On the Variability in Energy Allocation of Nestling Birds

An energy budget is presented for free-living nestling Double-crested Cormorants (Phalacrocorax auritus), an altricial species, and is compared to those from four other studies performed under natural conditions, for another altricial species, two semi-precocial, and a precocial species.Total energy intake, standardized for body size, appears variable, and there are several important differences among the budgets, including differences between budgets for the same developmental mode.Although limited in extent, these data and other evidence support the hypothesis that nestling energy budgets are molded by natural selection, correlate to adult reproductive strategy, and can reflect adaptation to selective pressures on a species.