1903  . . . O'Donnell . . . could turn a somersault on a floating log; of the birling matches, wherein two men on a single log try to throw each other into the river by treading squirrel fashion, in faster and faster rotation. . . .
1963  The object of birling is to see which of two opponents can remain balanced longest atop a log that is twirling and bouncing in the water.
1965  The process of getting the logs off the snags and sandbars and of marshalling them into rafts involved the now almost forgotten art of "birling," wherein the rivermen, pikes or peavies in hand, worked logs out of shallows by spinning them under their sure feet.