Migratory birds are masters at navigating. Young animals that do not learn this in the first few months of their lives permanently lack a sense of direction - or so biologists previously thought. An Oldenburg research team has now discovered that nature gives the animals a second chance, for example after an injury.
In their first months of life, migratory birds learn to navigate. Among other things, they memorise the constellations. But what about young birds that can't see the sky at all, for example because they are being cared for in a closed room due to an injury? Have they missed the chance? Until now, science has assumed that they have. An Oldenburg research team led by doctoral candidates Bianca Alert and Andreas Michalik under the direction of biologist Prof Dr Henrik Mouritsen has now discovered in a study with robins that this is not always the case. Migratory birds can learn to navigate even later. The results have been published online in the renowned "Scientific Reports" of the "Nature" publishing group (NPG).
For more than a decade, Mouritsen, a biologist at the University of Oldenburg funded by the Volkswagen Foundation, has been researching how migratory birds manage to find their way. Little by little, his research group is uncovering the many secrets behind perfect navigation: among other things, the birds orientate themselves by the field lines of the Earth's magnetic field, which are perpendicular to the Earth's surface at the poles and almost parallel at the equator. They can perceive these and therefore know pretty much exactly what latitude they are at and where they are flying to. They also use the position of the sun to orientate themselves. When flying at night, the stars are an important navigational aid. Robins develop all these skills in their first months of life and use them to build up their almost perfect sense of direction for their flight in autumn.
But what happens when birds cannot see the stars? That was the initial question of the current study. It could be, for example, that they are injured and are being cared for by humans. This often happens in enclosed spaces.
Until now, experts assumed that birds can only learn the constellations in the first few months. The results of the Oldenburg researchers have now disproved this. They have shown in several experiments that even older birds can still learn to navigate if they have not seen stars in their first year of life. The animals simply build up their sense of direction a little later. The study thus proves that the navigational ability of migratory birds is much more flexible than previously thought. Birds that have been released into the wild therefore have a greater chance of survival, as they can also establish a functioning navigation system later on.