day 4

The unhatched egg has been disappeared by the parent bird(s).
Both parents have been conscientiously feeding the remaining two chicks, so they're to and from the nest quite frequently.
I am allowed to sit on my nice verandah, but it's perfectly clear when they want me to leave - there's a certain amount of lurking about in the trees nearby and I'm starting to recognise the "I've got a terrific grub for the kids - when do you think she'll piss off so I can feed them?" calls they make to each other.

I'd say they're almost twice the size they were when they first hatched. Not much down on them yet though.