In late summer, some bat species migrate from northern Europe along the coastlines to their wintering sites in central and western Europe. Until now it was assumed that all bats travelled in the same direction during the migration. However, the reality is more complex: On the Latvian Baltic coast, a research team led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) reconstructed the flight paths of Nathusius’ pipistrelle bats using ultrasound microphones. Most animals flew southwards in late summer, but on some days 20 percent travelled in the opposite direction – presumably owing to weather conditions.