Seasonal variation in the foraging activity of desert argali (Ovis ammon) in Mongolia

2019 ◽  
Vol 97 (10) ◽  
pp. 931-939 ◽  
Author(s):  
Barry Rosenbaum ◽  
Richard P. Reading ◽  
Garam Tsogtjargal ◽  
Sukh Amgalanbaatar ◽  
Sebastien Comte
Keyword(s):  
Heat Dissipation ◽  
Ambient Temperatures ◽  
Energy Demands ◽  
Animal Activity ◽  
Time Minimization ◽  
Physiological Demands ◽  
Energy Maximization ◽  
Foraging Pattern ◽  
Ovis Ammon ◽  
Body Heat

Debate remains whether energy maximization or time minimization strategies best explain foraging in ungulates. It has also been hypothesized that the capacity of an animal to dissipate body heat regulates animal activity. We investigated these hypotheses while measuring the daily activity of desert argali (Ovis ammon (Linnaeus,1758)) for 12 months and relating the activity pattern to environmental seasonality. We found significant seasonal cycles in argali activity, with the greatest proportion of daytime in winter spent foraging and the greatest proportion of daytime in summer spent bedding. Consistent with an energy maximization strategy, argali reduced all behaviors during the winter in favor of foraging, compensating for the increased energy demands of winter at a time of low forage quality. Consistent with a time minimization strategy, argali in summer significantly reduced foraging and spent more time bedding in shaded areas to avoid hyperthermia due to high ambient temperatures. Both optimal foraging and heat dissipation can be used to explain the observed foraging pattern. Foraging behavior in argali is best described by the extent to which the animals schedule their activities to meet their physiological demands, the way these demands are affected by environmental variables, and the time that is available to accomplish them.

scholarly journals Heat dissipation in subterranean rodents: the role of body region and social organisation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
František Vejmělka ◽  
Jan Okrouhlík ◽  
Matěj Lövy ◽  
Gabriel Šaffa ◽  
Eviatar Nevo ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Heat Dissipation ◽  
Ventral Surface ◽  
Body Region ◽  
Subterranean Rodents ◽  
Ambient Temperatures ◽  
Social Species ◽  
Body Regions ◽  
Body Heat ◽  
Solitary Species

AbstractThe relatively warm and very humid environment of burrows presents a challenge for thermoregulation of its mammalian inhabitants. It was found that African mole-rats dissipate body heat mainly through their venter, and social mole-rats dissipate more body heat compared to solitary species at lower temperatures. In addition, the pattern of the ventral surface temperature was suggested to be homogeneous in social mole-rats compared to a heterogeneous pattern in solitary mole-rats. To investigate this for subterranean rodents generally, we measured the surface temperatures of seven species with different degrees of sociality, phylogeny, and climate using infrared thermography. In all species, heat dissipation occurred mainly through the venter and the feet. Whereas the feet dissipated body heat at higher ambient temperatures and conserved it at lower ambient temperatures, the ventral surface temperature was relatively high in all temperatures indicating that heat dissipation to the environment through this body region is regulated mainly by behavioural means. Solitary species dissipated less heat through their dorsum than social species, and a tendency for this pattern was observed for the venter. The pattern of heterogeneity of surface temperature through the venter was not related to sociality of the various species. Our results demonstrate a general pattern of body heat exchange through the three studied body regions in subterranean rodents. Besides, isolated individuals of social species are less able to defend themselves against low ambient temperatures, which may handicap them if staying alone for a longer period, such as during and after dispersal events.

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

Effect of heating rate on evaporative heat loss in the microwave-exposed mouse

1982 ◽  
Vol 53 (2) ◽  
pp. 316-323 ◽  
Author(s):  
C. J. Gordon
Keyword(s):  
Body Temperature ◽  
Heat Loss ◽  
Heat Dissipation ◽  
Dew Point ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Heat Absorption ◽  
Deep Body Temperature ◽  
The Difference ◽  
Body Heat

