Resting metabolic rate and erythrocyte morphology in early development of thermoregulation in the precocial grey partridge (Perdix perdix).

In the early stages of development of thermoregulation in grey partridge, a typical precocial species, I measured the resting metabolic rate (RMR) and body temperature (Tb) in the thermoneutral zone (TNZ) and the parallel changes in the size of erythrocytes and their cell nuclei. The strong positive correlation between the mass-independent (residuals versus body mass) values of Tb and RMR indicates a close relationship, between these physiological parameters in the first week of life of partridges. In the ontogeny of this species, the dimensions of erythrocytes correlated inversely with the mass-specific metabolic rate (expressed in mW g(-1)), claiming its status as an important and metabolically useful measure of development. The correlation coefficient of these two variables, at the level of individual development within a species, has been further enhanced in the inter-specific analysis at the level of the order Galliformes. The characteristics of changes in the erythrocyte size, in parallel with the dynamics of the resting level of heat production development, in the important period when the thermoregulation is assuming its form in precocial birds, supply new data pertaining to this strategy of avian development.