but the greasiness kind of goes away fast. So I greased up before that section and slid on thru.