During reproduction, birds are confronted with two requirements: building up their energetic reserves during the activity period, and provisioning the nest. Storing reserves imposes a higher flight cost and a lower hunting efficiency. This conflict is accentuated in species such as the Barn Owl (Tyto alba), where the nest food supply is entirely taken in charge by the male during a long period (ca. 37 days). We tested the prediction that Barn Owl males were postponing their meal to the end of the night in order to fly with a low body mass. Nocturnal changes in body mass (i.e., estimates of feeding events) were monitored remotely on six free-ranging Barn Owl pairs nesting in eastern France using an automated weighing system. Male Barn Owls were gaining the more weight at the end of the night, supporting the prediction that they make their biggest meal after the nest provisioning activities hunting period that is taking place at the beginning of the night.
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