If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offsprings' calls.

如果雏鸟双亲是根据雏鸟乞食的叫声响亮程度来把食物分给叫声响亮的健康雏鸟的话，那么鸟类双亲就是根据雏鸟乞食声音来决定如何分配食物的。