Journal of Comparative Physiology B

, Volume 164, Issue 6, pp 464–472

Thermoregulation in a large bird, the emu (Dromaius novaehollandiae)

  • S. K. Maloney
  • T. J. Dawson
Article

Abstract

The emu is a large, flightless bird native to Australia. Its habitats range from the high snow country to the arid interior of the continent. Our experiments show that the emu maintains a constant body temperature within the ambient temperature range-5 to 45°C. The males regulate their body temperature about 0.5°C lower than the females. With falling ambient temperature the emu regulates its body temperature initially by reducing conductance and then by increasing heat production. At-5°C the cost of maintaining thermal balance is 2.6 times basal metabolic rate. By sitting down and reducing heat loss from the legs the cost of homeothermy at-5°C is reduced to 1.5 times basal metabolic rate. At high ambient temperatures the emu utilises cutaneous evaporative water loss in addition to panting. At 45°C evaporation is equal to 160% of heat production. Panting accounts for 70% of total evaporation at 45°C. The cost of utilising cutaneous evaporation for the other 30% appears to be an increase in dry conductance.

Key words

Cutaneous evaporation Panting Ratite Thermoregulation Emu,Dromaius novaehollandiae 

Abbreviations

Ar

Effective radiating surface area

BMR

basal metabolic rate

Cdry

dry conductance

CEWL

cutaneous evaporative water loss

EHL

evaporative heat loss

EWL

evaporative water loss

FECO2

fractional concentration of CO2 in excurrent air

FFH2O

water content of chamber excurrent air

FEO2

fractional concentration of O2 in chamber excurrent air

FICO2

fractional concentration of CO2 in incurrent air

FIO2

fractional concentration of O2 in chamber incurrent air

MHP

metabolic heat production

MR

metabolic rate

REWL

respiratory evaporative water loss

RH

relative humidity

RQ

respiratory quotient\((\dot VCO_2 /\dot VO_2 )\);

SA

surface area

SEM

standard error of the mean

SNK

Student-Newman-Keuls multiple range test

STPD

standard temperature and pressure dry

Ta

ambient temperature(s)

Tb

body temperature(s)

Te

surface temperature(s)

\(\dot V\)

flow rate of air into the chamber

\(\dot VCO_2\)

carbon dioxide production

\(\dot VO_2\)

oxygen consumption

\(VP_{H_2 O}\)

vapour pressure of water

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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • S. K. Maloney
    • 1
  • T. J. Dawson
    • 1
  1. 1.School of Biological ScienceUniversity of New South WalesKensingtonAustralia
  2. 2.Brain Function Research UnitUniversity of the WitwatersrandParktownSouth Africa

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