'all I can think of is what an amazing thing a feather is.'
I wonder if they reduce turbulence in the airstream like the wing tips on modern aircraft? I see them on gliding birds as well as ducks and geese - Tibetan lammergeiers and the like. Must give more feel for what is happening, in any case.
I got within 20 metres of two giant vultures last month, telyt, you would have loved it. These and bar-headed geese are among the ones that hold the highest flight records. Huge wingspan, our driver honked his horn at them, so they took off. They looked like goats, around that size.