Avian thermoregulation in the heat : phylogenetic variation among avian orders in evaporative cooling capacity and heat tolerance

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dc.contributor.author Smit, Ben
dc.contributor.author Whitfield, Maxine
dc.contributor.author Talbot, William A.
dc.contributor.author Gerson, Alexander R.
dc.contributor.author McKechnie, Andrew E.
dc.contributor.author Wolf, Blair O.
dc.date.accessioned 2018-08-24T10:26:01Z
dc.date.issued 2018-03
dc.description.abstract Little is known about the phylogenetic variation of avian evaporative cooling efficiency and heat tolerance in hot environments. We quantified thermoregulatory responses to high air temperature (Ta) in ∼100-g representatives of three orders, namely, the African cuckoo (Cuculus gularis, Cuculiformes), lilac-breasted roller (Coracias caudatus, Coraciiformes) and Burchell’s starling (Lamprotornis australis, Passeriformes). All three species initiated respiratory mechanisms to increase evaporative heat dissipation when body temperature (Tb) approached 41.5°C in response to increasing Ta, with gular flutter observed in cuckoos and panting in rollers and starlings. Resting metabolic rate and evaporative water loss increased by quantitatively similar magnitudes in all three species, although maximum rates of evaporative water loss were proportionately lower in starlings. Evaporative cooling efficiency [defined as the ratio of evaporative heat loss (EHL) to metabolic heat production (MHP)] generally remained below 2.0 in cuckoos and starlings, but reached a maximum of ∼3.5 in rollers. The high value for rollers reveals a very efficient evaporative cooling mechanism, and is similar to EHL/MHP maxima for similarly sized columbids which very effectively dissipate heat via cutaneous evaporation. This unexpected phylogenetic variation among the orders tested in the physiological mechanisms of heat dissipation is an important step toward determining the evolution of heat tolerance traits in desert birds. en_ZA
dc.description.department Zoology and Entomology en_ZA
dc.description.embargo 2019-03-01
dc.description.librarian am2018 en_ZA
dc.description.sponsorship This material is based on work supported by the National Science Foundation under IOS-1122228 to B.O.W. en_ZA
dc.description.sponsorship The National Science Foundation under IOS-1122228 to B.O.W. en_ZA
dc.description.uri http://jeb.biologists.org en_ZA
dc.identifier.citation Smit, B., Whitfield, M.C., Talbot, W.A. et al. 2018, 'Avian thermoregulation in the heat : phylogenetic variation among avian orders in evaporative cooling capacity and heat tolerance', Journal of Experimental Biology, vol. 221, no. 6, art. no. jeb.174870, pp. 1-11. en_ZA
dc.identifier.issn 0022-0949 (print)
dc.identifier.issn 1477-9145 (online)
dc.identifier.other 10.1242/jeb.174870
dc.identifier.uri http://hdl.handle.net/2263/66319
dc.language.iso en en_ZA
dc.publisher Company of Biologists en_ZA
dc.rights © 2018. Published by The Company of Biologists Ltd. en_ZA
dc.subject Heat dissipation en_ZA
dc.subject Upper criti callimits of thermoneutrality en_ZA
dc.subject Panting en_ZA
dc.subject Gular flutter en_ZA
dc.subject Evaporative heat loss (EHL) en_ZA
dc.subject Body temperature (Tb) en_ZA
dc.subject Metabolic heat production (MHP) en_ZA
dc.subject Ventilation en_ZA
dc.subject Environment en_ZA
dc.subject Doves en_ZA
dc.subject Reveals en_ZA
dc.subject Birds en_ZA
dc.subject Zone passerine en_ZA
dc.subject Oxygen consumption en_ZA
dc.subject Resting metabolism en_ZA
dc.subject Temperature regulation en_ZA
dc.subject Water loss en_ZA
dc.title Avian thermoregulation in the heat : phylogenetic variation among avian orders in evaporative cooling capacity and heat tolerance en_ZA
dc.type Article en_ZA


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