There are chickens in there somewhere. They're not coming out to play. It's rained every day since they hatched - their experience of this world is a wet one - they can't be blamed for thinking this a damp and miserable place. Better stay in. In might be preferable to Out. I was going to describe them as 'mardy' - meaning 'childish, easily upset or cowardly', but on looking it up in my favourite Urban dictionary I see the usage favours 'Grumpy. Surly. Like a moaning child who doesn't get his way.'
Nope, I don't think they are that stroppy. They're Big Girls' Blouses, Wimps, Wet Nellys. (The latter's a Scouse bread pudding but what a wonderful derogatory term it makes: 'Ger'on with it yer great wet nelly'.)
Bless 'em, they are only about 10 days old and still fit under mum's wings