EMBRYOGENY OF OXYGEN-CONSUMPTION IN 13 ALTRICIAL AND PRECOCIAL BIRDS

The embryogeny of O-2 consumption (V-O2) was examined in 6 altricial a nd 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 continuou sly 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 1.7 7 kJ/g in precocial species. No marked differences concerning the occu rrence of a plateau phase could be found in the general course between the two developmental modes. This may reflect the existence of a basi cally identical course of the embryonic V-O2 in the examined bird spec ies.