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Dissimilar use of an external heat source for thermoregulation by shrews from different geographic regions. J Therm Biol 2022; 104:103193. [DOI: 10.1016/j.jtherbio.2022.103193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 01/19/2022] [Accepted: 01/21/2022] [Indexed: 11/18/2022]
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Dausmann KH, Levesque DL, Wein J, Nowack J. Ambient Temperature Cycles Affect Daily Torpor and Hibernation Patterns in Malagasy Tenrecs. Front Physiol 2020; 11:522. [PMID: 32547412 PMCID: PMC7270353 DOI: 10.3389/fphys.2020.00522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/28/2020] [Indexed: 11/30/2022] Open
Abstract
Hibernation and daily torpor (heterothermy) allow endotherms to cope with demanding environmental conditions. The depth and duration of torpor bouts vary considerably between tropical and temperate climates, and tropical hibernators manage to cope with a wider spectrum of ambient temperature (Ta) regimes during heterothermy. As cycles in Ta can have profound effects on activity and torpor patterns as well as energy expenditure, we examined how these characteristics are affected by daily fluctuating versus constant Ta in a tropical hibernator, the lesser hedgehog tenrec (Echinops telfairi). Throughout the study, regardless of season, the tenrecs became torpid every day. In summer, E. telfairi used daily fluctuations in Ta to passively rewarm from daily torpor, which led to synchrony in the activity phases and torpor bouts between individuals and generally decreased energy expenditure. In contrast, animals housed at constant Ta showed considerable variation in timing and they had to invest more energy through endogenous heat production. During the hibernation season (winter) E. telfairi hibernated for several months in constant, as well as in fluctuating Ta and, as in summer, under fluctuating Ta arousals were much more uniform and showed less variation in timing compared to constant temperature regimes. The timing of torpor is not only important for its effective use, but synchronization of activity patterns could also be essential for social interactions, and successful foraging bouts. Our results highlight that Ta cycles can be an effective zeitgeber for activity and thermoregulatory rhythms throughout the year and that consideration should be given to the choice of temperature regime when studying heterothermy under laboratory conditions.
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Affiliation(s)
- Kathrin H Dausmann
- Functional Ecology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Danielle L Levesque
- School of Biology and Ecology, University of Maine, Orono, ME, United States
| | - Jens Wein
- Functional Ecology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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3
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The avian "hibernation" enigma: thermoregulatory patterns and roost choice of the common poorwill. Oecologia 2018; 189:47-53. [PMID: 30460539 DOI: 10.1007/s00442-018-4306-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 11/13/2018] [Indexed: 02/06/2023]
Abstract
Compared to mammals, there are relatively few studies examining heterothermy in birds. In 13 bird families known to contain heterothermic species, the common poorwill (Phalaenoptilus nuttallii) is the only species that ostensibly hibernates. We used temperature-sensitive radio-transmitters to collect roost and skin temperature (Tskin) data, and winter roost preferences for free-ranging poorwills in southern Arizona. Further, to determine the effect of passive rewarming on torpor bout duration and active rewarming (i.e., the use of metabolic heat to increase Tskin), we experimentally shaded seven birds during winter to prevent them from passively rewarming via solar radiation. Poorwills selected winter roosts that were open to the south or southwest, facilitating passive solar warming in the late afternoon. Shaded birds actively rewarmed following at least 3 days of continuous torpor. Average torpor bout duration by shaded birds was 122 h and ranged from 91 to 164 h. Active rewarming by shaded birds occurred on significantly warmer days than those when poorwills remained torpid. One shaded bird remained inactive for 45 days, during which it spontaneously rewarmed actively on eight occasions. Our findings show that during winter poorwills exhibit physiological patterns and active rewarming similar to hibernating mammals.
