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Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert songbirds.
J Exp Biol 2017; 220(Pt 18):3290-3300JE

Abstract

We examined thermoregulatory performance in seven Sonoran Desert passerine bird species varying in body mass from 10 to 70 g - lesser goldfinch, house finch, pyrrhuloxia, cactus wren, northern cardinal, Abert's towhee and curve-billed thrasher. Using flow-through respirometry, we measured daytime resting metabolism, evaporative water loss and body temperature at air temperatures (Tair) between 30 and 52°C. We found marked increases in resting metabolism above the upper critical temperature (Tuc), which for six of the seven species fell within a relatively narrow range (36.2-39.7°C), but which was considerably higher in the largest species, the curve-billed thrasher (42.6°C). Resting metabolism and evaporative water loss were minimal below the Tuc and increased with Tair and body mass to maximum values among species of 0.38-1.62 W and 0.87-4.02 g H2O h-1, respectively. Body temperature reached maximum values ranging from 43.5 to 45.3°C. Evaporative cooling capacity, the ratio of evaporative heat loss to metabolic heat production, reached maximum values ranging from 1.39 to 2.06, consistent with known values for passeriforms and much lower than values in taxa such as columbiforms and caprimulgiforms. These maximum values occurred at heat tolerance limits that did not scale with body mass among species, but were ∼50°C for all species except the pyrrhuloxia and Abert's towhee (48°C). High metabolic costs associated with respiratory evaporation appeared to drive the limited heat tolerance in these desert passeriforms, compared with larger desert columbiforms and galliforms that use metabolically more efficient mechanisms of evaporative heat loss.

Authors+Show Affiliations

Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA ericsm@unm.edu.Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA. Department of Biology, University of Massachusetts, Amherst, MA 01003, USA.DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

28684465

Citation

Smith, Eric Krabbe, et al. "Avian Thermoregulation in the Heat: Resting Metabolism, Evaporative Cooling and Heat Tolerance in Sonoran Desert Songbirds." The Journal of Experimental Biology, vol. 220, no. Pt 18, 2017, pp. 3290-3300.
Smith EK, O'Neill JJ, Gerson AR, et al. Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert songbirds. J Exp Biol. 2017;220(Pt 18):3290-3300.
Smith, E. K., O'Neill, J. J., Gerson, A. R., McKechnie, A. E., & Wolf, B. O. (2017). Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert songbirds. The Journal of Experimental Biology, 220(Pt 18), pp. 3290-3300. doi:10.1242/jeb.161141.
Smith EK, et al. Avian Thermoregulation in the Heat: Resting Metabolism, Evaporative Cooling and Heat Tolerance in Sonoran Desert Songbirds. J Exp Biol. 2017 09 15;220(Pt 18):3290-3300. PubMed PMID: 28684465.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Avian thermoregulation in the heat: resting metabolism, evaporative cooling and heat tolerance in Sonoran Desert songbirds. AU - Smith,Eric Krabbe, AU - O'Neill,Jacqueline J, AU - Gerson,Alexander R, AU - McKechnie,Andrew E, AU - Wolf,Blair O, Y1 - 2017/07/06/ PY - 2017/04/13/received PY - 2017/07/04/accepted PY - 2017/7/8/pubmed PY - 2018/5/15/medline PY - 2017/7/8/entrez KW - Body temperature KW - Evaporative water loss KW - Heat tolerance limit KW - Passeriform birds KW - Passerines KW - Resting metabolic rate KW - Upper critical temperature SP - 3290 EP - 3300 JF - The Journal of experimental biology JO - J. Exp. Biol. VL - 220 IS - Pt 18 N2 - We examined thermoregulatory performance in seven Sonoran Desert passerine bird species varying in body mass from 10 to 70 g - lesser goldfinch, house finch, pyrrhuloxia, cactus wren, northern cardinal, Abert's towhee and curve-billed thrasher. Using flow-through respirometry, we measured daytime resting metabolism, evaporative water loss and body temperature at air temperatures (Tair) between 30 and 52°C. We found marked increases in resting metabolism above the upper critical temperature (Tuc), which for six of the seven species fell within a relatively narrow range (36.2-39.7°C), but which was considerably higher in the largest species, the curve-billed thrasher (42.6°C). Resting metabolism and evaporative water loss were minimal below the Tuc and increased with Tair and body mass to maximum values among species of 0.38-1.62 W and 0.87-4.02 g H2O h-1, respectively. Body temperature reached maximum values ranging from 43.5 to 45.3°C. Evaporative cooling capacity, the ratio of evaporative heat loss to metabolic heat production, reached maximum values ranging from 1.39 to 2.06, consistent with known values for passeriforms and much lower than values in taxa such as columbiforms and caprimulgiforms. These maximum values occurred at heat tolerance limits that did not scale with body mass among species, but were ∼50°C for all species except the pyrrhuloxia and Abert's towhee (48°C). High metabolic costs associated with respiratory evaporation appeared to drive the limited heat tolerance in these desert passeriforms, compared with larger desert columbiforms and galliforms that use metabolically more efficient mechanisms of evaporative heat loss. SN - 1477-9145 UR - https://www.unboundmedicine.com/medline/citation/28684465/Avian_thermoregulation_in_the_heat:_resting_metabolism_evaporative_cooling_and_heat_tolerance_in_Sonoran_Desert_songbirds_ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=28684465 DB - PRIME DP - Unbound Medicine ER -