Millions of mammals navigate over thousands of kilometres each year. How they navigate during migration remains remarkably understudied compared to birds or sea turtles, however. A team of scientists led by the Leibniz-IZW in Berlin has now combined a mirror experiment simulating a different direction of the setting sun and a new test procedure to measure orientation behaviour in bats to understand the role of the sun’s position in the animal navigation. The results demonstrate for the first time that a migratory mammal species uses the sunset direction to calibrate their compass system. Furthermore the experiment, which is published in Current Biology, indicates that this capacity is not inherited, and first-time migrating young bats need to learn the importance of the solar disc at dusk for nightly orientation.