Corticosterone triggers high-pitched nestlings' begging calls and affects parental behavior in the wild zebra finch

Nestlings beg to parents to communicate their need. Nevertheless, the specific signal driving parental care remains only partially understood. No study to date has been able to link a specific change in the physiological state of the young with, on the one hand, the modulation of a precise component of its begging behavior and, on the other hand, a direct modification of parental behavior reflecting an adjustment to an appropriate level of care. Here we orally administrated either exogenous corticosterone or a peanut oil control to free-living zebra finch nestlings and recorded begging behavior directly after treatment. Using a continuous automated monitoring system to record parental behavior in the wild, we simultaneously monitored the rate and duration of parental nest visits and foraging behavior at artificial feeders during 6 days posttreatment. We show that corticosterone modified the begging calls' spectrum. Parents of corticosterone-treated broods spent more time in the nest and in feeders, and their older nestlings gained more body mass. Begging calls thus show a corticosterone-driven flexibility, which may inform parents of nestlings' physiological state and allow them to provide an appropriate level of care.