Many years ago as a student I had occasion to travel in Europe during the summer.
Without much money, I rented a room from a family in a poor part of town. It was terribly hot. With no air conditioning or fan, I opened the window and hoped I would fall asleep.
Maybe 1:00 a.m., dozing in the still and humid night, I became aware of a noise out my window and would discover that it was coming from an adjoining alley behind the house. A scratching noise; long silence – perhaps a full two or three minutes; scratching again.