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Lopes KGD, Bicca-Marques JC. Ambient temperature and humidity modulate the behavioural thermoregulation of a small arboreal mammal (Callicebus bernhardi). J Therm Biol 2017; 69:104-109. [PMID: 29037369 DOI: 10.1016/j.jtherbio.2017.06.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/28/2017] [Accepted: 06/28/2017] [Indexed: 11/27/2022]
Abstract
Maintaining a constant body temperature is critical to the proper functioning of metabolic reactions. Behavioural thermoregulation strategies may minimize the cost of energetic balance when an animal is outside its thermoneutral zone. We investigated whether ambient temperature and relative air humidity influence the use of behavioural strategies by a group of Prince Bernhard's titi monkeys (Callicebus bernhardi) living in a forest fragment. We monitored a social group composed of four individuals (an adult couple and two juveniles) for 1010h from March to September 2015. We used the instantaneous scan sampling method to record the body posture, the microhabitat, and the occurrence of huddling with group mate(s) when animals were resting. We recorded ambient temperature and relative humidity in the shade every 10min with a data logger hanging at a height of approximately 5m. Daytime temperature ranged from 18.5°C to 38.5°C and relative humidity ranged from 21% to 97%. Titi monkeys avoided sunny places at higher temperatures, especially above 31°C. Minimum night temperature did not influence the choice of resting microhabitats during the first hour after sunrise. Sitting was the major resting posture during the day (62%). Titi monkeys increased the use of heat-dissipating postures at ambient temperatures >27°C. In addition, an increase in relative humidity increased the use of these postures at 26°C, 27°C, 29°C and 33°C, but caused a decrease at 24°C. On the other hand, the ambient temperature did not influence the occurrence of huddling. We conclude that microhabitat choice and postural behaviour are important for titi monkeys to prevent overheating and suggest that these behavioural adjustments might also be critical for other tropical arboreal mammals.
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Affiliation(s)
- Karine G D Lopes
- Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Brazil
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Wacker CB, McAllan BM, Körtner G, Geiser F. The role of basking in the development of endothermy and torpor in a marsupial. J Comp Physiol B 2017; 187:1029-1038. [PMID: 28283794 DOI: 10.1007/s00360-017-1060-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/02/2017] [Accepted: 01/18/2017] [Indexed: 10/20/2022]
Abstract
Marsupials have a slow rate of development and this allows a detailed examination of thermoregulatory developmental changes and stages. We quantified the cooling rates of marsupial dunnarts (Sminthopsis crassicaudata) at 40-56 days (d) old, and torpor and basking behaviour in animals given the option to bask in four age groups from 60 to 150 d. The development of thermoregulation was a continuum, but was characterised by three major thermoregulatory stages: (1) at 40 d, animals were unable to maintain a constant high body temperature during short-term cold exposure; (2) at 60 d, animals could maintain a high T b for the first part of the night at an ambient temperature of 15.0 ± 0.7 °C; later in the night, they entered an apparent torpor bout but could only rewarm passively when basking under a heat lamp; (3) from ~90 d, they expressed prolonged torpor bouts and were able to rewarm endogenously. Young newly weaned 60 d animals were able to avoid hypothermia by basking. In this case, basking was not an optional behavioural method of reducing the cost of rewarming from torpor, but was essential for thermoregulation independent of the nest temperature. Results from our study suggest that basking is a crucial behavioural trait that permits young marsupials and perhaps other juvenile altricial mammals to overcome the developmental stage between poikilothermy early in development and full endothermy later in life.
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Affiliation(s)
- Chris B Wacker
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia.
