"Clutch" performance

I opened the top of our bluebird house yesterday and was surprised to see that the eggs have hatched!! Mom and dad bluebird are nervously and ferociously guarding the nest against other birds. It seems that all kinds of birds must want to get a close up view of them, and they won't let any other birds near the nest.

Dad says that the term for a nest of baby bluebirds is a "clutch". I have no idea how that got started, but I guess my bluebirds have just delivered a "clutch performance"!!!!