Energy metabolism, respiration frequency and O2-consumption per breathing act in 11 different sunbird species during day and night

Abstract

The mean metabolic rates of 11 sunbird species are in the expected range based on data from other birds. Nevertheless the difference between day and night levels is greater (58–69%) than normal. Breathing frequencies among these birds correspond more closely to the (higher) levels found in empirical data for mammals. O2-consumption per breathing act remains nearly constant during day and night indicating that the diurnal cycle of O2-consumption is regulated mainly by modulation of breathing frequencies, which correlate directly with gaseous metabolism.