King Charles III's annual Swan Upping census began on the River Thames. This five-day tradition, dating back to the 12th century, involves assessing the health of the monarch's swans. Teams of oarsmen, a vet, and the King's Swan Marker record swan numbers and check for disease or injury. Swan populations have declined recently due to avian flu, but the first day of this year's census showed a positive start with 16 young swans recorded. The census continues until Friday, traveling upstream.

Prepared by Emily Rhodes and reviewed by editorial team.