Male CBA/J mice were administered heat loads of 0–28 J X g-1 at specific absorption rates (SARs) of either 47 or 93 W X kg-1 by exposure to 2,450-MHz microwave radiation at an ambient temperature of 30 degrees C while evaporative heat loss (EHL) was continuously monitored with dew-point hygrometry. At an SAR of 47 W X kg-1 a threshold heat load of 10.5 J X g-1 had to be exceeded before EHL increased. An approximate doubling of SAR to 93 W X kg-1 reduced the threshold to 5.2 J X g-1. Above threshold the slopes of the regression lines were 1.15 and 0.929 for the low- and high-SAR groups, respectively. Thus the difference in threshold and not slope attributes to the significant increase in EHL when mice are exposed at a high SAR (P less than 0.02). In separate experiments a SAR of 47 W X kg-1 raised the deep body temperature of anesthetized mice at a rate of 0.026 degrees C X s-1, whereas 93 W X kg-1 raised temperature at 0.049 degrees C X s-1. Hence the sensitivity of the EHL mode of heat dissipation is directly proportional to the rate of heat absorption and to the rate of rise in body temperature. These data contradict the notion that mammals have control over whole-body heat exchange only (i.e., thermoregulation) but instead indicate that the EHL system is highly responsive to the rate of heat absorption (i.e., temperature regulation).

scholarly journals Testing the heat dissipation limit theory in a breeding passerine

2018 ◽  
Vol 285 (1878) ◽  
pp. 20180652 ◽  
Author(s):  
Jan-Åke Nilsson ◽  
Andreas Nord
Keyword(s):  
Heat Dissipation ◽  
Work Rate ◽  
Body Temperatures ◽  
Limit Theory ◽  
Ambient Temperatures ◽  
Metabolic Heat ◽  
Thermal Window ◽  
Future Reproduction ◽  
Maximum Work ◽  
Males And Females

The maximum work rate of animals has recently been suggested to be determined by the rate at which excess metabolic heat generated during work can be dissipated (heat dissipation limitation (HDL) theory). As a first step towards testing this theory in wild animals, we experimentally manipulated brood size in breeding marsh tits ( Poecile palustris ) to change their work rate. Parents feeding nestlings generally operated at above-normal body temperatures. Body temperature in both males and females increased with maximum ambient temperature and with manipulated work rate, sometimes even exceeding 45°C, which is close to suggested lethal levels for birds. Such high body temperatures have previously only been described for birds living in hot and arid regions. Thus, reproductive effort in marsh tits may potentially be limited by the rate of heat dissipation. Females had lower body temperatures, a possible consequence of their brood patch serving as a thermal window facilitating heat dissipation. Because increasing body temperatures are connected to somatic costs, we suggest that the HDL theory may constitute a possible mediator of the trade-off between current and future reproduction. It follows that globally increasing, more stochastic, ambient temperatures may restrict the capacity for sustained work of animals in the future.

Temperature regulation

2017 ◽  
Author(s):  
Bareket Falk ◽  
Raffy Dotan
Keyword(s):  
Body Temperature ◽  
Children And Adolescents ◽  
Temperature Regulation ◽  
Heat Dissipation ◽  
Epidemiological Data ◽  
Skin Surface ◽  
Neutral Zone ◽  
Sweat Loss ◽  
Ambient Temperatures ◽  
Dry Heat

Under all but the most extreme environmental heat conditions, children control their body temperature (at rest and during exercise) as well as adults. Children, however, use a different thermoregulatory strategy. Compared with adults, children rely more on dry heat dissipation and less on evaporative cooling (sweating). Their larger skin surface-area relative to mass does put children at increasing disadvantage, relative to adults, as ambient temperatures rise above skin temperature. Similarly, they become increasingly disadvantaged upon exposure to decreasing temperatures below the thermo-neutral zone. Like adults, children inadvertently dehydrate while exercising in hot conditions and are often hypohydrated, even before exercise, and their core temperature rises considerably more than adults in response to a given fluid (sweat) loss, which may put them at higher risk for heat-related injury. However, epidemiological data show rates of both heat- and cold-related injuries among children and adolescents as similar or lower than at any other age.

scholarly journals The contribution of the mouse tail to thermoregulation is modest

2020 ◽  
Vol 319 (2) ◽  
pp. E438-E446
Author(s):  
Vojtěch Škop ◽  
Naili Liu ◽  
Juen Guo ◽  
Oksana Gavrilova ◽  
Marc L. Reitman
Keyword(s):  
Metabolic Rate ◽  
Heat Loss ◽  
Heat Dissipation ◽  
Whole Body ◽  
Total Heat Loss ◽  
Brown Adipose ◽  
Adrenergic Antagonist ◽  
Similar Body ◽  
And Control ◽  
Body Heat

