Regulation of Oxygen Consumption and Body Temperature during Torpor in a Hummingbird, Eulampis jugularls

@article{Hainsworth1970RegulationOO,
  title={Regulation of Oxygen Consumption and Body Temperature during Torpor in a Hummingbird, Eulampis jugularls},
  author={F. Reed Hainsworth and Larry L. Wolf},
  journal={Science},
  year={1970},
  volume={168},
  pages={368 - 369}
}
The West Indian hummingbird, Eulampis jugularis, maintained its body temperature in torpor at 18� to 20�C over an ambient temperature range of 2.5� to 18�C. At ambient below 18�C oxygen consumption during torpor increased linearly with decreasing temperature. Thermal conductances were the same for resting and torpid Eulampis regulating their body temperatures at 40� and 18�C, respectively. 
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References

SHOWING 1-10 OF 12 REFERENCES
Oxygen consumption, thermal conductance, and torpor in the California pocket mouse Perognathus californicus.
  • V. Tucker
  • Biology
    Journal of cellular physiology
  • 1965
TLDR
Although P. californicus consistently enters into and arouses from torpor at ambient temperatures of 15° to 30°, the torpor cycle is severely disturbed at temperatures between 10° and 12°, and mice show irregular temporal patterns of torpor, do not enter torpor completely, and cannot arouse from torpora if body temperature falls below 15°.
Physiological responses of the giant hummingbird, Patagona gigas.
Physiological Studies on Hibernation in the Chipmunk
TLDR
A study of the seasonal activities of the eastern chipmunk to determine, first, whether or not it hibernates and, second, what, if any, physiological changes might parallel hibernation and perhaps serve as causative factors.
Heat regulation in some arctic and tropical mammals and birds.
A series of arctic and tropical mammals and birds at Point Barrow, Alaska (lat. 71° N.) and in Panama (lat. 9° N.) was subjected to various air temperatures in a respiration chamber where the heat
Thermal conductance in birds and mammals.
The oxygen consumption and temperature regulation of hibernating hamsters.
  • C. P. Lyman
  • Biology, Medicine
    The Journal of experimental zoology
  • 1948
Hibernation--hypothermia: an annual cycle of response to low temperature in the bat Myotis lucifugus.
  • M. Menaker
  • Environmental Science
    Journal of cellular and comparative physiology
  • 1962
Chief Veterinarian, generously granted permission to export these birds
    ...
    ...