These chicks were asynchronously hatched, one on the 13th of June and the other on the 15th of June.
Throughout the nestling stage, the younger chick was observed to be more intense in its begging behaviour. Upon the approach of a parent bird, the younger chick was always observed to display a longer begging duration, a higher begging stretch and louder, more persistent begging calls:
That seemed to be enough to compensate for the disadvantage of having arrived late. Blessed with such great post-hatching vigour, it was able to receive sufficient food from their parents to speed up its growth and to soon catch up in size with its older sibling. Both fledged when they were 10 days old. The younger one (below left) is now 12 days old. Miraculously, all it took was barely 2 weeks for it to shake off the huge disadvantage it was born into.