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dc.contributor.author | McWhorter, Todd J.![]() |
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dc.contributor.author | Gerson, Alexander R.![]() |
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dc.contributor.author | Talbot, William A.![]() |
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dc.contributor.author | Smith, Eric Krabbe![]() |
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dc.contributor.author | McKechnie, Andrew E.![]() |
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dc.contributor.author | Wolf, Blair O.![]() |
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dc.date.accessioned | 2018-08-24T10:14:33Z | |
dc.date.issued | 2018-03 | |
dc.description.abstract | Avian orders differ in their thermoregulatory capabilities and tolerance of high environmental temperatures. Evaporative heat loss, and the primary avenue whereby it occurs, differs amongst taxa. Although Australian parrots (Psittaciformes) have been impacted by mass mortality events associated with extreme weather events (heat waves), their thermoregulatory physiology has not been well-characterized. We quantified the upper limits to thermoregulation under extremely hot conditions in two Australian parrots: the mulga parrot (Psephotellus varius; ~55 g) and the galah (Eolophus roseicapilla; ~265 g). At air temperatures (Ta) exceeding body temperature (Tb), both species showed increases in Tb to maximum values around 43–44°C, accompanied by rapid increases in resting metabolic rate above clearly defined upper critical limits of thermoneutrality and increases in evaporative water loss (EWL) to levels equivalent to 700–1000% of baseline rates at thermoneutral Ta. Maximum cooling capacity, quantified as the fraction of metabolic heat production dissipated evaporatively, ranged from 1.71 to 1.79, consistent with the known range for parrots, similar to the corresponding range in passerines, and well below the corresponding ranges for columbids and caprimulgids. Heat tolerance limit (HTL, the maximum Ta tolerated) ranged from 44-55°C, similar to the range reported for passerines, but lower than reported for columbids and caprimulgids. Our data suggest that heat tolerance in parrots is similar to that of passerines. We argue that understanding how thermoregulatory capacity and heat tolerance vary across avian orders is vital for predicting how climate change and the associated increase in frequency of extreme weather events may impact avian populations in the future. | 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 (IOS-1122228 to B.O.W.). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. | en_ZA |
dc.description.uri | http://jeb.biologists.org | en_ZA |
dc.identifier.citation | McWhorter, T.J., Gerson, A.R., Talbot, W.A. et al. 2018, 'Avian thermoregulation in the heat : evaporative cooling capacity and thermal tolerance in two Australian parrots', Journal of Experimental Biology, vol. 221, no. 6, art. no. jeb.168930, pp. 1-10. | en_ZA |
dc.identifier.issn | 0022-0949 (print) | |
dc.identifier.issn | 1477-9145 (online) | |
dc.identifier.other | 10.1242/jeb.168930 | |
dc.identifier.uri | http://hdl.handle.net/2263/66318 | |
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 | Hyperthermia | en_ZA |
dc.subject | Psittaciformes | en_ZA |
dc.subject | Respiratory evaporative water loss | en_ZA |
dc.subject | Resting metabolic rate | en_ZA |
dc.subject | Body temperature (Tb) | en_ZA |
dc.subject | Evaporative water loss (EWL) | en_ZA |
dc.subject | Heat tolerance limit (HTL) | en_ZA |
dc.subject | Doves | en_ZA |
dc.subject | Biology | en_ZA |
dc.subject | Resting metabolism | en_ZA |
dc.subject | Budgerigars (Melopsittacus undulatus) | en_ZA |
dc.subject | Physiological adjustments | en_ZA |
dc.subject | Desert birds | en_ZA |
dc.subject | Climate change | en_ZA |
dc.subject | Temperature regulation | en_ZA |
dc.subject | Australian parrots | en_ZA |
dc.subject | Galah (Eolophus roseicapilla) | en_ZA |
dc.subject | Mulga parrot (Psephotellus varius) | en_ZA |
dc.title | Avian thermoregulation in the heat : evaporative cooling capacity and thermal tolerance in two Australian parrots | en_ZA |
dc.type | Article | en_ZA |