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.
A fairly common pub name, "The Swan with two necks," actually means two nicks on the beak to show whether or not it's a Royal Swan!
Mute swans are the only truly British swans. The others come in from Russia or Iceland in the winter. Bewicks and Whoopers and they have yellow on their beaks