She had mapped the geese for a decade: each autumn they crossed her grid in a clean diagonal from the northwest corner to the southeast, one cell per day. Like clockwork. Two days into this year's crossing she expected them at the center of the grid, the spot where she always set her blind. Instead the headwind had pushed the whole flock one cell east of the usual flyway. They were still heading southeast, still on schedule, but offset — every bird a column to the right of where it should have been. She missed the shot. The next day they corrected and resumed the old line as if the wind had never blown.