Thank you all for your clues, a excellent selection with lots of kinds of hatches. With 4 votes, rossim is our clear winner with the very neat and apposite:
Just like that, chickens emerge (5)
Well done. Is that the first time you've won?
Mattrom also got 4 votes but over 3 clues. Is this a record?
I haven't awarded a twee film of chicks hatching, but I like this, especially for the background music-
www.youtube.com/watch?v=FDKgLfWheoI
It is anything but twee.
The real prize is something different-
www.youtube.com/watch?v=VsKTG30g3mw
RIP, AB