Droppings are the solid waste that animals and birds leave behind — what they drop as they go. English uses this when a cleaner, farm, or garden word is wanted, rather than “poo.” You hear it most about birds (on a car, a statue, a windowsill), and also about mice, rabbits, sheep. It is almost always plural: we say droppings, not “a dropping,” except sometimes for one small pile. A vet or a farmer uses it without thinking twice. We do not usually use it for people.