Polar bear locomotion: body temperature and energetic cost

1982 ◽  
Vol 60 (1) ◽  
pp. 40-44 ◽  
Author(s):  
R. J. Hurst ◽  
M. L. Leonard ◽  
P. D. Watts ◽  
P. Beckerton ◽  
N. A. Øritsland

The metabolic response of a 190-kg polar bear was tested at four different walking speeds within a respiration chamber mounted on a treadmill. Regressions of deep body temperature and oxygen consumption as a function of walking speed were determined. Equilibrium deep body temperature increased exponentially with speed of locomotion and indicated a relative inability to dissipate metabolic heat at high walking speeds. Metabolic rate, as measured by weight-specific oxygen consumption, was also best fit by a curvilinear equation and was twice that predicted by a general equation for quadruped locomotion. The apparent inefficiency of locomotion in polar bears suggests a compromise between thermoregulation, hunting strategies, and economy of transport.

1992 ◽  
Vol 163 (1) ◽  
pp. 139-151 ◽  
Author(s):  
R. M. BEVAN ◽  
P. J. BUTLER

Six tufted ducks were trained to dive for food at summer temperatures (air, 26°C, water, 23°C) and at winter temperatures (air, 5.8°C, water 7.4°C). The mean resting oxygen consumption (Voo2) a t winter temperatures (rwin) was 90% higher than that at summer temperatures (Tsum), but deep body temperatures (Tb) were not significantly different. Diving behaviour and mean oxygen consumption for dives of mean duration were similar at Twin and at Tsum, although the mean oxygen consumption for surface intervals of mean duration was 50% greater at Twin and Tb was significantly lower (1°C) at the end of a series of dives in winter than it was in summer. There appears to be an energy saving of 67 J per dive during winter conditions and this may, at least partially, be the result of the metabolic heat produced by the active muscles being used to maintain body temperature. While at rest under winter conditions, this would be achieved by shivering thermogenesis. Thus, the energetic costs of foraging in tufted ducks in winter are not as great as might be expected from the almost doubling of metabolic rate in resting birds.


2002 ◽  
Vol 16 (4) ◽  
pp. 354-357 ◽  
Author(s):  
Michiaki Yamakage ◽  
Sohshi Iwasaki ◽  
Akiyoshi Namiki

1992 ◽  
Vol 26 (3) ◽  
pp. 191-198 ◽  
Author(s):  
Kazushi Daimon ◽  
Naoto Yamada ◽  
Tetsushi Tsujimoto ◽  
Saburo Takahashi

1987 ◽  
Vol 39 (3) ◽  
pp. 367-370 ◽  
Author(s):  
Mark S. Blumberg ◽  
Julie A. Mennella ◽  
Howard Moltz

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5600 ◽  
Author(s):  
Rebecca Naomi Cliffe ◽  
David Michael Scantlebury ◽  
Sarah Jane Kennedy ◽  
Judy Avey-Arroyo ◽  
Daniel Mindich ◽  
...  

Poikilotherms and homeotherms have different, well-defined metabolic responses to ambient temperature (Ta), but both groups have high power costs at high temperatures. Sloths (Bradypus) are critically limited by rates of energy acquisition and it has previously been suggested that their unusual departure from homeothermy mitigates the associated costs. No studies, however, have examined how sloth body temperature and metabolic rate vary with Ta. Here we measured the oxygen consumption (VO2) of eight brown-throated sloths (B. variegatus) at variable Ta’s and found that VO2 indeed varied in an unusual manner with what appeared to be a reversal of the standard homeotherm pattern. Sloth VO2 increased with Ta, peaking in a metabolic plateau (nominal ‘thermally-active zone’ (TAZ)) before decreasing again at higher Ta values. We suggest that this pattern enables sloths to minimise energy expenditure over a wide range of conditions, which is likely to be crucial for survival in an animal that operates under severe energetic constraints. To our knowledge, this is the first evidence of a mammal provisionally invoking metabolic depression in response to increasing Ta’s, without entering into a state of torpor, aestivation or hibernation.


1997 ◽  
Vol 200 (12) ◽  
pp. 1757-1763 ◽  
Author(s):  
P Hawkins ◽  
P Butler ◽  
A Woakes ◽  
G Gabrielsen

The rate of oxygen consumption (O2), respiratory quotient (RQ) and deep body temperature (TB) were recorded during a single, voluntary ingestion of Arctic cod Boreogadus saida (mean mass 18.9+/-1.1 g, s.e.m., N=13) by five postabsorptive Brunnich's guillemots (thick-billed murre, Uria lomvia). The birds were resting in air within their thermoneutral zone, and the fish were refrigerated to 0-2 degreesC. The rate of oxygen consumption increased by a factor of 1.4 during the first few minutes after ingestion, but there was no significant change in TB. Mean rate of oxygen consumption returned to preingestive levels 85 min after the birds ate the fish. The telemetered temperature of one fish reached TB within 20 min. This suggests that the persistent elevation in O2 over the next hour corresponded to the obligatory component of the heat increment of feeding (HIF) and was not related to heating the fish. Abdominal temperature increases after diving bouts in free-ranging common guillemots (common murre, Uria aalge) are possibly achieved through the HIF, since meals are processed at sea. Of the increase in O2 measured in the laboratory, it is calculated that 30 % is required to heat the fish, while 70 % is due to the HIF. In free-ranging birds, the excess heat provided by the HIF could contribute 6 % of the daily energy expenditure. This suggests that the HIF augments heat production in Uria spp. and thus reduces the energetic cost of thermoregulation.


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