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Food, fibre and pharmaceuticals from animals
REVIEW

Thermoregulation in ratites: a review

Shane K. Maloney
+ Author Affliations
- Author Affliations

Physiology, School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Email: shanem@cyllene.uwa.edu.au

Australian Journal of Experimental Agriculture 48(10) 1293-1301 https://doi.org/10.1071/EA08142
Submitted: 13 April 2008  Accepted: 23 June 2008   Published: 11 September 2008

Abstract

Laboratory and free-ranging studies on the emu, ostrich and kiwi show ratites to be competent homeotherms. While body temperature and basal metabolic rate are lower in ratites than other birds, all of the thermoregulatory adaptations present in other birds are well established in ratites. The thermoneutral zone has been established for the emu and kiwi, and extends to 10°C. Below that zone, homeothermy is achieved via the efficient use of insulation and elevated metabolic heat production. In the heat, emus and ostriches increase respiratory evaporative water loss and use some cutaneous water loss. Respiratory alkalosis is avoided by reducing tidal volume. In severe heat, tidal volume increases, but the emu becomes hypoxic and hypocapnic, probably by altering blood flow to the parabronchi, resulting in ventilation/perfusion inhomogeneities. Ostriches are capable of uncoupling brain temperature from arterial blood temperature, a phenomenon termed selective brain cooling. This mechanism may modulate evaporative effector responses by manipulating hypothalamic temperature, as in mammals. The implications of thermal physiology for ratite production systems include elevated metabolic costs for homeothermy at low ambient temperature. However, the emu and ostrich are well adapted to high environmental temperatures.


Acknowledgements

Most of the work described in this review was undertaken in collaboration with Professor Terry Dawson and funded by the Australian Research Council. The author thanks the anonymous referees and editor for their many suggestions that improved the manuscript.


References


Arad Z (1990) Avian brain cooling – a review. Journal of Basic and Clinical Physiology 1, 241–254.
CAS |
open url image1

Arad Z, Gavriellevin I, Eylath U, Marder J (1987) Effect of dehydration on cutaneous water evaporation in heat-exposed pigeons (Columba livia). Physiological Zoology 60, 623–630. open url image1

Aschoff J, Pohl H (1970) Rhythmic variations in energy metabolism. Federation Proceedings 29, 1541–1542.
CAS | PubMed |
open url image1

Benedict FG, Fox EL (1927) The gaseous metabolism of large wild birds under aviary life. Proceedings of the American Philosophical Society 66, 511–534.
CAS |
open url image1

Buttemer WA, Astheimer LB, Dawson TJ (1988) Thermal and water relations of emu eggs during natural incubation. Physiological Zoology 61, 483–494. open url image1

Calder WA, Dawson TJ (1978) Resting metabolic rates of ratite birds: the kiwis and the emu. Comparative Biochemistry and Physiology. Part A, Physiology 60, 479–481.
CrossRef | open url image1

Chappell MA, Souza SL (1988) Thermoregulation, gas exchange and ventilation in Adelie penguins (Pygoscelis adeliae). Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 157, 783–790.
CrossRef | CAS | PubMed | open url image1

Crawford EC, Lasiewski RC (1968) Oxygen consumption and respiratory evaporation of the emu and rhea. The Condor 70, 333–339.
CrossRef | open url image1

Crawford EC, Schmidt-Nielsen K (1967) Temperature regulation and evaporative cooling in the ostrich. The American Journal of Physiology 212, 347–353.
PubMed |
open url image1

Dzialowski EM, Burggren WW, Komoro T, Tazawa H (2007) Development of endothermic metabolic response in embryos and hatchlings of the emu (Dromaius novaehollandiae). Respiratory Physiology & Neurobiology 155, 286–292.
CrossRef | CAS | PubMed | open url image1

Felsenstein J (1985) Phylogenies and the comparative method. American Naturalist 125, 1–15.
CrossRef | open url image1

