Fred Ruhe
Well-known member
Alexandra McQueen, Ryan Barnaby, Matthew R. E. Symonds and Glenn J. Tattersall, 2023
Birds are better at regulating heat loss through their legs than their bills: implications for body shape evolution in response to climate
Biology Letters 19(11): 20230373
doi: https://doi.org/10.1098/rsbl.2023.0373
https://royalsocietypublishing.org/doi/10.1098/rsbl.2023.0373
Free pdf:
https://royalsocietypublishing.org/doi/epdf/10.1098/rsbl.2023.0373
Abstract:
royalsocietypublishing.org/journal/rsblResearchCite this article:McQueen A, Barnaby R,Symonds MRE, Tattersall GJ. 2023 Birds arebetter at regulating heat loss through theirlegs than their bills: implications for bodyshape evolution in response to climate.Biol.Lett.19: 20230373.https://doi.org/10.1098/rsbl.2023.0373Received: 17 August 2023Accepted: 1 November 2023Subject Category:Animal behaviourSubject Areas:behaviour, ecologyKeywords:Allen’s rule, beak, heat exchange,infrared thermography, shape-shifting,thermoregulationAuthor for correspondence:Alexandra McQueene-mail: [email protected] supplementary material is availableonline at https://doi.org/10.6084/m9.figshare.c.6927472.Birds are better at regulating heat lossthrough their legs than their bills:implications for body shape evolutionin response to climateAlexandra McQueen1, Ryan Barnaby1, Matthew R. E. Symonds1andGlenn J. Tattersall21Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood,VIC 3125, Australia2Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario,Canada L2S 3A1AM, 0000-0002-2375-963X; MRES, 0000-0002-9785-6045; GJT, 0000-0002-6591-6760Endotherms use their appendages—such as legs, tails, ears and bills—forthermoregulation by controlling blood flow to near-surface blood vessels,conserving heat when it is cold, and dissipating heat in hot conditions.Larger appendages allow greater heat dissipation, and appendage sizes varylatitudinally according to Allen’s rule. However, little is known about the rela-tive importance of different appendages for thermoregulation. We investigatephysiological control of heat loss via bird bills and legs using infrared thermo-graphy of wild birds. Our results demonstrate that birds are less able toregulate heat loss via their bills than their legs. In cold conditions, birdslower their leg surface temperature to below that of their plumage surface,retaining heat at their core. In warm conditions, birds increase their leg surfacetemperature to above that of their plumage surface, expelling heat. By contrast,bill surface temperature remains approximately 2°C warmer than the plumagesurface, indicating consistent heat loss under almost all conditions. Poorerphysiological control of heat loss via bird bills likely entails stronger selectionfor shorter bills in cold climates. This could explain why bird bills show stron-ger latitudinal size clines than bird legs, with implications for predictingshape-shifting responses to climate change.
Enhjoy,
Fred
Birds are better at regulating heat loss through their legs than their bills: implications for body shape evolution in response to climate
Biology Letters 19(11): 20230373
doi: https://doi.org/10.1098/rsbl.2023.0373
https://royalsocietypublishing.org/doi/10.1098/rsbl.2023.0373
Free pdf:
https://royalsocietypublishing.org/doi/epdf/10.1098/rsbl.2023.0373
Abstract:
royalsocietypublishing.org/journal/rsblResearchCite this article:McQueen A, Barnaby R,Symonds MRE, Tattersall GJ. 2023 Birds arebetter at regulating heat loss through theirlegs than their bills: implications for bodyshape evolution in response to climate.Biol.Lett.19: 20230373.https://doi.org/10.1098/rsbl.2023.0373Received: 17 August 2023Accepted: 1 November 2023Subject Category:Animal behaviourSubject Areas:behaviour, ecologyKeywords:Allen’s rule, beak, heat exchange,infrared thermography, shape-shifting,thermoregulationAuthor for correspondence:Alexandra McQueene-mail: [email protected] supplementary material is availableonline at https://doi.org/10.6084/m9.figshare.c.6927472.Birds are better at regulating heat lossthrough their legs than their bills:implications for body shape evolutionin response to climateAlexandra McQueen1, Ryan Barnaby1, Matthew R. E. Symonds1andGlenn J. Tattersall21Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood,VIC 3125, Australia2Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario,Canada L2S 3A1AM, 0000-0002-2375-963X; MRES, 0000-0002-9785-6045; GJT, 0000-0002-6591-6760Endotherms use their appendages—such as legs, tails, ears and bills—forthermoregulation by controlling blood flow to near-surface blood vessels,conserving heat when it is cold, and dissipating heat in hot conditions.Larger appendages allow greater heat dissipation, and appendage sizes varylatitudinally according to Allen’s rule. However, little is known about the rela-tive importance of different appendages for thermoregulation. We investigatephysiological control of heat loss via bird bills and legs using infrared thermo-graphy of wild birds. Our results demonstrate that birds are less able toregulate heat loss via their bills than their legs. In cold conditions, birdslower their leg surface temperature to below that of their plumage surface,retaining heat at their core. In warm conditions, birds increase their leg surfacetemperature to above that of their plumage surface, expelling heat. By contrast,bill surface temperature remains approximately 2°C warmer than the plumagesurface, indicating consistent heat loss under almost all conditions. Poorerphysiological control of heat loss via bird bills likely entails stronger selectionfor shorter bills in cold climates. This could explain why bird bills show stron-ger latitudinal size clines than bird legs, with implications for predictingshape-shifting responses to climate change.
Enhjoy,
Fred
