A bird’s conception of manners

If birds have no conception of manners, how does it happen that half a dozen Cedar Wax­wings, sitting close together on a limb–which they often do–will pass a cherry along from one to another, down to the end of the line and back again, none of the birds making the slightest attempt to eat even part of the fruit? This little episode has been witnessed and re­ported by more than one thoroughly responsible observer of birds. What does it mean? If not politeness and generosity, then what?