barn swallows at play

This was pretty fascinating: Barn swallows, skimming the surface of the river (today like glass). One has a large leaf or a flat piece of bark in its beak. It flies straight up about 30 feet, drops it, and zigs in and out as the object falls (in a leafish sort of way) towards the river, managing to catch it again before it hits the surface of the water. Two other birds swoop in and they take turns picking it up, dropping it, and all trying to catch it without having a collision or letting it hit the water. The few times that it wasn't caught, they took turns skimming the glassy surface to pick it up again. This all went on for several minutes, and several rotations, without a sound, until the toy eventually submerged and they weren't able to pick it out of the water again, at which point they all went off to do other things for a bit.

It looked like kids playing kick the can.