There must be some point when herons know they can't make the trip south.
I started wondering this sometime in October as I walked the woods along the river and saw the regulars--geese, mallards, gulls, sans the tall delicate birds that approach the river with semblances of curiosity and grace. During the summer I would see the white ones perched in the large oaks along the river's embankment; from the road they looked like draped handkerchiefs, pure white, newly laundered.
Today I found my answer in Mary Oliver's poem "Herons in Winter in the Frozen Marsh." It's funny how poems can answer questions churning in my mind; it's almost as if I'm being directed. This is what the old herons do: they wait. They wait as the cold whittles their bones and starvation loosens their flesh. At some point their "wings crank open/ revealing the old blue light" and they let go, "first one then the other ... into the ditches and upheavals." They become the water, the marsh, the bending grass.