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Solar heating may explain extreme diel flight altitude changes in migrating birds

Sjöberg, Sissel LU orcid ; Andersson, Arne LU orcid ; Bäckman, Johan LU orcid ; Hansson, Bengt LU orcid ; Malmiga, Gintaras LU ; Tarka, Maja LU ; Hasselquist, Dennis LU ; Lindström, Åke LU orcid and Alerstam, Thomas LU (2023) In Current Biology 33(19). p.2-4237
Abstract

Great reed warblers, Acrocephalus arundinaceus,1 and great snipes, Gallinago media,2 exhibit a diel cycle in flight altitudes—flying much higher during the day than the night—when performing migratory flights covering both night and day. One hypothesis proposed to explain this behavior is that the birds face additional heating by solar radiation during daytime and hence must climb to very high, and thus also very cold, altitudes to avoid overheating during daytime flights.1,2 Yet, solar heat gain in birds has been shown to drastically decrease with wind speed,3,4 and the quantitative heating effect by solar radiation on a bird flying with an airspeed of 10 m/s or more is unknown. We analyzed... (More)

Great reed warblers, Acrocephalus arundinaceus,1 and great snipes, Gallinago media,2 exhibit a diel cycle in flight altitudes—flying much higher during the day than the night—when performing migratory flights covering both night and day. One hypothesis proposed to explain this behavior is that the birds face additional heating by solar radiation during daytime and hence must climb to very high, and thus also very cold, altitudes to avoid overheating during daytime flights.1,2 Yet, solar heat gain in birds has been shown to drastically decrease with wind speed,3,4 and the quantitative heating effect by solar radiation on a bird flying with an airspeed of 10 m/s or more is unknown. We analyzed temperature data from multisensor data loggers (MDLs)5,6 placed without direct exposure to solar radiation on great reed warblers (the logger covered by feathers on the back) and great snipes (the logger on the leg, covered from the sun by the tail). We found that logger temperatures were significantly higher (5.9°C–8.8°C in great reed warblers and 4.8°C–5.4°C in great snipes) during the day than during the night in birds flying at the same altitudes (and thus also the same expected ambient air temperatures). These results strongly indicate that the heat balance of the flying birds is indeed affected by solar radiation, which is in accordance with the hypothesis that solar radiation is a key factor causing the remarkable diel cycles in flight altitude observed in these two long-distance migrant bird species.1,2

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
diel cycle in altitude, flight altitude, flight behavior, migration, multisensor data loggers, shorebird, solar heating, solar radiation, songbird, temperature regulation
in
Current Biology
volume
33
issue
19
pages
2 - 4237
publisher
Elsevier
external identifiers
  • pmid:37689066
  • scopus:85173584180
ISSN
0960-9822
DOI
10.1016/j.cub.2023.08.035
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2023 The Authors
id
cab68783-eff9-4f6f-a5cc-a1a2eed05c9b
date added to LUP
2023-10-31 13:36:00
date last changed
2025-01-26 09:45:39
@article{cab68783-eff9-4f6f-a5cc-a1a2eed05c9b,
  abstract     = {{<p>Great reed warblers, Acrocephalus arundinaceus,<sup>1</sup> and great snipes, Gallinago media,<sup>2</sup> exhibit a diel cycle in flight altitudes—flying much higher during the day than the night—when performing migratory flights covering both night and day. One hypothesis proposed to explain this behavior is that the birds face additional heating by solar radiation during daytime and hence must climb to very high, and thus also very cold, altitudes to avoid overheating during daytime flights.<sup>1,2</sup> Yet, solar heat gain in birds has been shown to drastically decrease with wind speed,<sup>3,4</sup> and the quantitative heating effect by solar radiation on a bird flying with an airspeed of 10 m/s or more is unknown. We analyzed temperature data from multisensor data loggers (MDLs)<sup>5,6</sup> placed without direct exposure to solar radiation on great reed warblers (the logger covered by feathers on the back) and great snipes (the logger on the leg, covered from the sun by the tail). We found that logger temperatures were significantly higher (5.9°C–8.8°C in great reed warblers and 4.8°C–5.4°C in great snipes) during the day than during the night in birds flying at the same altitudes (and thus also the same expected ambient air temperatures). These results strongly indicate that the heat balance of the flying birds is indeed affected by solar radiation, which is in accordance with the hypothesis that solar radiation is a key factor causing the remarkable diel cycles in flight altitude observed in these two long-distance migrant bird species.<sup>1,2</sup></p>}},
  author       = {{Sjöberg, Sissel and Andersson, Arne and Bäckman, Johan and Hansson, Bengt and Malmiga, Gintaras and Tarka, Maja and Hasselquist, Dennis and Lindström, Åke and Alerstam, Thomas}},
  issn         = {{0960-9822}},
  keywords     = {{diel cycle in altitude; flight altitude; flight behavior; migration; multisensor data loggers; shorebird; solar heating; solar radiation; songbird; temperature regulation}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{19}},
  pages        = {{2--4237}},
  publisher    = {{Elsevier}},
  series       = {{Current Biology}},
  title        = {{Solar heating may explain extreme diel flight altitude changes in migrating birds}},
  url          = {{http://dx.doi.org/10.1016/j.cub.2023.08.035}},
  doi          = {{10.1016/j.cub.2023.08.035}},
  volume       = {{33}},
  year         = {{2023}},
}