It looks like Bald Eagles (Haliaeetus leucocephalus) follow a pre-flight checklist before takeoff. They stretch their wings, crouch down and lean forward, and then they fully extend their wings and push off with their legs.
I spotted this eagle on Monday at Occoquan Bay National Wildlife Refuge. I had been observing it for quite a while when suddenly it looked like it was going to take off. I am not sure exactly what the signs were, but I correctly anticipated its actions and was able to capture this sequence of shots.
Most of the time birds take off so quickly that we don’t know exactly how they did it—one second they are in a tree and the next second they are in the air. It was nice to be able to get a sense of the process that a bird goes through as it takes off. As I have seen with ducks, however, the process varies by species and is probably affected by factors such as the weight of the bird and the length of their wings.
© Michael Q. Powell. All rights reserved.
Mike Powell 
Nice Mike! Yes I have noticed that also.
You can almost imagine the cockpit to tower conversation 🙂