Female Helpers Lighten Mothers’ Workloads and Increase Egg Size in Desert Birds

White-browed sparrow weavers live in family groups in which only a dominant pair breeds and their grown-up offspring, particularly females, help to feed nestlings. The study, by researchers at the University of Exeter, found that mothers increased the size of their eggs when they had more female helpers on hand. The number of male helpers did not affect egg size, probably because male helpers feed chicks at substantially lower rates than female helpers.