In this video You can watch, how storks killing their babies. These are sad moments, but it is a part of nature. Stork kills its own baby, when necessary, when not enough food or storklet is sick. In this case the adult stork throws baby out of nest.
the reason the little one was removed was because it is the last hatch, and was not as big and strong as the others.
Nature dictates that the weak should not survive, Instead of using so much food, energy and more time on the little one, it os better spent toward those that are stronger.
They have limited amount of time in the year that they can afford to care for their brood, Eliminating the weaker and smaller one or ones shortens that time that they have to care for their young.
The others will grow faster now because the food shared between them is now a 4-way split instead of a 5-way split.
Not to mention, being smaller means you get overlooked sometimes when feeding does occur, Instead of prolonging the small chick’s suffering, removal was the best option.