Birds are frequently mentioned in Gilbert and Sullivan operettas, but in the number, “Sing Me Your Song” from “Yeomen of the Guard,” the lyrics "It is sung to moon by a lovelorn loon," I am not sure the reference was avian.
Common Loons do live in England, just as Gilbert and Sullivan did, but the Brits call them "Great Northern Divers."
In British slang, a “loon” was a crazy person, or a lunatic.
And that may explain the phrase "crazy as a loon," but others believe that the nighttime call of a Common Loon is rather maniacal.
However, when we hear loons this time of year, they are probably lovelorn.
Mated pairs have stopped their evening serenades to the moon, putting their efforts into aggressively protecting their territories and their chicks.
But there are also groups of loons that gather in late summer and early fall. Theses are the non-breeders. Perhaps they couldn't find a territory or attract a mate. Maybe they lost their mates. They are the lovelorn loons. Or not.
Some researchers think they are swinging singles, hanging out and partying because they do not have territories or offspring to defend.
Still, congregations of unmated loons are still carrying on, dancing on the water and singing to the moon.
Oh, and you know collective name for loons? An Asylum.