Seasonal pattern and energetics of short daily torpor in the Djungarian hamster, Phodopus sungorus

Heldmaier, Gerhard; Steinlechner, Stephan

doi:10.1007/bf00347975

Cited by 180 publications

(99 citation statements)

References 13 publications

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“…The resting T b of 34.7°C at T a 15°C was similar to that previously reported under similar thermal conditions (Ruf et al, 1993) and so was the decrease of RMR with T a (Heldmaier and Steinlechner, 1981), although our values were slightly lower. The torpor patterns of hamsters observed here were somewhat unusual because hamsters often expressed more than one torpor bout per day, but it is known that multiple bouts per day may be used by the species, especially when food is withheld (Steinlechner et al, 1986;Diedrich et al, 2015), as in our measurements.…”

Section: Discussionsupporting

confidence: 91%

“…3). With regard to physiological variables during steady-state torpor, the minimum T b of about 22°C was similar to that measured under similar thermal conditions (Heldmaier and Steinlechner, 1981;Diedrich et al, 2015). However, the mean minimum TMR measured here was only 34% of that measured by Heldmaier and Steinlechner (1981), but similar to those reported more recently at ∼1/3 of BMR (Diedrich et al, 2015;Ruf and Geiser, 2015).…”

Section: Discussionsupporting

confidence: 90%

“…White winter-acclimated individuals enter spontaneous daily torpor (food ad libitum), whereas brown summer-acclimated animals do not (Heldmaier and Steinlechner, 1981;Ruf et al, 1993;Geiser et al, 2013). Little is known about the ecology and biology of the species in the wild, but they live in steppes of central Asia that receive substantial amounts of sun in winter and they do not restrict activity to the night (Flint, 1966), as is also the case in captivity, especially when exposed to low T a (Heldmaier et al, 1989;Ruf et al, 1991;Müller et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Basking hamsters reduce resting metabolism, body temperature and energy costs during rewarming from torpor

Geiser

Gasch

Bieber

et al. 2016

Journal of Experimental Biology

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Basking can substantially reduce thermoregulatory energy expenditure of mammals. We tested the hypothesis that the largely white winter fur of hamsters (Phodopus sungorus), originating from Asian steppes, may be related to camouflage to permit sun basking on or near snow. Winter-acclimated hamsters in our study were largely white and had a high proclivity to bask when resting and torpid. Resting hamsters reduced metabolic rate (MR) significantly (>30%) when basking at ambient temperatures (T a ) of ∼15 and 0°C. Interestingly, body temperature (T b ) also was significantly reduced from 34.7±0.6°C (T a 15°C, not basking) to 30.4±2.0°C (T a 0°C, basking), which resulted in an extremely low (<50% of predicted) apparent thermal conductance. Induced torpor (food withheld) during respirometry at T a 15°C occurred on 83.3±36.0% of days and the minimum torpor MR was 36% of basal MR at an average T b of 22.0±2.6°C; movement to the basking lamp occurred at T b <20.0°C. Energy expenditure for rewarming was significantly reduced (by >50%) during radiant heat-assisted rewarming; however, radiant heat per se without an endogenous contribution by animals did not strongly affect metabolism and T b during torpor. Our data show that basking substantially modifies thermal energetics in hamsters, with a drop of resting T b and MR not previously observed and a reduction of rewarming costs. The energy savings afforded by basking in hamsters suggest that this behaviour is of energetic significance not only for mammals living in deserts, where basking is common, but also for P. sungorus and probably other cold-climate mammals.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Basking hamsters reduce resting metabolism, body temperature and energy costs during rewarming from torpor

Geiser

Gasch

Bieber

et al. 2016

Journal of Experimental Biology

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“…More importantly, however, the aardwolf's size may preclude it from lowering its T b below 31-33 º C. Although a number of medium-to large-sized mammals undergo hypothermia (e.g. Heldmaier & Steinlechner, 1981;Bakko & Nahorniak, 1986;Wang & Holowyk, 1988), this physiological adaptation is typical of small mammals where the size limit to hypothermia is set by the costs of rewarming which is directly proportional to body mass, so the larger the animal the greater the costs (Prothero & Jurgens, 1986;Geiser, 1988).…”

