I love obscure collective nouns and swans are, apparently, fortunate enough to have 4 words to describe them when in groups, none of which I had known before looking them up. Of the 4, “lamentation” is definitely my favourite – it seems to evoke a feeling of classical sophistication that compliments the swans themselves rather well. The other two, “herd” and “bevy” don’t work as well for me. The final word, “wedge”, only applies when they are in flight so I couldn’t use it here to describe this group seen on the River Thames at Windsor last summer.
For the technically inclined...