
1) Annual Thames bird expedition 
Found on 
https://www.crosswordclues.com/clue/swan-upping

 Swan Upping is an annual ceremonial and practical activity in Britain in which mute swans on the River Thames are rounded up, caught, marked, and then released. Traditionally, the British Monarch retains the right to ownership of all unmarked mute swans in open water, but only exercises ownership on certain stretches of the River Thames and its su...
Found on 
http://en.wikipedia.org/wiki/Swan_Upping

• (n.) A yearly expedition on the Thames to take up young swans and mark them, as by Companies of Dyers and Vintners; -- called also swan-hopping.
Found on 
http://thinkexist.com/dictionary/meaning/swan-upping/
Swan'-up`ping  noun  A yearly expedition on the Thames to take up young swans and mark them, as by Companies of Dyers and Vintners; -- called also 
 swan- hopping . [ Eng.] 
 Encyc. Brit. Found on 
http://www.encyclo.co.uk/webster/S/255

the taking up of young swans to mark them with nicks on the beak for identification. · an annual expedition for this purpose on the Thames.
Found on 
https://www.infoplease.com/dictionary/swan-upping
  No exact match found.