Breaking up of swan families in winter disrupts spring migration

Breaking up of swan families in winter disrupts spring migration, according to new research published Aug. 20, 2026, in the journal Behavioral Ecology and Sociobiology. Scientists from the University of Amsterdam (UvA), the Netherlands Institute of Ecology (NIOO-KNAW), and collaborators in the United States and Germany found that young Bewick’s swans who lose their parents during the winter face significant challenges during their first spring migration. These swans depart later than their counterparts and have a drastically lower survival rate, according to the study. The research focused on 55 Bewick’s swans, adults and juveniles, from 12 complete families. By using GPS transmitters and DNA analysis, scientists tracked the movements and family dynamics of the swans. The study revealed that young swans typically remain with their parents until at least halfway through their first spring migration, which begins in early March and lasts several months. During this time, the young learn essential survival skills from their parents. However, for 10 of the 24 young swans studied, the family unit was disrupted. These swans lost their parents during the winter due to disturbances at key roosting and feeding areas. The primary cause of these disruptions was the intrusion of hunters into a protected nature reserve critical to the swans’ winter habitat. Without parental guidance, these young swans faced significant difficulties in timing their migration correctly. GPS data showed that the orphaned swans began their spring migration approximately one month later than their non-orphaned peers. This delay placed them at a disadvantage, as they could not keep pace with the larger swan population moving northward. The survival rate among the orphaned swans was just 40 percent, compared to 86 percent for those who remained with their parents throughout the migration. One of the orphaned swans, identified as 036T, had a different experience. Its mother was killed by hunters at the wintering site. In February, 036T traveled to Great Britain and joined another family. It spent two weeks with this new group before continuing its journey. However, the fate of many other orphaned swans remains unknown. One swan did not leave northern Germany until April, following the same route as others but significantly behind. Its last GPS signal was detected over Latvia, after which it vanished from tracking records. For several other young orphans, the GPS transmitters stopped transmitting altogether, suggesting they did not survive the summer. Scientists noted that the lack of communication infrastructure in the swans’ breeding area means GPS transmitters cannot relay real-time location data for extended periods. Researchers can only monitor the swans once they return to southern regions in October, when satellite coverage resumes. This gap in monitoring makes it difficult to determine the exact fates of many of the orphaned swans. The findings highlight the crucial role of family units in the survival of young Bewick’s swans. According to Hans Linssen, one of the lead researchers, the results show that staying with parents is not merely beneficial but essential for the young swans’ survival. “Living and learning in a family group is not only useful for the young swans, but literally of vital importance,” he stated. The study underscores the impact of human activities on wildlife, particularly in protected areas. The incursions by hunters into the swans’ wintering grounds have led to the disruption of family structures, which in turn affects the survival rates of the young. Conservationists and wildlife experts are calling for stricter enforcement of protections in these habitats to prevent further disturbances. As the research continues, scientists plan to analyze additional data from future migrations to better understand the long-term effects of losing parental figures. They hope to identify strategies to mitigate the risks faced by orphaned swans and improve conservation efforts for Bewick’s swans in the region.