Skip to main content

The thermal and energetic significance of clustering in the speckled mousebird, Colius striatus


The effect of clustering behaviour on metabolism, body temperature, thermal conductance and evaporative water loss was investigated in speckled mousebirds at temperatures between 5 and 36°C. Within the thermal neutral zone (approximately 30–35 °C) basal metabolic rate of clusters of two birds (32.5 J·g-1·h-1) and four birds (28.5 J·g-1·h-1) was significantly lower by about 11% and 22%, respectively, than that of individuals (36.4 J·g-1·h-1). Similarly, below the lower critical temperature, the metabolism of clusters of two and four birds was about 14% and 31% lower, respectively, than for individual birds as a result of significantly lower total thermal conductance in clustered birds. Body temperature ranged from about 36 to 41°C and was positively correlated with ambient temperature in both individuals and clusters, but was less variable in clusters. Total evaporative water loss was similar in individuals and clusters and averaged 5–6% of body weight per day below 30°C in individuals and below 25°C in clusters. Above these temperatures total evaporative water loss increased and mousebirds could dissipate between 80 and 90% of their metabolic heat production at ambient temperatures between 36 and 39°C. Mousebirds not only clustered to sleep between sunset and sunrise but were also observed to cluster during the day, even at high ambient temperature. Whereas clustering at night and during cold, wet weather serves a thermoregulatory function, in that it allows the brrds to maintain body temperature at a reduced metabolic cost, clustering during the day is probably related to maintenance of social bonds within the flock.

This is a preview of subscription content, access via your institution.



basal metabolic rate


body weight

C totab :

total thermal conductance


evaporative water loss

M :



relative humidity

T a :

ambient temperature

T b :

body temperature

T ch :

chamber temperature

T cl :

cluster temperature


total evaporative water loss


lower critical temperature


thermal neutral zone


  1. Aschoff J (1981) Thermal conductance in mammals and birds. Comp Biochem Physiol 69A:611–619

    Google Scholar 

  2. Aschoff J, Pohl H (1970) Der Runeumasatz von Vögeln als Funktion der Tageszeit und der Körpergröße. J Ornithol 111:38–47

    Google Scholar 

  3. Bartholomew GA, Trost CH (1970) Temperature regulation in the speckled mousebird, Colius striatus. Condor 72:141–146

    Google Scholar 

  4. Calder WA, King JR (1974) Thermal and caloric relations of birds. In: Farner DS, King JR (eds) Avian biology, vol 4. Academic Press, New York, pp 259–413

    Google Scholar 

  5. Chaplin SB (1982) The energetic significance of huddling behavior in common bushtits (Psaltriparus minimus). Auk 99:424–430

    Google Scholar 

  6. Dawson WR, Hudson JW (1970) Birds. In: Whittow GC (ed) Comparative physiology of thermoregulation, vol 1. Academic Press, New York, pp 223–310

    Google Scholar 

  7. Elkins N (1983) Weather and bird behaviour. T and AD Poyser Ltd., Calton England

    Google Scholar 

  8. Fry CH, Keith S, Urban EK (1988) The birds of Africa, vol 3. Academic Press, New York

    Google Scholar 

  9. Hoffmann R, Prinzinger R (1984) Torpor und Nahrungsausnutzung bei 4 Mausvogelarten (Coliiformes). J Ornithol 125:225–237

    Google Scholar 

  10. Levy A (1964) The accuracy of the bubble meter method for gas flow measurements. J Sci Instrum 41:449–453

    Google Scholar 

  11. Le Maho Y (1977) The emperor penguin: a strategy to live and breed in the cold. Am Sci 65:680–693

    Google Scholar 

  12. Ligon JD, Ligon SH (1978) The communal social system of the green woodhoopoe in Kenya. Living Bird 17:159–197

    Google Scholar 

  13. Ligon JD, Carey C, Ligon SH (1988) Cavity roosting and cooperative breeding in the green woodhoopoe reflect a physiological trait. Auk 105:123–127

    Google Scholar 

  14. McAtee WL (1947) Torpidity in birds. Am Midl Nat 30:191–206

    Google Scholar 

  15. McNab BK (1980) On estimating thermal conductance in endotherms. Physiol Zool 53:145–156

    Google Scholar 

  16. Pearson OP (1960) The oxygen consumption and bioenergetics of harvest mice. Physiol Zool 33:152–160

    Google Scholar 

  17. Prinzinger R (1988) Energy metabolism, body temperature and breathing parameters in non-torpid blue-naped mousebirds, Urocolius macrourus. J Comp Physiol B 157:801–806

    Google Scholar 

  18. Prinzinger R, Goppel R, Lorenz A, Kulzer E (1981) Body temperature and metabolism in the red-backed mousebird (Colius castanotus) during fasting and torpor. Comp Biochem Physiol 69A:689–692

    Google Scholar 

  19. Prinzinger R, Preßmar A, Schleucher E (1991) Body temperature in birds. Comp Biochem Physiol 99A:499–506

    Google Scholar 

  20. Reinertsen RE (1983) Nocturnal hypothermia and its energetic significance for small birds living in the Arctic and subarctic regions: a review. Polar Res 1:269–284

    Google Scholar 

  21. Rowan MK (1967) A study of the colies of southern Africa. Ostrich 38:63–115

    Google Scholar 

  22. Simmons KEL (1986) The sunning behaviour of birds. The Bristol Ornithological Club, Bristol, UK

    Google Scholar 

  23. Vogt FD, Lynch GR (1982) Influence of ambient temperature, nest availability, huddling and daily torpor on energy expenditure in the white-footed mouse (Peromyscus leucopus). Physiol Zool 55:56–63

    Google Scholar 

  24. Williams JB, du Plessis M, Siegfried WR (1991) Green wood-hoopoes (Phoeniculus purpureus) and obligate cavity roosting provide a test of the thermal insufficiency hypothesis. Auk 108:285–293

    Google Scholar 

  25. Withers PC (1977) Measurement of VO2, VCO2 and evaporative water loss with a flow-through mask. J Appl Physiol 42:120–123

    Google Scholar 

  26. Withers PC, Jarvis JUM (1980) The effect of huddling on thermoregulation and oxygen consumption of the naked molerat. Comp Biochem Physiol 66A:215–219

    Google Scholar 

  27. Yamagishi S, Kabango G (1986) The social organisation of the speckled mousebird, Colius striatus, during the dry season in tropical Africa. Ecol Res 1:329–334

    Google Scholar 

  28. Zar JH (1974) Biostatistical analysis. Prentice-Hall Inc., New Jersey, USA

    Google Scholar 

Download references

Author information



Corresponding author

Correspondence to C. R. Brown.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Brown, C.R., Foster, G.G. The thermal and energetic significance of clustering in the speckled mousebird, Colius striatus . J Comp Physiol B 162, 658–664 (1992).

Download citation

Key words

  • Clustering behaviour
  • Metabolism
  • Thermoregulation
  • Evaporative water loss
  • Thermal conductance
  • Mousebird, Colius striatus