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Deep body and surface temperature responses to hot and cold environments in the zebra finch

Szafrańska, Paulina Anna LU ; Andreasson, Fredrik LU ; Nord, Andreas LU and Nilsson, Jan Åke LU (2020) In Journal of Thermal Biology 94.
Abstract

Global warming increasingly challenges thermoregulation in endothermic animals, particularly in hot and dry environments where low water availability and high temperature increase the risk of hyperthermia. In birds, un-feathered body parts such as the head and bill work as ‘thermal windows’, because heat flux is higher compared to more insulated body regions. We studied how such structures were used in different thermal environments, and if heat flux properties change with time in a given temperature. We acclimated zebra finches (Taeniopygia guttata) to two different ambient temperatures, ‘cold’ (5 °C) and ‘hot’ (35 °C), and measured the response in core body temperature using a thermometer, and head surface temperature using thermal... (More)

Global warming increasingly challenges thermoregulation in endothermic animals, particularly in hot and dry environments where low water availability and high temperature increase the risk of hyperthermia. In birds, un-feathered body parts such as the head and bill work as ‘thermal windows’, because heat flux is higher compared to more insulated body regions. We studied how such structures were used in different thermal environments, and if heat flux properties change with time in a given temperature. We acclimated zebra finches (Taeniopygia guttata) to two different ambient temperatures, ‘cold’ (5 °C) and ‘hot’ (35 °C), and measured the response in core body temperature using a thermometer, and head surface temperature using thermal imaging. Birds in the hot treatment had 10.3 °C higher head temperature than those in the cold treatment. Thermal acclimation also resulted in heat storage in the hot group: core body temperature was 1.1 °C higher in the 35 °C group compared to the 5 °C group. Hence, the thermal gradient from core to shell was 9.03 °C smaller in the hot treatment. Dry heat transfer rate from the head was significantly lower in the hot compared to the cold treatment after four weeks of thermal acclimation. This reflects constraints on changes to peripheral circulation and maximum body temperature. Heat dissipation capacity from the head region increased with acclimation time in the hot treatment, perhaps because angiogenesis was required to reach peak heat transfer rate. We have shown that zebra finches meet high environmental temperature by heat storage, which saves water and energy, and by peripheral vasodilation in the head, which facilitates dry heat loss. These responses will not exclude the need for evaporative cooling, but will lessen the amount of energy expend on body temperature reduction in hot environments.

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author
; ; and
organization
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type
Contribution to journal
publication status
published
subject
keywords
(Max 6): heat dissipation, Hyperthermia, Thermal imaging, Thermal window, Thermoregulation, Zebra finch
in
Journal of Thermal Biology
volume
94
article number
102776
publisher
Elsevier
external identifiers
  • pmid:33292974
  • scopus:85096181529
ISSN
0306-4565
DOI
10.1016/j.jtherbio.2020.102776
language
English
LU publication?
yes
id
5cec7666-4345-48a1-ba33-8557f9f1fe80
date added to LUP
2020-11-23 14:41:36
date last changed
2021-04-06 03:53:16
@article{5cec7666-4345-48a1-ba33-8557f9f1fe80,
  abstract     = {<p>Global warming increasingly challenges thermoregulation in endothermic animals, particularly in hot and dry environments where low water availability and high temperature increase the risk of hyperthermia. In birds, un-feathered body parts such as the head and bill work as ‘thermal windows’, because heat flux is higher compared to more insulated body regions. We studied how such structures were used in different thermal environments, and if heat flux properties change with time in a given temperature. We acclimated zebra finches (Taeniopygia guttata) to two different ambient temperatures, ‘cold’ (5 °C) and ‘hot’ (35 °C), and measured the response in core body temperature using a thermometer, and head surface temperature using thermal imaging. Birds in the hot treatment had 10.3 °C higher head temperature than those in the cold treatment. Thermal acclimation also resulted in heat storage in the hot group: core body temperature was 1.1 °C higher in the 35 °C group compared to the 5 °C group. Hence, the thermal gradient from core to shell was 9.03 °C smaller in the hot treatment. Dry heat transfer rate from the head was significantly lower in the hot compared to the cold treatment after four weeks of thermal acclimation. This reflects constraints on changes to peripheral circulation and maximum body temperature. Heat dissipation capacity from the head region increased with acclimation time in the hot treatment, perhaps because angiogenesis was required to reach peak heat transfer rate. We have shown that zebra finches meet high environmental temperature by heat storage, which saves water and energy, and by peripheral vasodilation in the head, which facilitates dry heat loss. These responses will not exclude the need for evaporative cooling, but will lessen the amount of energy expend on body temperature reduction in hot environments.</p>},
  author       = {Szafrańska, Paulina Anna and Andreasson, Fredrik and Nord, Andreas and Nilsson, Jan Åke},
  issn         = {0306-4565},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Journal of Thermal Biology},
  title        = {Deep body and surface temperature responses to hot and cold environments in the zebra finch},
  url          = {http://dx.doi.org/10.1016/j.jtherbio.2020.102776},
  doi          = {10.1016/j.jtherbio.2020.102776},
  volume       = {94},
  year         = {2020},
}