Bird migration has long fascinated scientists, who continue to question how birds learn to find their way to distant locations. While it has been well established that birds migrate in groups, there is limited information on how individuals that migrate together interact. To investigate, a team of researchers from Finland, Sweden and the UK tracked bird families with GPS devices.
“We wanted to get a better idea of how the migratory skills of birds are passed from one generation to another in a species where individuals normally migrate together,” said study lead author Patrik Byholm of the University of Helsinki.
Caspian terns were selected for the study. They are a fish eating waterbird that normally migrates in small groups. GPS tracking of the birds showed that the male parents are responsible for leading their young during their first migration from the Baltic Sea to Africa.
This is known as “guiding behavior” which the study identified as the responsibility of the biological father, and in one case a foster father took on this role. The researchers were unable to determine why males, instead of females, were leading their young.
“This is very fascinating behavior, which we really did not expect to find when setting up our study,” said Byholm.
The experts also found that during migration, young individuals kept close to an adult bird. In cases where young birds lost contact with their parent, they did not survive. Staying close to an experienced adult is critical for young birds to survive their first migration.
The study revealed that during the first solo return trip, the young terns used the same migratory route their father guided them on.
“This indicates that in Caspian terns, migration knowledge is inherited through culture from one generation to another. This has consequences on the decisions individuals make years after they first migrated with their father,” said study co-author Susanne Åkesson from Lund University. Learning the right migratory routes is critical to survival.
Understanding how Capsian terns and other birds learn how to migrate is important to predicting how these birds will fare in a changing climate. This study highlights how the future survival of Caspian terns relies on passing migration knowledge down from one generation to the next.
The research is published in the journal Nature Communications.