Understanding mouse thermal physiology informs the usefulness of mice as models of human disease. It is widely assumed that the mouse tail contributes greatly to heat loss (as it does in rat), but this has not been quantitated. We studied C57BL/6J mice after tail amputation. Tailless mice housed at 22°C did not differ from littermate controls in body weight, lean or fat content, or energy expenditure. With acute changes in ambient temperature from 19 to 39°C, tailless and control mice demonstrated similar body temperatures (Tb), metabolic rates, and heat conductances and no difference in thermoneutral point. Treatment with prazosin, an α1-adrenergic antagonist and vasodilator, increased tail temperature in control mice by up to 4.8 ± 0.8°C. Comparing prazosin treatment in tailless and control mice suggested that the tail’s contribution to total heat loss was a nonsignificant 3.4%. Major heat stress produced by treatment at 30°C with CL316243, a β3-adrenergic agonist, increased metabolic rate and Tb and, at a matched increase in metabolic rate, the tailless mice showed a 0.72 ± 0.14°C greater Tb increase and 7.6% lower whole body heat conductance. Thus, the mouse tail is a useful biomarker of vasodilation and thermoregulation, but in our experiments contributes only 5–8% of whole body heat dissipation, less than the 17% reported for rat. Heat dissipation through the tail is important under extreme scenarios such as pharmacological activation of brown adipose tissue; however, non-tail contributions to heat loss may have been underestimated in the mouse.

Effects of hypoxia and ambient temperature on gaseous metabolism of newborn rats

1992 ◽  
Vol 263 (2) ◽  
pp. R267-R272 ◽  
Author(s):  
J. P. Mortola ◽  
A. Dotta
Keyword(s):  
Heat Dissipation ◽  
Metabolic Response ◽  
Whole Body ◽  
Newborn Rats ◽  
Open Flow ◽  
Ambient Temperatures ◽  
Limited Effectiveness ◽  
Old Rats ◽  
Per Se ◽  
Maintain Body Temperature

Whole body metabolic rate was measured by open-flow respirometry in 2-day-old rats at ambient temperatures (Ta) between 40 and 15 degrees C, changed at a rate of 0.5 degrees C/min, during normoxia or hypoxia (10% inspired O2). In normoxia, the thermoneutral range was found to be very narrow, at around 33 degrees C, suggesting a limited effectiveness in the mechanisms controlling heat dissipation. At lower or higher Ta, metabolism was at first increased; this increase could be maintained for at least 30 min at 30 and 35 degrees C, i.e., slightly below or above thermoneutrality, but it was not maintained at lower Ta. The metabolic response to Ta was not sufficient to maintain body temperature (Tb). In hypoxia, at all Ta, oxygen consumption (VO2) was consistently less than in normoxia and was linearly related to Ta (Q10 approximately 1.4). The rat's specific heat was 4 J.g-1.degrees C-1, and the time constant of passive heat exchange was 2.2 +/- 0.5 min; from these values it was calculated that the normoxic VO2 of the 2-day-old rat could be per se sufficient to maintain Tb of 35-36 degrees C at Ta of 33 degrees C, while at lower Ta the metabolic response could not be adequate to maintain Tb. In hypoxia, Tb was directly dependent on Ta.(ABSTRACT TRUNCATED AT 250 WORDS)

Fat levels in a subarctic population of Peromyscus maniculatus

1980 ◽  
Vol 58 (7) ◽  
pp. 1341-1346 ◽  
Author(s):  
Les W. Gyug ◽  
John S. Millar
Keyword(s):  
Peromyscus Maniculatus ◽  
Dry Weight ◽  
Caloric Content ◽  
Adult Males ◽  
Wild Mice ◽  
Ambient Temperatures ◽  
Energy Expenditures ◽  
Fat Reserves ◽  
Energy Demands ◽  
Adult Females

Fat content (FAT), lean dry weight (LDW), and caloric content (KCAL) were examined in a natural subarctic population of Peromyscus maniculatus. FAT was not significantly correlated with size (LDW) of the animal. FAT of adult males was negatively correlated with minimum ambient temperatures and was not correlated with reproductive condition. LDW of adult males did not vary in relation to season. FAT of prebreeding adult females was high and decreased in response to breeding, but LDW increased in response to breeding so that KCAL remained constant. KCAL was low in adult females only after the breeding season. Mice dying in live traps had significantly lower FAT than did any other group of adults indicating that wild mice do not normally deplete their fat reserves. KCAL of postweaning young increased with age due to an increase in LDW but not in FAT. We suggest that fat levels are intrinsically controlled in wild Peromyscus according to the probability of having to make extraordinary energy expenditures and are not simply subject to extrinsic controls through the balance of food availability and energy demands.

