I was inside, sitting next to an open window, when I heard a tapping I couldn't identify.
It seemed to be coming from out on the patio or near the garage.
But when I went outside to investigate, I saw nothing. At first, anyway.
Then it resumed, and I happened to look up. A utility worker was high up on a pole rising from a spot near where four backyards meet.
I told him I had been baffled by the sound.
"Darned squirrels," he said, guessing at what might have been one of my theories.