scholarly journals Surviving winter on the Qinghai-Tibetan Plateau: Pikas suppress energy demands and exploit yak feces to survive winter

2021 ◽  
Vol 118 (30) ◽  
pp. e2100707118
Author(s):  
John R. Speakman ◽  
Qingsheng Chi ◽  
Łukasz Ołdakowski ◽  
Haibo Fu ◽  
Quinn E. Fletcher ◽  
...  
Keyword(s):  
Body Temperature ◽  
Tibetan Plateau ◽  
Mammalian Species ◽  
Resting Metabolic Rate ◽  
Stomach Contents ◽  
Low Oxygen ◽  
Plateau Pika ◽  
Ambient Temperatures ◽  
Energy Demands ◽  
In The Wild

The Qinghai-Tibetan Plateau, with low precipitation, low oxygen partial pressure, and temperatures routinely dropping below −30 °C in winter, presents several physiological challenges to its fauna. Yet it is home to many endemic mammalian species, including the plateau pika (Ochotona curzoniae). How these small animals that are incapable of hibernation survive the winter is an enigma. Measurements of daily energy expenditure (DEE) using the doubly labeled water method show that pikas suppress their DEE during winter. At the same body weight, pikas in winter expend 29.7% less than in summer, despite ambient temperatures being approximately 25 °C lower. Combined with resting metabolic rates (RMRs), this gives them an exceptionally low metabolic scope in winter (DEE/RMRt = 1.60 ± 0.30; RMRt is resting metabolic rate at thermoneutrality). Using implanted body temperature loggers and filming in the wild, we show that this is achieved by reducing body temperature and physical activity. Thyroid hormone (T3 and T4) measurements indicate this metabolic suppression is probably mediated via the thyroid axis. Winter activity was lower at sites where domestic yak (Bos grunniens) densities were higher. Pikas supplement their food intake at these sites by eating yak feces, demonstrated by direct observation, identification of yak DNA in pika stomach contents, and greater convergence in the yak/pika microbiotas in winter. This interspecific coprophagy allows pikas to thrive where yak are abundant and partially explains why pika densities are higher where domestic yak, their supposed direct competitors for food, are more abundant.

A songbird adjusts its heart rate and body temperature in response to season and fluctuating daily conditions

2021 ◽  
Vol 376 (1830) ◽  
pp. 20200213 ◽  
Author(s):  
Nils Linek ◽  
Tamara Volkmer ◽  
J. Ryan Shipley ◽  
Cornelia W. Twining ◽  
Daniel Zúñiga ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Environmental Conditions ◽  
Field Studies ◽  
Weather Extremes ◽  
Ambient Temperatures ◽  
In The Wild ◽  
Radio Transmitters ◽  
Save Energy ◽  
Free Ranging

In a seasonal world, organisms are continuously adjusting physiological processes relative to local environmental conditions. Owing to their limited heat and fat storage capacities, small animals, such as songbirds, must rapidly modulate their metabolism in response to weather extremes and changing seasons to ensure survival. As a consequence of previous technical limitations, most of our existing knowledge about how animals respond to changing environmental conditions comes from laboratory studies or field studies over short temporal scales. Here, we expanded beyond previous studies by outfitting 71 free-ranging Eurasian blackbirds ( Turdus merula ) with novel heart rate and body temperature loggers coupled with radio transmitters, and followed individuals in the wild from autumn to spring. Across seasons, blackbirds thermoconformed at night, i.e. their body temperature decreased with decreasing ambient temperature, but not so during daytime. By contrast, during all seasons blackbirds increased their heart rate when ambient temperatures became colder. However, the temperature setpoint at which heart rate was increased differed between seasons and between day and night. In our study, blackbirds showed an overall seasonal reduction in mean heart rate of 108 beats min −1 (21%) as well as a 1.2°C decrease in nighttime body temperature. Episodes of hypometabolism during cold periods likely allow the birds to save energy and, thus, help offset the increased energetic costs during the winter when also confronted with lower resource availability. Our data highlight that, similar to larger non-hibernating mammals and birds, small passerine birds such as Eurasian blackbirds not only adjust their heart rate and body temperature on daily timescales, but also exhibit pronounced seasonal changes in both that are modulated by local environmental conditions such as temperature. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.

