"... All large sociable birds make noticeable preparations when about to take wing, and some of these initiating movements have no apparent usefulness so far as rising from the ground or water is concerned. ... It is of great advantage to birds which migrate in flocks, such as geese, to take flight so far as possible simultaneously, and thus range themselves without delay into orderly squadrons. Moreover, the movements serve as a quiet hint of danger to neighbors when a bird sights a suspicious object. They have, in fact, a contagious effect. Large gaggles of geese in which one or other of the birds is constantly initiating flight in this way fly up much more often than small parties."