Effects of brood and group size on nestling provisioning and resource allocation in a communal bird.

This article investigates how variation in brood size and group size affects resource availability, distribution, and hatching asynchrony in the greater ani (Crotophaga major), a communally nesting cuckoo species in which multiple breeding pairs and helpers cooperatively raise a shared brood. Using long-term nest monitoring and video-recorded provisioning data, the study found that increases in the number of adult caregivers did not compensate for the greater number of nestlings in larger broods, resulting in decreased prey availability per nestling regardless of group size. Additionally, larger broods exhibited greater hatching asynchrony, which intensified competitive disparities and led to last-hatched nestlings receiving disproportionately less food. These findings suggest that the costs of increased offspring competition and asynchronous hatching may limit group size and influence parental care strategies in communal breeders.