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Seasonal variation in the thermal responses to changing environmental temperature in the world's northernmost land bird

Nord, Andreas LU and Folkow, Lars P. (2018) In Journal of Experimental Biology 221(1).
Abstract

Arctic homeotherms counter challenges at high latitudes using a combination of seasonal adjustments in pelage/plumage, fat deposition and intricate thermoregulatory adaptations. However, there are still gaps in our understanding of their thermal responses to cold, particularly in Arctic birds. Here, we have studied the potential use of local heterothermy (i.e. tissue cooling that can contribute to significantly lower heat loss rate) in Svalbard ptarmigan (Lagopus muta hyperborea) °C the world's northernmost land bird. We exposed birds kept under simulated Svalbard photoperiod to low ambient temperatures (Ta; between 0 and -30°C) during three seasons (early winter, late winter, summer), whilst recording resting metabolic rate... (More)

Arctic homeotherms counter challenges at high latitudes using a combination of seasonal adjustments in pelage/plumage, fat deposition and intricate thermoregulatory adaptations. However, there are still gaps in our understanding of their thermal responses to cold, particularly in Arctic birds. Here, we have studied the potential use of local heterothermy (i.e. tissue cooling that can contribute to significantly lower heat loss rate) in Svalbard ptarmigan (Lagopus muta hyperborea) °C the world's northernmost land bird. We exposed birds kept under simulated Svalbard photoperiod to low ambient temperatures (Ta; between 0 and -30°C) during three seasons (early winter, late winter, summer), whilst recording resting metabolic rate (RMR), core temperature (Tc) and several cutaneous temperatures. Leg skin temperature varied the most, but still only by up to 15°C, whereas body trunk skin temperature changed 1°C when Ta decreased from 0 to -30°C. At the same time, Tc increased by 0.9°C, concomitant with increased RMR. This was probably driven by the triggering of cerebral thermosensors in response to cooling of the poorly insulated head, the skin of which was 5.4°C colder at -30°C than at 0°C. Thermal conductance in winter was higher in yearlings, probably because they were time/resource constrained from acquiring a high-quality plumage and sufficient fat reserves as a result of concomitant body growth. In conclusion, Svalbard ptarmigan do not employ extensive local heterothermy for cold protection but instead rely on efficient thermogenesis combined with excellent body insulation. Hence, cold defence in the world's northernmost land bird is not mechanistically much different from that of its lower latitude relatives.

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organization
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Contribution to journal
publication status
published
subject
keywords
Arctic, Heat loss rate, Heterothermy, Peripheral temperature, Seasonal acclimatization, Thermoregulation
in
Journal of Experimental Biology
volume
221
issue
1
publisher
The Company of Biologists Ltd
external identifiers
  • scopus:85040528625
ISSN
0022-0949
DOI
language
English
LU publication?
yes
id
40531fa4-4f95-488f-a025-8aa251515f2c
date added to LUP
2018-01-30 15:02:57
date last changed
2018-05-29 11:14:30
@article{40531fa4-4f95-488f-a025-8aa251515f2c,
  abstract     = {<p>Arctic homeotherms counter challenges at high latitudes using a combination of seasonal adjustments in pelage/plumage, fat deposition and intricate thermoregulatory adaptations. However, there are still gaps in our understanding of their thermal responses to cold, particularly in Arctic birds. Here, we have studied the potential use of local heterothermy (i.e. tissue cooling that can contribute to significantly lower heat loss rate) in Svalbard ptarmigan (Lagopus muta hyperborea) °C the world's northernmost land bird. We exposed birds kept under simulated Svalbard photoperiod to low ambient temperatures (T<sub>a</sub>; between 0 and -30°C) during three seasons (early winter, late winter, summer), whilst recording resting metabolic rate (RMR), core temperature (Tc) and several cutaneous temperatures. Leg skin temperature varied the most, but still only by up to 15°C, whereas body trunk skin temperature changed 1°C when Ta decreased from 0 to -30°C. At the same time, T<sub>c</sub> increased by 0.9°C, concomitant with increased RMR. This was probably driven by the triggering of cerebral thermosensors in response to cooling of the poorly insulated head, the skin of which was 5.4°C colder at -30°C than at 0°C. Thermal conductance in winter was higher in yearlings, probably because they were time/resource constrained from acquiring a high-quality plumage and sufficient fat reserves as a result of concomitant body growth. In conclusion, Svalbard ptarmigan do not employ extensive local heterothermy for cold protection but instead rely on efficient thermogenesis combined with excellent body insulation. Hence, cold defence in the world's northernmost land bird is not mechanistically much different from that of its lower latitude relatives.</p>},
  author       = {Nord, Andreas and Folkow, Lars P.},
  issn         = {0022-0949},
  keyword      = {Arctic,Heat loss rate,Heterothermy,Peripheral temperature,Seasonal acclimatization,Thermoregulation},
  language     = {eng},
  month        = {01},
  number       = {1},
  publisher    = {The Company of Biologists Ltd},
  series       = {Journal of Experimental Biology},
  title        = {Seasonal variation in the thermal responses to changing environmental temperature in the world's northernmost land bird},
  url          = {http://dx.doi.org/},
  volume       = {221},
  year         = {2018},
}