Daily torpor and hibernation in birds and mammals

@article{Ruf2015DailyTA,
  title={Daily torpor and hibernation in birds and mammals},
  author={Thomas Ruf and Fritz Geiser},
  journal={Biological Reviews},
  year={2015},
  volume={90}
}
Many birds and mammals drastically reduce their energy expenditure during times of cold exposure, food shortage, or drought, by temporarily abandoning euthermia, i.e. the maintenance of high body temperatures. [] Key Method We use Gaussian-mixture cluster analysis as well as phylogenetically informed regressions to quantitatively assess the distinction between hibernation and daily torpor and to evaluate the impact of body mass and geographical distribution of species on torpor traits. Cluster analysis…
Seasonal Expression of Avian and Mammalian Daily Torpor and Hibernation: Not a Simple Summer-Winter Affair†
  • F. Geiser
  • Environmental Science
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  • 2020
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  • F. Geiser
  • Environmental Science
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  • 2019
TLDR
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It is demonstrated that food store availability affects torpor expression and also highlights variation in torpor patterns and energy-saving strategies in common hamsters.
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TLDR
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TLDR
Recent advances in the understanding of energy balance and its neuronal and endocrine control during the most extreme metabolic fluctuations in nature: daily torpor and hibernation are focused on.
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TLDR
It appears that a complete suite of adaptations to metabolism, vital physiological functions, and thermogenic mechanisms is required for the successful expression of the hibernation phenotype.
Avian torpor or alternative thermoregulatory strategies for overwintering?
TLDR
Low BMR, communal roosting and insulation of the roost nest enable white-browed babblers to survive winter without resorting to torpor, suggesting heterothermia is not a common thermoregulatory strategy for passerine birds.
Body Mass and Tail Girth Predict Hibernation Expression in Captive Dwarf Lemurs
TLDR
Assessment of torpor expression in captive dwarf lemurs, primates that are obligate, seasonal, and tropical hibernators, suggests that individuals optimize rather than maximize torpor according to body mass.
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References

SHOWING 1-10 OF 425 REFERENCES
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.
The Role of Energy Availability in Mammalian Hibernation: A Cost‐Benefit Approach
TLDR
It is suggested that trade‐offs between the benefits of energy conservation and the physiological costs of metabolic depression can explain both why hibernators periodically arouse from torpor and why they should use available energy to minimize the depth and duration of their torpor bouts.
Metabolic rate and body temperature reduction during hibernation and daily torpor.
  • F. Geiser
  • Biology
    Annual review of physiology
  • 2004
TLDR
The comparative analysis provided here suggests that MR reduction depends on patterns of torpor used, the state of tor porpor, and body mass, which in turn affects metabolic inhibition and energy conservation.
Hibernation energetics of free-ranging little brown bats
TLDR
New information on the energetics of hibernation in an under-represented taxon and baseline data important for understanding how white-nose syndrome, a new disease devastating populations of hibernating bats in North America, may alter the expression of hiberning in affected bats are provided.
Body mass dependent use of hibernation: why not prolong the active season, if they can?
TLDR
This study indicates that climatic conditions alone are not a good predictor of hibernation patterns or survival in hibernating species during global climate change, and concludes that predator avoidance may be an important factor influencing patterns of hiberning and torpor in mammals.
Hibernation and daily torpor in Australian mammals
TLDR
Daily and prolonged torpor in many Australian mammals appear to be opportunistic and not only important for survival of adverse seasonal conditions, but apparently also for dealing with unpredictable events such as droughts and perhaps fires and floods.
The key to winter survival: daily torpor in a small arid-zone marsupial
TLDR
This study shows that for wild stripe-faced dunnarts daily torpor is an essential mechanism for overcoming energetic challenges during winter and that torpor data obtained in the laboratory can substantially underestimate the ecological significance ofdaily torpor in the wild.
Ontogeny of metabolism, thermoregulation and torpor in the house martin Delichon u. urbica (L.) and its ecological significance
TLDR
House martins are the first passerine birds in which torpor has been found, and these adaptations might have played a role in the great success of the house martin, one of the 10–15 most abundant bird species in Europe.
THE TEMPORAL ORGANIZATION OF DAILY TORPOR AND HIBERNATION: CIRCADIAN AND CIRCANNUAL RHYTHMS
TLDR
It is reviewed whether circadian and circannual rhythms, important in the timing of biological events in active animals, also play an important role during torpor when Tb is reduced substantially and may even fall below 0°C, and there is little evidence it is significantly affected by low Tb.
How to budget metabolic energy: torpor in a small Neotropical mammal
TLDR
Investigating the thermoregulatory behavior of captive 10-g nectar feeding bats under variable ambient temperatures and feeding regimes predicted that bats would use torpor as an energy-conserving behavior under energetic constraints to point to a general capacity for torpor in tropical bats.
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