Every year, trillions of animals migrate for thousands of kilometres between their summer and winter habitats. Among them are several species of bats whose journeys in the dark of the night unfold largely unnoticed by humans and have only partially been investigated by science. A reconstruction of individual migration patterns of the common noctule (Nyctalus noctula) in Central Europe has now revealed that traveling distances vary greatly among individuals, yet overall, females cover longer distances than males.