Female begging calls reflect nutritional need of nestlings in the hen harrier Circus cyaneus.

Our data provided support for the Offspring Need hypothesis. At nests where adlib food was provided females reduced their begging rate. These patterns suggested that female begging was an honest signal of need. However, begging continued even with adlib food and was only weakly associated with greater provisioning by males, suggesting that these calls may also play an additional role, possibly reflecting sexual or parent-offspring conflict.