| | - Bronwyn M McAllan
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia.,Physiology, School of Medical Sciences, Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia
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Matthews JK, Stawski C, Körtner G, Parker CA, Geiser F. Torpor and basking after a severe wildfire: mammalian survival strategies in a scorched landscape. J Comp Physiol B 2016; 187:385-393. [DOI: 10.1007/s00360-016-1039-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 09/14/2016] [Accepted: 09/30/2016] [Indexed: 11/24/2022]
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Levesque DL, Nowack J, Stawski C. Modelling mammalian energetics: the heterothermy problem. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s40665-016-0022-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Wacker CB, McAllan BM, Körtner G, Geiser F. The functional requirements of mammalian hair: a compromise between crypsis and thermoregulation? Naturwissenschaften 2016; 103:53. [PMID: 27287044 DOI: 10.1007/s00114-016-1376-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 05/20/2016] [Accepted: 05/23/2016] [Indexed: 11/28/2022]
Abstract
Mammalian fur often shows agouti banding with a proximal dark band near the skin and a lighter distal band. We examined the function of both bands in relation to camouflage, thermal properties of pelts, and thermal energetics of dunnarts (Sminthopsis crassicaudata), which are known to use torpor and basking. Although the distal band of dunnart fur darkened with increasing latitude, which is important for camouflage, it did not affect the thermal properties and the length of the dark band and total hair length were not correlated. In contrast, the length of the proximal dark band of preserved pelts exposed to sunlight was positively correlated (r (2) = 0.59) with the temperature underneath the pelt (T pelt). All dunnarts offered radiant heat basked by exposing the dark band of the hair during both rest and torpor. Basking dunnarts with longer dark bands had lower resting metabolism (r (2) = 0.69), warmed faster from torpor (r (2) = 0.77), required less energy to do so (r (2) = 0.32), and reached a higher subcutaneous temperature (T sub) at the end of rewarming (r (2) = 0.75). We provide the first experimental evidence on the possible dual function of the color banding of mammalian fur. The distal colored band appears to be important for camouflage, whereas the length of the dark proximal hair band facilitates heat gain for energy conservation and allows animals to rewarm quickly and economically from torpor.
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Affiliation(s)
- Chris B Wacker
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales, 2351, Australia.
| | - Bronwyn M McAllan
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales, 2351, Australia.,Physiology, School of Medical Sciences, Bosch Institute, The University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales, 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales, 2351, Australia
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Geiser F, Gasch K, Bieber C, Stalder GL, Gerritsmann H, Ruf T. Basking hamsters reduce resting metabolism, body temperature and energy costs during rewarming from torpor. ACTA ACUST UNITED AC 2016; 219:2166-72. [PMID: 27207637 DOI: 10.1242/jeb.137828] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/02/2016] [Indexed: 01/22/2023]
Abstract
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 (Ta) of ∼15 and 0°C. Interestingly, body temperature (Tb) also was significantly reduced from 34.7±0.6°C (Ta 15°C, not basking) to 30.4±2.0°C (Ta 0°C, basking), which resulted in an extremely low (<50% of predicted) apparent thermal conductance. Induced torpor (food withheld) during respirometry at Ta 15°C occurred on 83.3±36.0% of days and the minimum torpor MR was 36% of basal MR at an average Tb of 22.0±2.6°C; movement to the basking lamp occurred at Tb<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 Tb during torpor. Our data show that basking substantially modifies thermal energetics in hamsters, with a drop of resting Tb 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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Affiliation(s)
- Fritz Geiser
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Kristina Gasch
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Claudia Bieber
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Gabrielle L Stalder
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Hanno Gerritsmann
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Thomas Ruf
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
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Stawski C, Körtner G, Nowack J, Geiser F. The importance of mammalian torpor for survival in a post-fire landscape. Biol Lett 2016; 11:20150134. [PMID: 26063748 DOI: 10.1098/rsbl.2015.0134] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Wildfires have increased in frequency and intensity worldwide with climate change as a main driving factor. While a number of studies have focused on population changes in regard to fires, there are essentially no quantitative data on behavioural and physiological adjustments that are vital for the persistence of individuals during and after fires. Here we show that brown antechinus, a small insectivorous marsupial mammal, (i) endured a prescribed fire in situ, (ii) remained in their scorched home range despite unburned areas nearby, and (iii) substantially increased post-fire torpor use and thus reduced foraging requirements and exposure to predators. Hence, torpor is a physiological adaptation that, although not quantified in this context previously, appears to play a key role in post-fire survival for this and other heterothermic species.
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Affiliation(s)
- Clare Stawski
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
| | - Julia Nowack
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
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To bask or not to bask: Behavioural thermoregulation in two species of dasyurid, Phascogale calura and Antechinomys laniger. J Therm Biol 2015; 53:66-71. [DOI: 10.1016/j.jtherbio.2015.08.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 08/18/2015] [Accepted: 08/21/2015] [Indexed: 11/22/2022]
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