The impact of humidity on evaporative cooling in small desert birds exposed to high air temperatures

Show simple item record Gerson, Alexander R. Smith, Eric Krabbe Smit, Ben McKechnie, Andrew E. Wolf, Blair O. 2015-01-30T08:21:51Z 2015-01-30T08:21:51Z 2014-11
dc.description.abstract Environmental temperatures that exceed body temperature (Tb) force endothermic animals to rely solely on evaporative cooling to dissipate heat. However, evaporative heat dissipation can be drastically reduced by environmental humidity, imposing a thermoregulatory challenge. The goal of this study was to investigate the effects of humidity on the thermoregulation of desert birds and to compare the sensitivity of cutaneous and respiratory evaporation to reduced vapor density gradients. Rates of evaporative water loss, metabolic rate, and Tb were measured in birds exposed to humidities ranging from ∼2 to 30 g H2O m23 (0%–100% relative humidity at 307C) at air temperatures between 447 and 567C. In sociable weavers, a species that dissipates heat primarily through panting, rates of evaporative water loss were inhibited by as much as 36% by high humidity at 487C, and these birds showed a high degree of hyperthermia. At lower temperatures (407–447C), evaporative water loss was largely unaffected by humidity in this species. In Namaqua doves, which primarily use cutaneous evaporation, increasing humidity reduced rates of evaporative water loss, but overall rates of water loss were lower than those observed in sociable weavers. Our data suggest that cutaneous evaporation is more efficient than panting, requiring less water to maintain Tb at a given temperature, but panting appears less sensitive to humidity over the air temperature range investigated here. en_ZA
dc.description.librarian tm2015 en_ZA
dc.description.sponsorship DST/National Research Foundation Centre of Excellence en_ZA
dc.description.uri http://www.journals.uchicago.edutoc/pbz/ en_ZA
dc.identifier.citation Gerson, AR, Smith, EK, Smit, B, McKechnie, AE & Wolf, BO 2014, 'The impact of humidity on evaporative cooling in small desert birds exposed to high air temperatures', Physiological and Biochemical Zoology, vol. 87, no. 6, pp. 782–795. en_ZA
dc.identifier.issn 1522-2152 (print)
dc.identifier.issn 1537-5293 (online)
dc.identifier.other 10.1086/678956
dc.language.iso en en_ZA
dc.publisher University of Chicago Press en_ZA
dc.rights © 2014 De Vos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License. en_ZA
dc.subject Humidity en_ZA
dc.subject Environmental temperatures en_ZA
dc.subject Thermoregulatory challenge en_ZA
dc.subject Namaqua doves en_ZA
dc.subject High air temperatures en_ZA
dc.subject Body temperature (Tb) en_ZA
dc.title The impact of humidity on evaporative cooling in small desert birds exposed to high air temperatures en_ZA
dc.type Article en_ZA

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