Something else I learned the other day when I was scooting around the web for more info - not only do I notice their cries, but their kind of strange way of flocking - for instance, Canadian Geese have the arrow straight flying "V", but the cranes seem to kind of wheel around a bit.
Anyway (blah, blah, blah) I guess they play a lot on thermals - hot air (well, warmer air) that rises, hence the slightly random characteristic to their flight.
Well, *I* found it interesting 'cause I've wondered why they stagger around like drunks heading home! Okay, not that bad, but....