The key to winter survival: daily torpor in a small arid-zone marsupial

@article{Krtner2008TheKT,
  title={The key to winter survival: daily torpor in a small arid-zone marsupial},
  author={Gerhard K{\"o}rtner and Fritz Geiser},
  journal={Naturwissenschaften},
  year={2008},
  volume={96},
  pages={525-530}
}
Mammalian hibernation, which lasts on average for about 6 months, can reduce energy expenditure by >90% in comparison to active individuals. In contrast, the widely held view is that daily torpor reduces energy expenditure usually by about 30%, is employed for a few hours every few days, and often occurs only under acute energetic stress. This interpretation is largely based on laboratory studies, whereas knowledge on daily torpor in the field is scant. We used temperature telemetry to quantify… 
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References

SHOWING 1-10 OF 39 REFERENCES
The role of torpor in the life of Australian arid zone mammals.
TLDR
It appears that the success of small insectivorous/nectarivorous mammals and perhaps rodents in the Australian arid zone is partially due to their use of torpor, which appears to prolong life span.
Torpor and basking in a small arid zone marsupial
TLDR
The findings suggest that although overlooked in the past, basking may be widely distributed amongst heterothermic mammals and the energetic benefits from torpor use in wild animals may currently be underestimated.
Thermal Biology, Torpor, and Activity in Free‐Living Mulgaras in Arid Zone Australia during the Winter Reproductive Season
TLDR
In a resource‐poor environment during the least productive part of the year, frequent torpor seems to provide the means to compensate for the increased energetic costs associated with reproduction.
Torpor and activity patterns in free-ranging sugar gliders Petaurus breviceps (Marsupialia)
TLDR
It is shown that cold or wet conditions curtail foraging in wild sugar gliders and that they employ daily torpor regularly during adverse weather, which suggests that minimisation of energy loss by the use of torpor in sugar glider is pivotal for their survival in the wild.
Seasonal Study of Spontaneous Daily Torpor in the White-Footed Mouse, Peromyscus leucopus
TLDR
Daily torpor was observed in both mouse populations from mid-December through mid-February, and 96% of the animals in torpor were found in groups of two to six mice, and all mice in the nest box were usually torpid.
Yearlong hibernation in a marsupial mammal
  • F. Geiser
  • Environmental Science
    Naturwissenschaften
  • 2007
TLDR
These observations represent the first report on body-fat-fuelled hibernation of up to an entire year and provide new evidence that prolonged hibernation is not restricted to placental mammals living in the cold.
The Impact of Daily Torpor on Energy Requirements in the Djungarian Hamster, Phodopus sungorus
TLDR
Calculations show that daily torpor in Djungarian hamsters may serve to allow the continuation of foraging at low Ta's during winter in the Siberian steppe and save substantial amounts of energy by lowering average metabolic rates during the normothermic phase of the day.
Summer dormancy in edible dormice (Glis glis) without energetic constraints
TLDR
Almost year-round torpor has evolved as a strategy to escape birds of prey, the major predators of this arboreal mammal, and clearly helps in explaining the unusually high longevity of dormice.
Seasonality of torpor and thermoregulation in three dasyurid marsupials
TLDR
The results suggest that seasonal changes in the pattern of thermoregulation and torpor in small dasyurids may be more distinct than in larger species.
Hibernation versus Daily Torpor in Mammals and Birds: Physiological Variables and Classification of Torpor Patterns
TLDR
Comparisons of several physiological variables appear to justify a distinction between the two torpor patterns, but of all variables tested, only the frequency distributions of maximum torpor bout duration and the minimum V̇o2 showed a clear gap between daily heterotherms and hibernators.
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