Peacocks

This is sad, but in preparation for the pub quizzes I'm trying to remember the collective name for various groups of birds.

For example its a Murder of Crows; a Cast of Falcons; a Charm of Finches, a Parliament of Owls; a Siege of Herons, etc.

So what about Peacocks? - well here it gets a bit complicated - it seems to be a Muster but can also be an Ostentation; sometimes it can be a Party, and to complicate it further a group of Peahens is a Harem.

Who thinks these things up?!