12.43 A cuckoo is calling nearby. A second cuckoo flies over the nest, lands nearby and starts calling- it is the call of a male cuckoo! The chicks react to this as a danger
Preening session- the chicks use their uropygial gland to get this greasy substance to rub over their feathers. It has many benefits- waterproofing and conditioning the feathers.
13.26 Karl flies away. Karl was in the nest for 11 minutes.
All the time while the parent is in the nest, the chicks are twittering. I'm not surprised why the parents don't want to stay in the nest for a long time