Section: Body Temperaturementioning

confidence: 99%

Aardwolf adaptations: a review

Anderson¹

2004

Transactions of the Royal Society of South Africa

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The aardwolf Proteles cristatus has developed a number of anatomical and morphological adaptations for feeding on its termite prey. These adaptations preclude the aardwolf from feeding on other, larger (vertebrate) prey, especially during the winter months, when the T a drops below 9 º C and when Trinervitermes termites are largely unavailable. Winter is therefore a stressful period for aardwolves, as evidenced by increased juvenile mortality, a 20% decline in body mass and depletion of subcutaneous fat reserves. The aardwolf uses both physiological and behavioural means to overcome this period of food stress. An increased period is spent underground in the thermally-stable environment of the den. Den sharing is more common in the winter months and social thermoregulation may result in energy savings. While inactive the aardwolf lowers its T b (to an average of 34.1+1.6 º C during the middle of the inactive period during winter) and in some individuals this results in energy savings of up to 18%. Seasonal changes in pelage density and thermal conductance allow for more passive heat transfer during summer and improved heat retention during winter. Laboratory and field measurements of metabolic rate showed that the aardwolf has a low BMR and a low FMR (between 40 and 78% of that predicted by allometric equations). The aardwolf's metabolic rate is 11% lower during the winter months, resulting in reduced energy requirements during the period of limited food availability. Evaporative water loss rates are low, further reduced during the winter months, adaptations to survive in a desert environment and on a seasonally-unavailable food source. The aardwolf is therefore well adapted to feed on a diet of Trinervitermes termites, a food niche that has been largely unexploited by other animals, and it uses various ecological, behavioural and physiological adaptations to cope with this seasonally unavailable food source.

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“…Many morphological and physiological adaptations like reduced m b , white pelage and daily torpor reduce its total energy requirements in winter (Figala et al, 1973;Hoffmann, 1973;Heldmaier and Steinlechner, 1981a;Heldmaier and Steinlechner, 1981b;Ruf and Heldmaier, 1992;Ruf et al, 1993;Kuhlmann et al, 2003). Daily torpor occurs as the last response to winter conditions, after a decrease in m b and moulting (Heldmaier and Steinlechner, 1981a).…”

Section: Introductionmentioning

confidence: 99%

Social thermoregulation and torpor in the Siberian hamster

Jefimow

Głabska

Wojciechowski

2011

Journal of Experimental Biology

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SUMMARYSocial thermoregulation and huddling bring about energy benefits to animals sharing a nest because of the smaller surface-tovolume ratio of a huddle and the higher local temperature in the nest. We tested whether living in groups and huddling affect daily torpor, metabolic rate and seasonal changes in the body mass of a small heterothermic rodent, the Siberian hamster (Phodopus sungorus), housed under semi-natural conditions both singly and in groups of four litter-mates. We predicted that in hamsters housed in groups: (1) synchronized torpor bouts would be longer and deeper than non-synchronized ones but shallower than in solitary hamsters, (2) seasonal variations in metabolic rate would be lower than in solitary hamsters, and (3) the winter decrease in body mass would be smaller in grouped than in singly housed hamsters. We found that group housing led to a smaller decrease in body mass in winter, and affected the length and depth of daily torpor. In group-living hamsters more than 50% of all torpor episodes were synchronized and torpid animals were often found in huddles formed of all cage-mates. The longest and deepest torpor bouts in groups were recorded when all animals in a group entered torpor simultaneously. Although the minimum body temperature during torpor was higher, torpor duration was slightly longer than in solitary hamsters. We did not record significant differences in the body mass-adjusted rate of oxygen consumption between solitary and grouped animals, either in the cold or at the lower critical temperature. We conclude that social thermoregulation enables maintenance of a larger body mass, and thus a larger body fat content, which can ensure better body condition at the beginning of the reproductive season.

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Seasonal pattern and energetics of short daily torpor in the Djungarian hamster, Phodopus sungorus

Cited by 180 publications

References 13 publications

Basking hamsters reduce resting metabolism, body temperature and energy costs during rewarming from torpor

Basking hamsters reduce resting metabolism, body temperature and energy costs during rewarming from torpor

Aardwolf adaptations: a review

Social thermoregulation and torpor in the Siberian hamster

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