Effect of age on cold acclimation in rats: metabolic and behavioral responses

1991 ◽  
Vol 260 (2) ◽  
pp. R284-R289 ◽  
Author(s):  
T. L. Owen ◽  
R. L. Spencer ◽  
S. P. Duckles
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Cold Acclimation ◽  
Cold Exposure ◽  
Resting Metabolic Rate ◽  
Age Groups ◽  
Behavioral Responses ◽  
Mortality And Morbidity ◽  
Ambient Temperatures ◽  
Reduced Body

To determine whether senescence affects the metabolic and behavioral responses of rats to chronic cold exposure, 8- and 22-mo-old male Fischer 344 rats were studied before and after 6 wk of cold (6-10 degrees C) exposure. Measurements of body weight, food consumption, oxygen consumption, body temperature, and ambient temperature selection in a thermocline (7-37 degrees C linear gradient) were made at regular intervals throughout the acclimation period. Before acclimation, age groups differed significantly only by weight. During acclimation, older rats had increased mortality and morbidity below 10 degrees C. After acclimation at 10 degrees C, younger and older rats both selected cooler ambient temperatures (7 and 5 degrees C cooler than preacclimation, respectively), and older rats had a significantly greater decrease in body temperature in the thermocline. Both age groups increased resting metabolic rate at 25 degrees C with cold acclimation (16.5 and 10% increase for younger and older rats, respectively). This study indicates distinct differences in metabolic and behavioral responses of younger and older rats to cold acclimation. Chronic cold exposure is detrimental to thermoregulatory function in older rats, since it is not as effective in stimulating sustained increases in metabolic rate in older rats as in young adults and it leads to a preference for cooler ambient temperatures, resulting in increased heat loss and reduced body temperature.

scholarly journals The relationship between fasting-induced torpor, sleep and waking in laboratory mice

SLEEP ◽  
2021 ◽  
Author(s):  
Yi-Ge Huang ◽  
Sarah J Flaherty ◽  
Carina A Pothecary ◽  
Russell G Foster ◽  
Stuart N Peirson ◽  
...  
Keyword(s):  
Body Temperature ◽  
Rem Sleep ◽  
Brain Activity ◽  
Mammalian Species ◽  
Nrem Sleep ◽  
Laboratory Mice ◽  
State Classification ◽  
Metabolic Suppression ◽  
The Relationship ◽  
Electroencephalogram Eeg

Abstract Study objectives Torpor is a regulated and reversible state of metabolic suppression used by many mammalian species to conserve energy. Whereas the relationship between torpor and sleep has been well-studied in seasonal hibernators, less is known about the effects of fasting-induced torpor on states of vigilance and brain activity in laboratory mice. Methods Continuous monitoring of electroencephalogram (EEG), electromyogram (EMG) and surface body temperature was undertaken in adult, male C57BL/6 mice over consecutive days of scheduled restricted feeding. Results All animals showed bouts of hypothermia that became progressively deeper and longer as fasting progressed. EEG and EMG were markedly affected by hypothermia, although the typical electrophysiological signatures of NREM sleep, REM sleep and wakefulness enabled us to perform vigilance-state classification in all cases. Consistent with previous studies, hypothermic bouts were initiated from a state indistinguishable from NREM sleep, with EEG power decreasing gradually in parallel with decreasing surface body temperature. During deep hypothermia, REM sleep was largely abolished, and we observed shivering-associated intense bursts of muscle activity. Conclusions Our study highlights important similarities between EEG signatures of fasting-induced torpor in mice, daily torpor in Djungarian hamsters and hibernation in seasonally-hibernating species. Future studies are necessary to clarify the effects on fasting-induced torpor on subsequent sleep.

scholarly journals On the modulation and maintenance of hibernation in captive dwarf lemurs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marina B. Blanco ◽  
Lydia K. Greene ◽  
Robert Schopler ◽  
Cathy V. Williams ◽  
Danielle Lynch ◽  
...  
Keyword(s):  
Food Restriction ◽  
Metabolic Disorders ◽  
Biological Rhythms ◽  
Food Ingestion ◽  
Ambient Temperatures ◽  
In Captivity ◽  
In The Wild ◽  
Cheirogaleus Medius ◽  
Save Energy ◽  
Metabolic Strategies

