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

摘要: To examine how hummingbirds that do not enter torpor at night store and utilize energy, open-circuit respirometry a strain gauge were used to measure daily variation in O₂ consumption ($\dot{V}o_{2}$), CO₂ production, respiratory quotient (RQ), body mass Anna's hummingbird, Calypte anna, Costa's costae. During the day, $\dot{V}o_{2}$ was highly variable primarily because of differences activity among individuals. At varied little between individuals, but mean more than two times predicted from for resting postabsorptive birds. For C. 24-hr energy expenditure similar free-living Diel fluctuations large, up 16% both species. However, much observed change probably due factors other changes fat content. The RQ well above 1.0 throughout suggesting continuous deposition fat, RQs remained high (> 0.85), indic...