Energy required for growth and development of white ibises was studied in captives by measuring daily metabolized energy through the nestling period. Captives used 5360 kcal, but their biomass growth differed from that of wild birds. By using the standard relation between existence metabolism and body weight, and assuming that energy requirements per gram biomass were age-dependent, it was estimated that the energy used by wild nestlings during growth was 8620 kcal. The applicability of laboratory data to wild populations should be verified by concurrent study of wild birds. Differences between growth of wild and captive birds show that biomass growth is slowed under unfavorable conditions, but also can accelerate to compensate for periods of slow growth.