Migratory bats use a magnetic sense to navigate long distances,  calibrating their internal compass based on the position of the setting sun each evening.

Many animals may use Earth’s magnetic field either to orient themselves or to navigate, including turtles, birds and possibly even humans. Until now, there has been no direct evidence that migratory mammals also use this sense, called magnetoreception.

Migratory bats travel hundreds or even thousands of kilometres each year. As nocturnal voyagers, they can’t rely on visual cues, such as …