In Pictures: Britain's annual swan census kicks off on River Thames

The annual Swan Upping Census in Britain started on Monday (July 15) on London's River Thames. Overseen by the Queen's Swan Marker, the census takes place over five days on the third week of July every year. It is the annual census of the swan population on stretches of the Thames and dates back to the 12th century when the English Crown first claimed ownership of all mute swans.