AbstractIn nature, photoperiod signals environmental seasonality and is a strong selective “zeitgeber” that synchronizes biological rhythms. For animals facing seasonal environmental challenges and energetic bottlenecks, daily torpor and hibernation are two metabolic strategies that can save energy. In the wild, the dwarf lemurs of Madagascar are obligate hibernators, hibernating between 3 and 7 months a year. In captivity, however, dwarf lemurs generally express torpor for periods far shorter than the hibernation season in Madagascar. We investigated whether fat-tailed dwarf lemurs (Cheirogaleus medius) housed at the Duke Lemur Center (DLC) could hibernate, by subjecting 8 individuals to husbandry conditions more in accord with those in Madagascar, including alternating photoperiods, low ambient temperatures, and food restriction. All dwarf lemurs displayed daily and multiday torpor bouts, including bouts lasting ~ 11 days. Ambient temperature was the greatest predictor of torpor bout duration, and food ingestion and night length also played a role. Unlike their wild counterparts, who rarely leave their hibernacula and do not feed during hibernation, DLC dwarf lemurs sporadically moved and ate. While demonstrating that captive dwarf lemurs are physiologically capable of hibernation, we argue that facilitating their hibernation serves both husbandry and research goals: first, it enables lemurs to express the biphasic phenotypes (fattening and fat depletion) that are characteristic of their wild conspecifics; second, by “renaturalizing” dwarf lemurs in captivity, they will emerge a better model for understanding both metabolic extremes in primates generally and metabolic disorders in humans specifically.

scholarly journals Diurnal Body Temperature and Rate of Passage of Loggers in Lions

Animals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1388
Author(s):  
Ted Friend ◽  
Giulia Corsini ◽  
Vincent Manero ◽  
Raffaella Cocco
Keyword(s):  
Body Temperature ◽  
Time Frame ◽  
Heat Lamp ◽  
Future Studies ◽  
Ambient Temperatures ◽  
Diurnal Patterns ◽  
Data Loggers ◽  
The Mean ◽  
African Lions ◽  
Circadian Patterns

The documentation of diurnal patterns in body temperature in lions could be important because disruption of circadian patterns can be a useful measure of distress. This study quantified changes in body temperature of seven African lions (Panthera leo) at 5 min intervals during cold conditions from noon until the ingested body temperature loggers were expelled the next day. Thirteen loggers were fed to 11 lions during their daily noon feeding, while ambient temperatures were also recorded using six data loggers. The lions had continuous access to their dens and exercise pens during the day but were restricted to their heavily bedded dens that also contained a heat lamp from 23:00 until 08:00 the next day. Body temperatures averaged 37.95 ± 0.42 °C at 15:50, and 36.81 ± 0.17 °C at 06:50 the next day, 30 min before the first loggers passed from a lion, and were significantly different (t-test, t = 8.09, df = 6, p < 0.0003). The mean duration for the time of passage was 22 ± 2.69 (h ± SD), so future studies using the noninvasive feeding of temperature loggers need to consider that time frame.

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

Limits to sustained energy intake

2001 ◽  
Vol 204 (11) ◽  
pp. 1947-1956 ◽  
Author(s):  
M. S. Johnson ◽  
S. C. Thomson ◽  
J. R. Speakman
Keyword(s):  
Food Intake ◽  
Energy Intake ◽  
Litter Size ◽  
Resting Metabolic Rate ◽  
Control Group ◽  
Lower Mass ◽  
Daily Food Intake ◽  
Energy Demands ◽  
Daily Food ◽  
Pregnancy And Lactation

