Rise in swan numbers despite bird flu outbreak

Swan Uppers on the River Thames are hoping to see another rise in cygnet numbers this year, despite a fresh outbreak of bird flu over the winter.

The annual five-day census of the Thames's mute swan population begins on Monday, travelling 79 miles from Sunbury Lock Cut in Middlesex to Abingdon Bridge in Oxfordshire.

Just 86 cygnets were counted in 2024, rising to 115 in 2025, and organisers say they are hopeful of a similar increase this year.

The King's Swan Marker, David Barber, said the rise in 2025 had been "very positive" and that he was hopeful of similar progress in 2026 "in spite of another outbreak of bird flu that affected the waterfowl population over the winter."

He said cygnets faced a difficult start in life, with risks from predators like birds of prey, foxes and dogs, as well as disease and pollution.

Members of the public who monitor the location of swans local to them are "a great help to the swan population", he added.

Swan Upping dates back to the 12th century and takes place every year during the third week of July.

Six traditional rowing skiffs will travel the Thames over five days, with the Swan Marker's team counting, weighing and examining swans and cygnets for injury or disease.

All cygnets are fitted with a British Trust for Ornithology ring, allowing their movements to be traced in future.

Primary schools along the route are again expected to visit this year, giving pupils the chance to see cygnets up close and learn about swan ecology.

This year's Swan Upping runs from Monday until Friday, passing through Windsor, Marlow, Henley, Reading and Wallingford before finishing in Abingdon.