Studies of the environmental physiology of tropical merinos

1978 ◽  
Vol 29 (1) ◽  
pp. 161 ◽  
Author(s):  
PS Hopkins ◽  
GI Knights ◽  
AS Le Feuvre
Keyword(s):  
Low Temperature ◽  
Rectal Temperature ◽  
Water Loss ◽  
Heat Dissipation ◽  
Evaporative Water Loss ◽  
Compensatory Mechanisms ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Diurnal Patterns ◽  
Made In

Rectal temperature measurements of tropical Merino sheep taken in the sun during summer indicated that there were high and low temperature groups. Animals of low temperature status (e.g. 39.4°C) also exhibited a low respiration rate (e.g. 110/min) in comparison with their less adapted counterparts (40.0° and 190/min). These differences were greatest when ambient temperatures were high. The repeatability of temperature status was 0.46 (P < 0.01). Animals of folds (+) phenotype had significantly higher rectal temperatures than folds (–) animals (P < 0.05). Shearing caused a marked but transient increase in rectal temperature. Compensatory mechanisms apparently involved an increase in cutaneous heat dissipation and/or a decrease in exogenous heat load. Evaporative water loss (80–115 ml/kg/day) greatly exceeded the non-evaporative water loss (40–65 ml/kg/day) of sheep in metabolism cages. Respiratory water loss could account for only 8–10% of the total daily evaporative water loss. Non-respiratory evaporative water loss (as measured by difference) was c. 75–100 ml/kg/day. There were no striking differences between high and low temperature status sheep in this regard. Measurements of respiratory (2 ml/kg/hr) and non-respiratory (5.5 ml/kg/hr) evaporative water loss made in hygrometric tents suggested that the greater non-respiratory water loss was partly due to a higher rate of loss and partly to a longer period of loss per day. This suggestion was supported by the diurnal patterns of rectal temperatures and respiration rates reported here, though no firm conclusions could be made as to the thermotaxic effect of non-respiratory water loss and thermoregulation of tropical Merinos with varying amounts of wool cover.

Increased heat loss affects hibernation in golden-mantled ground squirrels

2004 ◽  
Vol 287 (1) ◽  
pp. R167-R173 ◽  
Author(s):  
Alexander S. Kauffman ◽  
Matthew J. Paul ◽  
Irving Zucker
Keyword(s):  
Food Intake ◽  
Heat Loss ◽  
Body Mass ◽  
Complete Removal ◽  
Ground Squirrels ◽  
Control Procedure ◽  
Ambient Temperatures ◽  
Spermophilus Lateralis ◽  
Maintain Body Temperature ◽  
Body Heat

During hibernation at ambient temperatures (Ta) above 0°C, rodents typically maintain body temperature (Tb) ∼1°C above Ta, reduce metabolic rate, and suspend or substantially reduce many physiological functions. We tested the extent to which the presence of an insulative pelage affects hibernation. Tb was recorded telemetrically in golden-mantled ground squirrels ( Spermophilus lateralis) housed at a Ta of 5°C; food intake and body mass were measured at regular intervals throughout the hibernation season and after the terminal arousal. Animals were subjected to complete removal of the dorsal fur or a control procedure after they had been in hibernation for 3–4 wk. Shaved squirrels continued to hibernate with little or no change in minimum Tb, bout duration, duration of periodic normothermic bouts, and food intake during normothermia. Rates of rewarming from torpor were, however, significantly slower in shaved squirrels, and rates of body mass loss were significantly higher, indicating increased depletion of white adipose energy stores. An insulative pelage evidently conserves energy over the course of the hibernation season by decreasing body heat loss and reducing energy expenditure during periodic arousals from torpor and subsequent intervals of normothermia. This prolongs the hibernation season by several weeks, thereby eliminating the debilitating consequences associated with premature emergence from hibernation.

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