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Predictability of food supply modulates nocturnal hypothermia in a small passerine : Food supply and nocturnal hypothermia

Nilsson, Johan F. LU ; Nilsson, Jan Åke LU ; Broggi, Juli LU and Watson, Hannah LU (2020) In Biology letters 16(6).
Abstract

The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great tits Parus major. A 'predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed... (More)

The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great tits Parus major. A 'predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally 'unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
birds, body temperature, energetics, food supply, hypothermia, thermoregulation
in
Biology letters
volume
16
issue
6
article number
20200133
publisher
Royal Society
external identifiers
  • pmid:32486941
  • scopus:85085854641
ISSN
1744-9561
DOI
10.1098/rsbl.2020.0133rsbl20200133
language
English
LU publication?
yes
id
90fd2c0e-edcc-4072-9362-bd3c717fa953
date added to LUP
2021-01-12 09:51:41
date last changed
2021-04-06 04:12:33
@article{90fd2c0e-edcc-4072-9362-bd3c717fa953,
  abstract     = {<p>The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great tits Parus major. A 'predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally 'unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night.</p>},
  author       = {Nilsson, Johan F. and Nilsson, Jan Åke and Broggi, Juli and Watson, Hannah},
  issn         = {1744-9561},
  language     = {eng},
  number       = {6},
  publisher    = {Royal Society},
  series       = {Biology letters},
  title        = {Predictability of food supply modulates nocturnal hypothermia in a small passerine : Food supply and nocturnal hypothermia},
  url          = {http://dx.doi.org/10.1098/rsbl.2020.0133rsbl20200133},
  doi          = {10.1098/rsbl.2020.0133rsbl20200133},
  volume       = {16},
  year         = {2020},
}