When dad comes home to find a new kestrel chick in the nest

The difference between when the adult female returned to find a new kestrel in the nest to when the male returns is stark. Look how calm the new kestrel chick this time. Instead of snatching the food from the adult male, it quietly accepts morsels. Is this a result of the calming influence of this elder, statesman dad? Or perhaps the new kestrel is a little more relaxed - and a little less hungry!
If you aren't already following the story, this kestrel was found abandoned and I have introduced it to the nest in the hope that these wild birds will raise it.