This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Young Bewick's swans only survive their first spring migration if they stay with their parents long enough. If they lose their parents in winter, they leave later and are unable to keep up with the rest of the population.
As a result, there is a greater chance that they will die in their first year of life. This is shown in new research by biologists from the UvA and NIOO-KNAW, together with American and German colleagues, published Aug. 20, 2026, in the journal Behavioral Ecology and Sociobiology. Using GPS transmitters and DNA analysis, Hans Linssen and his colleagues analyzed 55 swans—both adults and juveniles—from 12 entire swan families.
This gave the researchers insight into family ties, how long families stayed together and what happened when the bond was broken. Bewick's swans breed on the Arctic tundra of European Russia, and in the fall, they fly in family groups to the Netherlands and surrounding countries to spend the winter. Normally, the families stay together until at least halfway through the young's first spring migration back to the north, when the young are nearly 1 year old.
For 10 of the 24 young in the study, things turned out differently: They lost their parents during the winter following disturbances at roosting and feeding sites, primarily because hunters invaded a protected nature reserve important to the swans. On average, these orphaned swans departed for the spring migration nearly a month later than other juvenile swans and were much less likely to survive the following winter. The survival rate among the orphans was 40%, compared with 86% among young that stayed with their parents for most of the migration.
"This poignantly shows that living and learning in a family group is not only useful for the young swans, but literally of vital importance," says Linssen. One orphaned swan did not leave northern Germany until April, following the same route as its peers but flying a considerable distance behind them. The last GPS signal was picked up over Latvia; after that, the swan disappeared from all records.
For several young orphans, the transmitter signal was never picked up again, indicating that they did not survive the summer. Linssen said: "There is no telephone network in the swans' breeding area. As a result, the GPS transmitters cannot send their locations for months.
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