R. Prinzinger et V. Dietz, QUALITATIVE COURSE OF EMBRYONIC O-2 CONSUMPTION IN ALTRICIAL AND PRECOCIAL BIRDS, Respiration physiology, 100(3), 1995, pp. 289-294
The course of embryonic V-O2 was examined in 24 altricial and 27 preco
cial bird species to test differences in its phenology. Some authors s
uggest that altricial species lack a plateau in V-O2-development found
in precocial species. Based on the recently available data we find th
e following: All species (except members of the family Megapodiidae) e
xhibit a plateau. Their V-O2-development follows an identical basic co
urse which can be described by an exponential increase interrupted by
the plateau. There seems to be no fundamental difference between altri
cials and precocials with respect to the general presence of a plateau
. In small altricials the plateau lasts only a few hours. It can be ov
erlooked easily when the measurement is not continuous or when many in
dividual measurements are averaged. However, the plateau-V-O2 is lower
(about 35%) and shorter (12.4% of incubation time; 16.9% in precocial
s) in the altricials. Total energy consumption during incubation is 1.
9 kJ/g in altricial and 2.2 kJ/g in precocial species.