They came south in huge numbers because of a shortage of voles in their usual stomping grounds. They came south to eat our voles.
How has the great gray ruined my life? It started back in August (the occasion of the post Outside In), when a deer mouse ran across my bed as the cat and I sat on it watching television very early one morning. The deer mouse, unlike other native species of rodents (unlike voles), has a predilection for living in human-made structures. The mouse back in August was a sign of things to come. Now the house is full of mice--I hear them scurrying in the walls (I can hear one now), I hear them chewing up our stuff, last night I even heard them fighting. The cat caught one in a cupboard a week or so ago. I took it from her and evicted it (she wasn't quick to kill, and I didn't want her to lose it again in the house): it was back that night. I've cleaned out drawers, patched holes in the back of cupboards, put out poison (I'm sorry to say), and still I dread bedtime when the cat and I will once again be unable to sleep for the racket. (I think the cat might be enjoying the situation.)
So I blame the owl, for taking the voles, for creating the surge in the mouse population, driving intolerable numbers into the house. I blame the owl, but I could forgive if only the owl would return, and learn to love deer mice.