Genes Determine Willow Warbler’s Migration Routes

Since antiquity, humans have been fascinated by birds’ intercontinental migratory journeys. A new study from Lund University in Sweden shows that two areas (loci) in their genome determine whether a willow warbler flies across the Iberian Peninsula to western Africa, or across the Balkans to eastern and southern Africa. Researchers have long known that the behavior that causes songbirds to migrate in a specific direction towards a remote winter location is something they are born with. The recent study aims to further understanding of the genetics behind this behavior. With the help of modern technology, and 20 years of research into the genetics of songbirds and their migration routes, the researchers managed to identify which parts of the genome determine the songbirds’ routes. “The songbirds’ direction of travel is determined by two areas in the genome. Genes from the southern subspecies take the bird towards the southwest, across the Iberian peninsula to their wintering grounds in western Africa. Genes belonging to the northern subspecies instead lead the willow warblers towards the southeast, over the Balkans, to locations in eastern and southern Africa,” says Staffan Bensch, PhD, biology researcher at Lund University. The new research was published on January 11, 2023 in Nature Communications. The open-access article is titled “Migration Direction in a Songbird Explained by Two Loci.”