28 May 2020

Cuckoo chicks have an innate GPS

Bird migration

By moving young cuckoos 1800 kilometres away from the nest in which they hatched, researchers from the University of Copenhagen have shown that the cuckoo chicks have an innate, internal GPS. The study lays the foundation for a broader understanding of bird migration.

Credit: Palle Sørensen

Cuckoos are nest parasites. This means that the adult cuckoo lays its eggs in other birds' nests. When the cuckoo chicks hatch, they are raised by the host bird and never see their own parents. Still, without anyone to teach it, a young cuckoo can find its way to a special wintering site in Africa – even if it is moved 1800 kilometres away from its original route.

‘It has always been a bit of a mystery how the cuckoo knows where to fly to during the first wintering. In our study, we have for the first time equipped the young cuckoos with tiny transmitters which we have followed via satellites. In this way, we have shown that this inner compass does not only lead the young cuckoos toward the south, but also back to the same route as used by the cuckoo chicks who have not been moved’, says Kasper Thorup.

‘We do not know how the young cuckoos’ inner GPS works, or what exactly they use to navigate. But it is remarkable that without any help from their parents, they instinctively know where to fly to without having been there before. If we can learn more about the movement patterns of cuckoos and other birds, we can gain a better understanding of bird migration in general – which is important both in terms of the spread of diseases and climate change’.

The cuckoo is just one of several hundred species flying south in the wintertime, guided by an internal instinct towards the right winter quarters. The inner compass is not something new. Previous studies have shown that if you put a migratory bird in a cage, it will start jumping toward the south as soon as autumn sets in. But this is the fir

Cuckoo with sender
By using a 5 gram sender the researchers can follow the cuckoo's movement via satellite. Credit: Kasper Thorup. 

st time it has been shown that very young cuckoos find their way back to a specific route, without any kind of guidance.

Space station satellite shall map the movement of animals

By equipping the cuckoo chicks with tiny transmitters, the researchers are able to follow their route via satellites. The transmitters weigh no more than 5 grams, but even if it does not sound like a lot, it equals 5% of the bird's own body weight. Therefore, the development of new technology is crucial in order to make such experiments possible.

‘The cuckoo is sufficiently big to carry the transmitters we have available today. But we are working to become even better at tracking the birds. In fact, we have a satellite on the International Space Station dedicated to locating birds and animals. We hope that we can start collecting more data on the movement patterns of animals, both mammals and birds and maybe even insects, as early as this autumn’, says Kasper Thorup.

Knowledge of migration directions and other movement patterns is important for several reasons. Knowing more about how animals move will make it easier to get an overview of the spread of diseases where animals are carriers. And as climate change threatens the habitats of the cuckoo and other animals, more knowledge about the internal GPS, movement patterns and wintering sites can help to ensure the survival of the animals.

The study ‘Flying on their own wings: young and adult cuckoos respond similarly to long-distance displacement during migration’ has been published in Scientific Reports.

Associate Professor Kasper Thorup
+45 35 32 10 51

Press Officer Amanda Nybroe Rohde
+45 23 64 94 25