Embryogeny of oxygen consumption in 13 altricial and precocial birds

The embryogeny of O2 consumption (VO2) was examined in 6 altricial and 7 precocial bird species (egg mass: 1.13 to 330 g). The 13 species studied were measured in most cases daily, some of them were continuously measured for 24 hours. 10 of 13 species exhibited a clear plateau-phase in about the last fourth of their embryogeny. Mean total energy production during incubation period was 1.83 kJ/g in altricial and 1.77 kJ/g in precocial species. No marked differences concerning the occurrence of a plateau phase could be found in the general course between the two developmental modes. This may reflect the existence of a basically identical course of the embryonic VO2 in the examined bird species.