Swan Census to Track Decline of Irish Winter Flock Amid Rise of British Counterpart
Volunteers will this weekend take part in the sixth international swan census, a six-yearly survey that tracks the fortunes of the UK and Ireland's wintering bird populations. The event aims to monitor changes in the numbers of two species: whooper swans from Iceland and Bewick's swans from Siberia.
The census typically takes place in January but has now shifted to coincide with the birds' migration patterns, which sees them moving south for the winter. This year's survey will cover areas where both species are known to congregate, including the eastern Mediterranean, central Asia, and parts of continental north-west Europe, as well as Iceland.
In recent years, the swans have experienced a significant divergence in their populations. The UK has seen an almost doubling of its whooper swan numbers over the past quarter century, with estimates suggesting that around 20,000 birds now spend the winter there. Conversely, Bewick's swans, which were once abundant in England, are now largely absent from most sites except a few isolated areas in southern England.
Climate change is thought to be a major factor behind these diverging fortunes. Mild winters have led to improved survival rates for whooper swans, boosting the breeding population in Iceland. Meanwhile, equally mild conditions in Scandinavia and the Low Countries have made it unnecessary for many Bewick's swans to migrate across the North Sea to reach the UK and Ireland.
Volunteers will this weekend take part in the sixth international swan census, a six-yearly survey that tracks the fortunes of the UK and Ireland's wintering bird populations. The event aims to monitor changes in the numbers of two species: whooper swans from Iceland and Bewick's swans from Siberia.
The census typically takes place in January but has now shifted to coincide with the birds' migration patterns, which sees them moving south for the winter. This year's survey will cover areas where both species are known to congregate, including the eastern Mediterranean, central Asia, and parts of continental north-west Europe, as well as Iceland.
In recent years, the swans have experienced a significant divergence in their populations. The UK has seen an almost doubling of its whooper swan numbers over the past quarter century, with estimates suggesting that around 20,000 birds now spend the winter there. Conversely, Bewick's swans, which were once abundant in England, are now largely absent from most sites except a few isolated areas in southern England.
Climate change is thought to be a major factor behind these diverging fortunes. Mild winters have led to improved survival rates for whooper swans, boosting the breeding population in Iceland. Meanwhile, equally mild conditions in Scandinavia and the Low Countries have made it unnecessary for many Bewick's swans to migrate across the North Sea to reach the UK and Ireland.