Volunteer birders across the UK and Ireland will take part in the six-yearly international swan census this weekend, counting whooper and Bewick’s swans. The survey, which last took place in January 2020, aims to track population changes of these wintering wildfowl.
The whooper swans have mainly travelled from Iceland, while Bewick’s swans come from Siberia. The census covers a wider area than most bird counts, surveying overwintering populations in the eastern Mediterranean, central Asia, Iceland, continental north-west Europe and around the Black Sea.
In recent years, the species’ fortunes have diverged widely. The UK’s winter population of whoopers has almost doubled in the past quarter century to 20,000 birds. In contrast, Bewick’s numbers have plummeted, with only 700 birds reported in early 2025, almost all at a few well-known sites in southern England.
Climate breakdown may be the cause of the whooper swan’s rise and the Bewick’s swan’s fall. Mild winters have improved the whooper’s survival rate, increasing the Icelandic breeding population. Meanwhile, mild winters in Scandinavia and the Low Countries mean many Bewick’s swans are no longer crossing the North Sea to the UK and Ireland.
