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Adaptive temperature regulation in the little bird in winter : predictions from a stochastic dynamic programming model

Brodin, Anders LU ; Nilsson, Jan Åke LU and Nord, Andreas LU (2017) In Oecologia p.1-12
Abstract

Several species of small birds are resident in boreal forests where environmental temperatures can be −20 to −30 °C, or even lower, in winter. As winter days are short, and food is scarce, winter survival is a challenge for small endothermic animals. A bird of this size will have to gain almost 10% of its lean body mass in fat every day to sustain overnight metabolism. Birds such as parids (titmice and chickadees) can use facultative hypothermia, a process in which body temperature is actively down-regulated to a specific level, to reduce heat loss and thus save energy. During cold winter nights, these birds may decrease body temperature from the normal from 42 ° down to 35 °C, or even lower in some species. However, birds are unable to... (More)

Several species of small birds are resident in boreal forests where environmental temperatures can be −20 to −30 °C, or even lower, in winter. As winter days are short, and food is scarce, winter survival is a challenge for small endothermic animals. A bird of this size will have to gain almost 10% of its lean body mass in fat every day to sustain overnight metabolism. Birds such as parids (titmice and chickadees) can use facultative hypothermia, a process in which body temperature is actively down-regulated to a specific level, to reduce heat loss and thus save energy. During cold winter nights, these birds may decrease body temperature from the normal from 42 ° down to 35 °C, or even lower in some species. However, birds are unable to move in this deep hypothermic state, making it a risky strategy if predators are around. Why, then, do small northern birds enter a potentially dangerous physiological state for a relatively small reduction in energy expenditure? We used stochastic dynamic programming to investigate this. Our model suggests that the use of nocturnal hypothermia at night is paramount in these biomes, as it would increase winter survival for a small northern bird by 58% over a winter of 100 days. Our model also explains the phenomenon known as winter fattening, and its relationship to thermoregulation, in northern birds.

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author
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
Body temperature regulation, Dynamic programming, Facultative hypothermia, Heterothermy, Hypothermia, Little bird in winter, Winter fattening
in
Oecologia
pages
12 pages
publisher
Springer
external identifiers
  • scopus:85026827457
ISSN
0029-8549
DOI
10.1007/s00442-017-3923-3
language
English
LU publication?
yes
id
6b6b797e-b731-4094-8680-6e69ec578947
date added to LUP
2017-08-29 14:35:50
date last changed
2017-08-30 03:00:02
@article{6b6b797e-b731-4094-8680-6e69ec578947,
  abstract     = {<p>Several species of small birds are resident in boreal forests where environmental temperatures can be −20 to −30 °C, or even lower, in winter. As winter days are short, and food is scarce, winter survival is a challenge for small endothermic animals. A bird of this size will have to gain almost 10% of its lean body mass in fat every day to sustain overnight metabolism. Birds such as parids (titmice and chickadees) can use facultative hypothermia, a process in which body temperature is actively down-regulated to a specific level, to reduce heat loss and thus save energy. During cold winter nights, these birds may decrease body temperature from the normal from 42 ° down to 35 °C, or even lower in some species. However, birds are unable to move in this deep hypothermic state, making it a risky strategy if predators are around. Why, then, do small northern birds enter a potentially dangerous physiological state for a relatively small reduction in energy expenditure? We used stochastic dynamic programming to investigate this. Our model suggests that the use of nocturnal hypothermia at night is paramount in these biomes, as it would increase winter survival for a small northern bird by 58% over a winter of 100 days. Our model also explains the phenomenon known as winter fattening, and its relationship to thermoregulation, in northern birds.</p>},
  author       = {Brodin, Anders and Nilsson, Jan Åke and Nord, Andreas},
  issn         = {0029-8549},
  keyword      = {Body temperature regulation,Dynamic programming,Facultative hypothermia,Heterothermy,Hypothermia,Little bird in winter,Winter fattening},
  language     = {eng},
  month        = {08},
  pages        = {1--12},
  publisher    = {Springer},
  series       = {Oecologia},
  title        = {Adaptive temperature regulation in the little bird in winter : predictions from a stochastic dynamic programming model},
  url          = {http://dx.doi.org/10.1007/s00442-017-3923-3},
  year         = {2017},
}