The number of young swans on the Thames has fallen in the last year, the annual census has found.
The 900-year-old survey comes to an end in Abingdon, Oxfordshire
The centuries-old Swan Upping tradition involves rowing skiffs from Sunbury to Abingdon, counting the number of swans on the river.
This year, it found many swans with only single cygnets, the Queen's swan marker, David Barber said.
He said it was due to a combination of natural predators and attacks such as vandalism and shootings.
Traditionally all swans in the UK belong to the reigning monarch.
Mr Barber told the BBC News website: "Numbers are slightly down on last year - a lot of the swan families have lost cygnets this year.
"In particular we found lots of swans with single cygnets around Reading.
"We've had no end of nests destroyed and shootings of birds - particularly in the Windsor area."
Nowadays, the Crown retains the right to ownership on some stretches of the River Thames and tributaries.
Ownership is shared with the Vinters' and Dyers' Companies which were both granted rights by the Crown in the 15th Century.