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Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli).
J Exp Biol. 2016 07 15; 219(Pt 14):2137-44.JE

Abstract

Sandgrouse (Pterocliformes) are quintessential examples of avian adaptation to desert environments, but relatively little is known about the limits to their heat tolerance and evaporative cooling capacity. We predicted that evaporative cooling in Burchell's sandgrouse (Pterocles burchelli) is highly efficient and provides the basis for tolerance of very high air temperature (Ta). We measured body temperature (Tb), resting metabolic rate (RMR) and evaporative water loss (EWL) at Ta between 25°C and ∼58°C in birds exposed to successive increments in Ta Normothermic Tb averaged 39.0°C, lower than typical avian values. At Ta>34.5°C, Tb increased linearly to a maximum of 43.6°C at Ta=56°C. The upper critical limit of thermoneutrality (Tuc) was Ta=43.8°C, closely coinciding with the onset of panting and gular flutter. Above the Tuc, RMR increased 2.5-fold to 2.89 W at Ta=56°C, a fractional increase far exceeding that of many other species under comparable conditions. Rates of EWL increased rapidly at Ta>42.9°C to 7.84±0.90 g h(-1) at Ta=56°C, an 11-fold increase above minimal levels. Maximum evaporative cooling efficiency (ratio of evaporative heat loss to metabolic heat production) was 2.03, but could be as high as 2.70 if our assumption that the birds were metabolising lipids is incorrect. Thermoregulation at very high Ta in P. burchelli was characterised by large increases in RMR and EWL, and is much less efficient than in taxa such as columbids and caprimulgids.

Authors+Show Affiliations

DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa aemckechnie@zoology.up.ac.za.Department of Zoology, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031, South Africa.DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA.UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA.Department of Biology, University of Massachusetts, Amherst, MA 01003, USA.UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA.

Pub Type(s)

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

Language

eng

PubMed ID

27207634

Citation

McKechnie, Andrew E., et al. "Avian Thermoregulation in the Heat: Evaporative Cooling Capacity in an Archetypal Desert Specialist, Burchell's Sandgrouse (Pterocles Burchelli)." The Journal of Experimental Biology, vol. 219, no. Pt 14, 2016, pp. 2137-44.
McKechnie AE, Smit B, Whitfield MC, et al. Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli). J Exp Biol. 2016;219(Pt 14):2137-44.
McKechnie, A. E., Smit, B., Whitfield, M. C., Noakes, M. J., Talbot, W. A., Garcia, M., Gerson, A. R., & Wolf, B. O. (2016). Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli). The Journal of Experimental Biology, 219(Pt 14), 2137-44. https://doi.org/10.1242/jeb.139733
McKechnie AE, et al. Avian Thermoregulation in the Heat: Evaporative Cooling Capacity in an Archetypal Desert Specialist, Burchell's Sandgrouse (Pterocles Burchelli). J Exp Biol. 2016 07 15;219(Pt 14):2137-44. PubMed PMID: 27207634.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli). AU - McKechnie,Andrew E, AU - Smit,Ben, AU - Whitfield,Maxine C, AU - Noakes,Matthew J, AU - Talbot,William A, AU - Garcia,Mateo, AU - Gerson,Alexander R, AU - Wolf,Blair O, Y1 - 2016/05/09/ PY - 2016/02/27/received PY - 2016/05/02/accepted PY - 2016/5/22/entrez PY - 2016/5/22/pubmed PY - 2017/8/10/medline KW - Body temperature KW - Critical thermal maximum KW - Evaporative water loss KW - Hyperthermia KW - Pterocliformes KW - Upper critical limit of thermoneutrality SP - 2137 EP - 44 JF - The Journal of experimental biology JO - J. Exp. Biol. VL - 219 IS - Pt 14 N2 - Sandgrouse (Pterocliformes) are quintessential examples of avian adaptation to desert environments, but relatively little is known about the limits to their heat tolerance and evaporative cooling capacity. We predicted that evaporative cooling in Burchell's sandgrouse (Pterocles burchelli) is highly efficient and provides the basis for tolerance of very high air temperature (Ta). We measured body temperature (Tb), resting metabolic rate (RMR) and evaporative water loss (EWL) at Ta between 25°C and ∼58°C in birds exposed to successive increments in Ta Normothermic Tb averaged 39.0°C, lower than typical avian values. At Ta>34.5°C, Tb increased linearly to a maximum of 43.6°C at Ta=56°C. The upper critical limit of thermoneutrality (Tuc) was Ta=43.8°C, closely coinciding with the onset of panting and gular flutter. Above the Tuc, RMR increased 2.5-fold to 2.89 W at Ta=56°C, a fractional increase far exceeding that of many other species under comparable conditions. Rates of EWL increased rapidly at Ta>42.9°C to 7.84±0.90 g h(-1) at Ta=56°C, an 11-fold increase above minimal levels. Maximum evaporative cooling efficiency (ratio of evaporative heat loss to metabolic heat production) was 2.03, but could be as high as 2.70 if our assumption that the birds were metabolising lipids is incorrect. Thermoregulation at very high Ta in P. burchelli was characterised by large increases in RMR and EWL, and is much less efficient than in taxa such as columbids and caprimulgids. SN - 1477-9145 UR - https://www.unboundmedicine.com/medline/citation/27207634/Avian_thermoregulation_in_the_heat:_evaporative_cooling_capacity_in_an_archetypal_desert_specialist_Burchell's_sandgrouse__Pterocles_burchelli__ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=27207634 DB - PRIME DP - Unbound Medicine ER -