Jun 30, 2009, 11:02 GMT
Britain's Queen Elizabeth has ordered staff to count her swans.
The 83-year-old monarch has decreed that the annual Swan Upping ceremony will be conducted by the official Swan Marker David Barber between July 20 and 24.
The tradition, which dates back to the 12th century, sees Barber and a bird expert rowing up the River Thames in a traditional skiff wearing special scarlet uniforms.
During the exhausting five-day expedition, the two men with count, weigh and measure all the swans and cygnets they see.
A statement released by Buckingham Palace said: "With the assistance of the Queen's Swan Warden, Professor Christopher Perrins of the University of Oxford, the swans and young cygnets are also assessed for any signs of injury or disease."
Custom dictates the queen owns all unmarked, mute swans in open water, but Elizabeth only claims those that live on the Thames and its tributaries.
In medieval times, the Swan Marker would try to catch as many swans as possible as they were a much sought-after delicacy at royal feasts and banquets.
This year, the researched will focus on examining the extent to which the birds are affected by fishing tackle and aggressive dogs.
For the first time, Elizabeth will join them on one leg of their journey, following them up the river before visiting a local school group studying swans and cygnets.
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