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Body surface temperature responses to food restriction in wild and captive great tits

Author:
  • Lucy Winder
  • Stewart White
  • Andreas Nord
  • Barbara Helm
  • Dominic J. McCafferty
Publishing year: 2020
Language: English
Pages:
Publication/Series: Journal of Experimental Biology
Volume: 223
Issue: 8
Document type: Journal article
Publisher: The Company of Biologists Ltd

Abstract english

During winter at temperate and high latitudes, the low ambient temperatures, limited food supplies and short foraging periods mean small passerines show behavioural, morphological and physiological adaptations to reduce the risk of facing energy shortages. Peripheral tissues vasoconstrict in low ambient temperatures to reduce heat loss and cold injury. Peripheral vasoconstriction has been observed with food restriction in captivity but has yet to be explored in free-ranging animals. We experimentally food restricted both wild and captive great tits (Parus major) during winter months and measured surface temperatures of the bill and eye region using thermal imaging, to investigate whether birds show rapid local heterothermic responses, which may reduce their thermoregulatory costs when facing a perceived imminent food shortage. Our results of a continuously filmed wild population showed that bill temperature was immediately reduced in response to food restriction compared with when food was available ad libitum, an apparent autonomic response. Such immediacy implies a ‘pre-emptive’ response before the bird experiences any shortfalls in energy reserves. We also demonstrate temporal variation in vasoconstriction of the bill, with bill temperature gradually rising throughout the food restriction after the initial drop. Eye-region temperature in the wild birds remained at similar levels throughout food restriction compared with unrestricted birds, possibly reflecting the need to maintain steady circulation to the central nervous and visual systems. Our findings provide evidence that birds selectively allow the bill to cool when a predictable food supply is suddenly disrupted, probably as a means of minimising depletion of body reserves for a perceived future shortage in energy.

Keywords

  • Ecology
  • Zoology
  • thermoregulation
  • winter
  • energy
  • infrared thermography
  • bird
  • bird
  • thermoregulation
  • season
  • winter
  • infrared thermography

Other

Published
  • ISSN: 1477-9145
Andreas Nord at NHM London
E-mail: andreas [dot] nord [at] biol [dot] lu [dot] se

Researcher

Evolutionary ecology

+46 70 495 32 62

C255

Ekologihuset, Sölvegatan 37, Lund

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