Diurnal Variation in Mass, Metabolic Rate, and Respiratory Quotient in Anna's and Costa's Hummingbirds

@article{Powers1991DiurnalVI,
  title={Diurnal Variation in Mass, Metabolic Rate, and Respiratory Quotient in Anna's and Costa's Hummingbirds},
  author={Donald R. Powers},
  journal={Physiological Zoology},
  year={1991},
  volume={64},
  pages={850 - 870}
}
To examine how hummingbirds that do not enter torpor at night store and utilize energy, open-circuit respirometry and a strain gauge were used to measure daily variation in O2 consumption (V̇o2), CO2 production, respiratory quotient (RQ), and body mass in Anna's hummingbird, Calypte anna, and Costa's hummingbird, Calypte costae. During the day, V̇o2 was highly variable primarily because of differences in activity among individuals. At night V̇o2 varied little between individuals, but mean V̇o2… 
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