Pre-fledging behaviors...

I am starting to see pre-fledging behaviors now on some nests. Older chicks are flapping their wings and hopping with exuberance. For some reason when I see them flapping, I count the flaps...am getting up over 30 flaps in a row as they build strength in those beautiful long wings. Chicks fledge at about 55 days...males tend to fly sooner than females and there is some difference bird to bird. Nothing hard and set about exactly when they take that leap. It sometimes seems as if a gust of wind takes away a young bird who was only intending to do some flapping...but, like it or not, is suddenly airborne. After 21 years of watching these first flights I have concluded that flying is not that hard, landing is! Sometimes they fly around in loops, as if trying to figure out how the heck to get back to the nest and stop! It often ends with a face plant on the nest. Haven't figured out the brakes. By this time the young birds are almost as large as the adults...do you how to tell them apart?