Freitag S, Robinson TJ (1993) Phylogeographic patterns in mitochondrial-DNA of the ostrich (Struthio camelus). The Auk 110, 614–622. open url image1

Fuller A, Kamerman PR, Maloney SK, Mitchell G, Mitchell D (2003) Variability in brain and arterial blood temperatures in free-ranging ostriches in their natural habitat. The Journal of Experimental Biology 206, 1171–1181.
CrossRef | PubMed | open url image1

Fuller A, Meyer LCR, Mitchell D, Maloney SK (2007) Dehydration increases the magnitude of selective brain cooling independently of core temperature in sheep. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 293, R438–R446.
CAS | PubMed |
open url image1

Garland JT, Ives AR (2000) Using the past to predict the present: confidence intervals for regression equations in phylogenetic comparative methods. American Naturalist 155, 346–364.
CrossRef | PubMed | open url image1

Gill FB (1995) ‘Ornithology.’ (WH Freeman: New York)

Hales JRS, Webster MED (1967) Respiratory function during thermal tachypnoea in sheep. The Journal of Physiology 190, 241–260.
CAS | PubMed |
open url image1

IUPS Thermal Commission (2001) Glossary of terms for thermal physiology: third edition. Japanese Journal of Physiology 51, 245–280. open url image1

Jessen C (2001) ‘Temperature regulation in humans and other mammals.’ (Springer-Verlag: Berlin)

Jessen C, Hales JRS, Molyneux GS (1982) Hypothalamic thermosensitivity in an emu, Dromiceius novaehollandiae. Pflugers Archive – European Journal of Physiology 393, 278–280.
CAS | CrossRef |
open url image1

Johansen K, Bech C (1983) Heat conservation during cold exposure in birds (vasomotor and respiratory implications). Polar Research 1, 259–268.
CrossRef | open url image1

Jones JH (1982) Pulmonary blood flow distribution in panting ostriches. Journal of Applied Physiology 53, 1411–1417.
CAS | PubMed |
open url image1

Jones JH, Grubb B, Schmidt-Nielsen K (1983) Panting in the emu causes arterial hypoxernia. Respiration Physiology 54, 189–195.
CrossRef | CAS | PubMed | open url image1

Kilgore DL, Bernstein MH, Schmidt-Nielsen K (1973) Brain temperature in a large bird, the rhea. The American Journal of Physiology 225, 739–742.
PubMed |
open url image1

Kilgore DL, Bernstein MH, Hudson DM (1976) Brain temperatures in birds. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 110, 209–215.
CrossRef | open url image1

Lasiewski RC, Dawson WR (1967) A re-examination of the relation between standard metabolic rate and body weight in birds. The Condor 69, 13–23.
CrossRef |
open url image1

Louw GN, Belonje PC, Coetzee HJ (1969) Renal function, respiration, heart rate and thermoregulation in the ostrich (Struthio camelus). Scientific Papers of the Namib Desert Research Station 42, 43–54. open url image1

Maloney SK, Dawson TJ (1993) Sexual dimorphism in basal metabolism and body temperature of a large bird, the emu. The Condor 95, 1034–1037.
CrossRef | open url image1

Maloney SK, Dawson TJ (1994a) Thermoregulation in a large bird, the emu (Dromaius novaehollandiae). Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 164, 464–472.
CrossRef | open url image1

Maloney SK, Dawson TJ (1994b) Ventilatory accommodation of oxygen demand and respiratory water loss in a large bird, the emu (Dromaius novaehollandiae), and a re-examination of ventilatory allometry for birds. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 164, 473–481.
CrossRef | open url image1

Maloney SK, Dawson TJ (1998) Changes in pattern of heat loss at high ambient temperature caused by water deprivation in a large flightless bird, the emu. Physiological Zoology 71, 712–719.
CAS | PubMed |
open url image1

