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

  title={Diurnal Variation in Mass, Metabolic Rate, and Respiratory Quotient in Anna's and Costa's Hummingbirds},
  author={Donald R. Powers},
  journal={Physiological Zoology},
  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… 
Diurnal rhythms of locomotor activity, changes in body mass and fat reserves, standard metabolic rate, and respiratory quotient in the free-living coal tit (Parus ater) in the autumn-winter period
The total energy budget of Parus ater in the autumn-winter period, energy balance, and the maintenance of constant flying weight along with the dynamics of fat reserves are discussed.
Respiratory Exchange and Ventilation during Nocturnal Torpor in Hummingbirds
It is concluded that a normal Q10 effect is sufficient to explain the metabolic rate of torpid hummingbirds and that transient CO₂ storage may occur during entrance into torpor but is not a prerequisite for entrance.
Diurnal rhythms of standard metabolic rate and respiratory quotient in the coal tit (Periparus Ater, Aves) during the autumn-winter period
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It is proposed that behavior and metabolic fuel choice are coadapted to maximize the rate of fat deposition during premigratory fattening.
Metabolic partitioning of sucrose and seasonal changes in fat turnover rate in ruby-throated hummingbirds (Archilochus colubris)
H hummingbirds alter fat turnover rates seasonally, with faster turnover during the summer, when they are lighter and have high daily energy expenditure, however, the preference for glucose as a substrate for fatty acid synthesis over fructose does not change seasonally.
Metabolic substrate use and the turnover of endogenous energy reserves in broad-tailed hummingbirds (Selasphorus platycercus)
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Field Metabolic Rate and Food Consumption by Free-Living Anna's Hummingbirds (Calypte anna)
We measured CO2 production and water flux using doubly labeled water in wild Anna's hummingbirds living in the Santa Ana Mountains of Southern California during autumn (September) of 1981. The
Oxygen Consumption of Torpid, Resting, Active, and Flying Hummingbirds
This investigation was supported, in part, by grant G-9238 from the National Science Foundation to Dr. W. R. Dawson, and by funds from the Graduate Student Research Fund, Horace H. Rackham School of Graduate Studies, University of Michigan.
Ambient Temperature and the Daily Energetics of Two Species of Hummingbirds, Calypte anna and Selasphorus rufus
These two hummingbird species employed different strategies for maintenance of positive energy balance in this study: C. anna behaviorally regulated energy stores, maximizing daily net energy gain by manipulating both energy gains and expenditures; S. rufus relied more on physiological means (i.e., torpor) to conserve energy overnight.
Oxygen consumption during hover-feeding in free-ranging Anna hummingbirds.
Rates of oxygen consumption during hover-feeding of wild, unrestrained, adult male Anna hummingbirds were measured with an artificial outdoor feeder converted into a respirometer mask, automatically detecting the presence of a hummingbird from a drop in the O2 concentration and photoelectrically timing the duration over which the feeder functioned as a mask.
Energy Metabolism: Errors in Gas-Exchange Conversion Factors
When an animal fasts throughout the period of measurement of CO2 production but is presumed to be eating, the error of estimating energy metabolism can be as high as 23% for herbivores; the error increases steadily with the protein content of the diet for ureotelic carnivores.
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Field metabolic rates (FMRs or HF), all measured using doubly labeled water, of 23 species of eutherian mammals, 13 species of marsupial mammals, and 25 species of birds were summarized and analyzed
The Function of Torpor in Hummingbirds
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