Tramps and vagabonds have marks they make on gateposts and trees and doors, letting others of their kind know a little about the people who live at the houses and farms they pass on their travels. I think cats must leave similar signs; how else to explain the cats who turn up at our door through the year, hungry and flea-ridden and abandoned?
Neil Gaiman, M Is for Magic
cats, stray-cats, the-price