Maloney SK, Mitchell D, Blache D (2007) The contribution of carotid rete variability to brain temperature variability in sheep in a thermoneutral environment. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 292, R1298–R1305.
CAS | PubMed |
open url image1

Marder J, Arad Z (1989) Panting and acid-base regulation in heat stressed birds. Comparative Biochemistry and Physiology. Physiology 94, 395–400.
CrossRef | CAS | open url image1

Marder J, Gavrieli-Levin I (1987) The heat-acclimated pigeon: an ideal physiological model for a desert bird. Journal of Applied Physiology 69, 952–958. open url image1

Marder J, Raber P (1989) Beta-adrenergic control of trans-cutaneous evaporative cooling mechanisms in birds. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 159, 97–103.
CrossRef | CAS | open url image1

McKechnie A, Wolf B (2004) The allometry of avian basal metabolic rate: good predictions need good data. Physiological and Biochemical Zoology 77, 502–521.
CrossRef | PubMed | open url image1

McNab BK (1996) Metabolism and temperature regulation of kiwis (Apterygidae). The Auk 113, 687–692. open url image1

Menon GK, Baptista LF, Brown BE, Elias PM (1989) Avian epidermal differentiation. II. Adaptive response of permeability barrier to water-deprivation and replenishment. Tissue & Cell 21, 83–92.
CrossRef | CAS | PubMed | open url image1

Mindell DP, Sorenson MD, Dimcheff DE, Hasegawa M, Ast JC, Yuri T (1999) Interordinal relationships of birds and other reptiles based on whole mitochondrial genomes. Systematic Biology 48, 138–152.
CrossRef | CAS | PubMed | open url image1

Mitchell D, Maloney SK, Jessen C, Laburn HP, Kamerman PR, Mitchell G, Fuller A (2002) Adaptive heterothermy and selective brain cooling in arid-zone mammals. Comparative Biochemistry and Physiology. B, Comparative Biochemistry 131, 571–585.
CrossRef | open url image1

Ophir E, Peltonen L, Arieli Y (2003) Cutaneous water evaporation in the heat-acclimated rock pigeon (Columba livia) – physiological and biochemical aspects. Israel Journal of Zoology 49, 131–148.
CrossRef | open url image1

Phillips PK, Heath JE (1992) Heat-exchange by the pinna of the African elephant (Loxodonta africana). Comparative Biochemistry and Physiology. Physiology 101, 693–699.
CrossRef | CAS | open url image1

Richards SA (1970) The biology and comparative physiology of thermal panting. Biological Reviews of the Cambridge Philosophical Society 45, 223–264.
CrossRef | CAS | PubMed | open url image1

Schmidt-Nielsen K, Lasiewski RC, Bretz WL, Kanwisher J, Cohn JE (1969) Temperature regulation and respiration in the ostrich The Condor 71, 341–352.
CrossRef | open url image1

Sibley CG, Monroe BL (1990) ‘Distribution and taxonomy of birds of the world.’ (Yale University Press: New Haven, CT)

Simon E, Pierau FK, Taylor DCM (1986) Central and peripheral thermal control of effectors in homeothermic temperature regulation. Physiological Reviews 66, 235–300.
CAS | PubMed |
open url image1

van Tuinen M, Sibley CG, Hedges SB (2000) The early history of modern birds inferred from DNA sequences of nuclear and mitochondrial ribosomal genes. Molecular Biology and Evolution 17, 451–457.
CAS | PubMed |
open url image1

Withers PC (1983) Energy, water, and solute balance of the ostrich Struthio camelus. Physiological Zoology 56, 568–579. open url image1

Withers PC, Williams JB (1990) Metabolic and respiratory physiology of an arid-adapted Australian bird, the Spinifex pigeon. The Condor 92, 961–969.
CrossRef | open url image1

Withers PC, Siegfried WR, Louw GN (1981) Desert ostrich exhales unsaturated air. South African Journal of Science 77, 569–570. open url image1








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