Selection of High Temperatures for Hibernation by the Pocket Mouse, Perognathus Longimembris: Ecological Advantages and Energetic Consequences

French, Alan R.

doi:10.2307/1936410

Cited by 35 publications

(18 citation statements)

References 14 publications

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“…Most of the characteristics of torpor in C. russula are consistent with those previously described for other shrews (Vogel, 1974;Frey, 1980b) and for rodents (Gaertner et al, 1973;Hill, 1975;A. R. French, 1976;Lynch et al, 1978).…”

Section: Discussionsupporting

confidence: 87%

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Ecological energetics of two European shrews: Crocidura russula and Sorex coronatus (Soricidae: Mammalia)

Genoud

1985

Journal of Zoology

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The energy strategies and especially the overwintering strategies of Crocidura russula (Croci‐durinae) and Sorex coronatus (Soricinae) were compared. These two species are sympatric over a large part of Europe, but have different ecological distributions and belong to subfamilies which have evolved under different climates. Energy budgets of wild animals were estimated by combining measurements of the metabolic rate in the laboratory (respirometry) with a time‐budget analysis in the field (radioactive tracking). Oxygen consumption was measured at different ambient temperatures (T,) and for three different behavioural states: activity, normothermic rest in a nest and torpor in a nest. These measurements were extrapolated for free‐living shrew populations by taking into account field data on morphology, behaviour, demography and climate, obtained in western Switzerland. If expressed by unit weight, the daily energy expenditure of S. coronatus, E (J g‐1) = 6459–89 T,(°C), is higher than the maximal expenditure of C. russula, E (J g‐l) = 4714–106 T,(°C). This is a consequence of the higher metabolic and activity rates of S. coronatus. However, since S. coronatus is a little lighter, individuals of both species have similar absolute expenditures. Unlike S. coronatus, overwintering C. russula can drastically lower their budget (up to 30% reduction) by the use of several saving mechanisms, e.g. torpor, nest huddling and selection of warm resting sites. But this species may reach high densities in winter and thus its population budgets may be high (up to 3000 kJ ha‐1 day‐1 for average winter conditions). The overwintering S. coronatus undergo a body size reduction, and their strictly territorial social organization maintains the population requirements at a low level (usually less than 500–600 kJ ha‐1 day‐1 for average winter conditions). The energy strategies of these two temperate shrews are correlated to their ecological distribution, and competition played an important rôle in their evolution.

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Section: Discussionsupporting

confidence: 87%

“…This discrepancy remains poorly understood, but Hanski (1 984) has found the gravimetric and respirometric methods to give similar results in several soricines. , Average insectivore energy budget after Grodzinski & Wunder (1975); ----, average rodent energy budget after French et a/. (1976).…”

Section: Daily Energy Budget In Captivity and In The$eldmentioning

confidence: 99%

Ecological energetics of two European shrews: Crocidura russula and Sorex coronatus (Soricidae: Mammalia)

Genoud

1985

Journal of Zoology

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“…In theory, even the shortest possible complete cycle of torpor or hypothermia may result in significant energy savings (Tucker 1966;Bartholomew 1972;French 1976), but my observations revealed very little circadian body temperature variation and no indication of hypothermia or torpor. This stability of Tb is probably due in large part to the relatively large size and well-insulated nests of arctic ground squirrels, which prevent them from cycling Tb rapidly enough for selection to favor the evolution of daily torpor.…”

Section: Temperature Regulationmentioning

confidence: 68%

Standard operative temperatures and cost of thermoregulation in the arctic ground squirrel, Spermophilus undulatus

Chappell

1981

Oecologia

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Body temperatures (T ) and daily activity patterns of free-living arctic ground squirrells (Spermophilus undulatus) were determined via telemetry at a field site in northern Alaska. Simultaneous measurements were made of ambient temperature (T), wind speed (V), and incident solar radiation. The operative environmental temperature (T ) for ground squirrels was obtained from fur-covered, thin metal taxidermic models of the animals. Standard operative temperature (T), a comparative index of heat flow, was calculated from T , V, and laboratory measurements of thermal conductivity.During the period of the study (August), S. undulatus were active for about 14 h per day (06.00 to 20.00 h). T was high throughout the daily cycle, averaging 38-39°C. Circadian variations in T were slight; average T values dropped <1°C at night. Daytime T fluctuations were not closely correlated to activity or to changes in environmental conditions. Air temperatures during the study were low, usually between 10 and 15°C during the day. However, T in exposed areas was normally higher, even though skies were generally overcast. During periods of sunshine, T may be as high as 34°C. The absence of nocturnal activity may result from increased costs of thermoregulation at night, which sharply reduces foraging efficiency. The high and stable body temperatures of S. undulatus probably result from thermoneutral daytime T, low activity levels, and the use of well-insulated nests.

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“…Changes in torpor pattern are likely to influence other facets of hibernation ecology. Although there are clear benefits to torpor, food manipulation experiments demonstrate that hibernators of some species will remain euthermic if the food supply allows it (Brown & Bartholomew 1969; French 1976; Reichman & Brown 1979). This may be because hibernation increases vulnerability to predation (Young 1990).…”

Section: Discussionmentioning

confidence: 99%

Does immune challenge affect torpor duration?

Burton

Reichman

1999

Functional Ecology

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Summary 1.Hibernation may alter the relationship between pathogens and their hosts; low host temperatures can prevent pathogen replication. Therefore, manipulating the timing and duration of torpor bouts could allow animals to gain an advantage over pathogens. 2. Thirty-two Turkish Hamsters (Mesocricetus brandti) were placed in short-day, cold conditions. After 10 weeks, 20 animals were challenged with an antigen to simulate a pathogen infection. Ten of these animals were returned to the cold ('cold-challenged'). The other 10 animals were placed in warm conditions ('warm-challenged'). Twelve animals received saline injections and were returned to the cold ('cold-control'). Coldchallenged animals spent significantly more time in torpor than did cold-control animals. 3. After 6·5 weeks, all animals were housed in warm conditions and ceased torpor. Both cold-challenged and warm-challenged animals received a second injection of antigen. There was no correlation between time spent euthermic and level of secondary humoral response of cold-challenged animals. The secondary humoral response of the cold-challenged animals was significantly lower than that of warm-challenged animals. 4. In this study immune status influenced torpor duration, and torpor caused immunosuppression. Hibernators may manipulate body temperature in order to combat pathogens while their own immune systems are suppressed.

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Selection of High Temperatures for Hibernation by the Pocket Mouse, Perognathus Longimembris: Ecological Advantages and Energetic Consequences

Cited by 35 publications

References 14 publications

Ecological energetics of two European shrews: Crocidura russula and Sorex coronatus (Soricidae: Mammalia)

Ecological energetics of two European shrews: Crocidura russula and Sorex coronatus (Soricidae: Mammalia)

Standard operative temperatures and cost of thermoregulation in the arctic ground squirrel, Spermophilus undulatus

Does immune challenge affect torpor duration?

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