Thermoregulation in desert birds : scaling and phylogenetic variation in heat tolerance and evaporative cooling

dc.contributor.authorMcKechnie, Andrew E.
dc.contributor.authorGerson, Alexander R.
dc.contributor.authorWolf, Blair O.
dc.contributor.emailandrew.mckechnie@up.ac.zaen_US
dc.date.accessioned2022-05-06T10:24:05Z
dc.date.available2022-05-06T10:24:05Z
dc.date.issued2021-02
dc.description.abstractEvaporative heat dissipation is a key aspect of avian thermoregulation in hot environments.We quantified variation in avian thermoregulatory performance at high air temperatures (Ta) using published data on body temperature (Tb), evaporative water loss (EWL) and resting metabolic rate (RMR) measured under standardized conditions of very low humidity in 56 arid-zone species. Maximum Tb during acute heat exposure varied from 42.5±1.3°C in caprimulgids to 44.5±0.5°C in passerines. Among passerines, both maximum Tb and the difference between maximum and normothermic Tb decreased significantly with body mass (Mb). Scaling exponents for minimum thermoneutral EWL and maximum EWL were 0.825 and 0.801, respectively, even though evaporative scope (ratio of maximum to minimum EWL) varied widely among species. Upper critical limits of thermoneutrality (Tuc) varied by >20°C and maximumRMR during acute heat exposure scaled toMb 0.75 in both the overall data set and among passerines. The slope of RMR at Ta>Tuc increased significantly with Mb but was substantially higher among passerines, which rely on panting, comparedwith columbids, in which cutaneous evaporation predominates. Our analysis supports recent arguments that interspecific within-taxon variation in heat tolerance is functionally linked to evaporative scope and maximum ratios of evaporative heat loss (EHL) to metabolic heat production (MHP). We provide predictive equations for most variables related to avian heat tolerance. Metabolic costs of heat dissipation pathways, rather than capacity to increase EWL above baseline levels, appear to represent the major constraint on the upper limits of avian heat tolerance.en_US
dc.description.departmentZoology and Entomologyen_US
dc.description.librarianam2022en_US
dc.description.sponsorshipThe National Research Foundation and the National Science Foundation.en_US
dc.description.urihttp://jeb.biologists.orgen_US
dc.identifier.citationMckechnie, A.E., Gerson, A.R. & Wolf, B.O. 2021, 'Thermoregulation in desert birds : scaling and phylogenetic variation in heat tolerance and evaporative cooling', Journal of Experimental Biology, vol. 224, suppl. 1, art. jeb229211, pp. 1-16.en_US
dc.identifier.issn0022-0949 (print)
dc.identifier.issn1477-9145 (online)
dc.identifier.other10.1242/jeb.229211
dc.identifier.urihttps://repository.up.ac.za/handle/2263/85133
dc.language.isoenen_US
dc.publisherCompany of Biologistsen_US
dc.rights© 2021. Published by The Company of Biologists Ltd.en_US
dc.subjectBody temperatureen_US
dc.subjectGular flutteren_US
dc.subjectHyperthermiaen_US
dc.subjectMetabolic rateen_US
dc.subjectPantingen_US
dc.subjectEvaporative water loss (EWL)en_US
dc.subjectResting metabolic rateen_US
dc.subjectThermoregulation
dc.subjectDesert birds
dc.titleThermoregulation in desert birds : scaling and phylogenetic variation in heat tolerance and evaporative coolingen_US
dc.typeArticleen_US

Files

Original bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
McKechnie_Thermoregulation_2021.pdf
Size:
1.79 MB
Format:
Adobe Portable Document Format
Description:
Article

License bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
1.75 KB
Format:
Item-specific license agreed upon to submission
Description: