Watching hummingbirds hover, and fly both backwards and forwards, the supreme master of flight that they clearly are,....
Fuji, You don't know how good it feels as a helicopter pilot to see those words written by a fixed wing pilot!
As for nature's aviators, I could spend hours watching the auks and the fulmars flying to and from their precarious cliff nesting sites. Downwind approaches followed by an impossible turn into wind, flare, stop and land in an instant and as often as not a go around, all with a terrified look on their faces!. It never ceases to amaze me how the Puffin got its license seeing their landing technique - and they do it for a living!