SUMMARYTo determine whether mice were limited in their capacity to absorb energy during late lactation, we attempted to increase the energy burden experienced by a group of female mice during late lactation by mating them at the postpartum oestrus, hence combining the energy demands of pregnancy and lactation. These experimental mice were therefore concurrently pregnant and lactating in their first lactation, and were followed through a normal second lactation. In a control group, females also underwent two lactations but sequentially, with the second mating after the first litter had been weaned. Maternal mass and food intake were measured throughout the first lactation, second pregnancy and second lactation. Maternal resting metabolic rate (RMR) was measured prior to the first mating and then at the peak of both the first and second lactations. Litter size and litter mass were also measured throughout both lactations. In the first lactation, experimental mice had a lower mass-independent RMR (F1,88=5.15, P=0.026) and raised significantly heavier pups (t=2.77, d.f.=32, P=0.0093) than the control mice. Experimental mice delayed implantation at the start of the second pregnancy. The extent of the delay was positively related to litter size during the first lactation (F1,19=4.58, P=0.046) and negatively related to mean pup mass (F1,19=5.78, P=0.027) in the first lactation. In the second lactation, the experimental mice gave birth to more (t=2.75, d.f.=38, P=0.0092) and lighter (t=−5.01, d.f.=38, P&lt;0.0001) pups than did the controls in their second lactation. Maternal asymptotic daily food intake of control mice in the second lactation was significantly higher (t=−4.39, d.f.=37, P=0.0001) than that of the experimental mice and higher than that of controls during their first lactation. Despite the added burden on the experimental females during their first lactation, there was no increase in their food intake, which suggested that they might be limited by their capacity to absorb energy. However, control females appeared to be capable of increasing their asymptotic food intake beyond the supposed limits estimated previously, suggesting that the previously established limit was not a fixed central limitation on food intake. As RMR increased in parallel with the increase in food intake during the second lactation of control mice, the sustained energy intake remained at around 7.0×RMR.

Development of temperature regulation in young birds: evidence for a vocal regulatory mechanism in two species of gulls (Laridae)

1994 ◽  
Vol 72 (3) ◽  
pp. 427-432 ◽  
Author(s):  
Myra O. Wiebe ◽  
Roger M. Evans
Keyword(s):  
Body Temperature ◽  
Temperature Regulation ◽  
Regulatory Mechanism ◽  
Mammalian Species ◽  
Larus Argentatus ◽  
Herring Gulls ◽  
Stage Of Development ◽  
Larus Delawarensis ◽  
Regulate Body Temperature

Endothermic thermoregulation is absent in birds until after hatching, and usually requires several hours or days to become fully functional in the young. Cold-induced vocalizations that elicit brooding by a cooperative parent or surrogate constitute an additional thermoregulatory mechanism potentially available to neonates of some avian and probably some mammalian species. We show that newly hatched ring-billed gulls (Larus delawarensis) and herring gulls (Larus argentatus) exposed in the laboratory to moderate chilling (20 °C) had a significantly improved ability to regulate body temperature when rewarmed (34 °C) for brief, 4-min periods in response to cold-induced vocalizations. Spontaneous calling by unchilled yoked controls was ineffective in maintaining body temperature. When chicks reached 3 days of age, vocally regulated temperaturee did not differ from that attained by thermogenesis, but vocally induced periods of rewarming reduced the duration of temperature challenge. The ability to regulate body temperature through vocalizations precedes the development of endothermy in gulls and other species so far examined, and in some species extends functional thermoregulation back to the late embryonic (pipped egg) stage of development.

scholarly journals Body Temperatures in Some Australian Mammals II.Peramelidae

1962 ◽  
Vol 15 (2) ◽  
pp. 386 ◽  
Author(s):  
PR Morrison
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Active Phase ◽  
Temperature Measurements ◽  
Temperature Cycle ◽  
Body Temperatures ◽  
Ambient Temperatures ◽  
Diurnal Temperature

Body temperature measurements on the short-nosed bandicoot (Thylacis obeaulus) have shown a nocturnal cycle with a range of 1� 2�C and a short active phase at 2200-0400 hr. The bilby or rabbit bandicoot (Macrotis lagoti8) had a sharply defined temperature cycle, with a range of almost 3�C after several months of captivity, during which the day-time resting temperature was progressively lowered from 36� 4 to 34� 2�C. Forced activity raised the diurnal temperature substantially but not to the nocturnal level. Forced activity did not raise the nocturnal level which was similar in the two species (37' O�C). Both species could regulate effectively at an ambient temperature of 5�C, but only Thylaci8 showed regulation at ambient temperatures of between 30 and 40�C.

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