Brain (hypothalamic) and cloacal temperatures were measured in heat-stressed Lesser Nighthawks (Chordeiles acutipennis), Mallards (Anas platyrhynchos), Pigeons (Columba livia), and White-Necked Ravens (Corvus cryptoleucus) and in one Roadrunner (Geococcyx californianus). Range of mean body masses was 0.047 to 1.156 kg.
In all these species brain temperatures were always below cloacal temperatures (Fig. 1). The body-to-brain temperature difference was maintained nearly constant within a species over a wide range of cloacal and air temperatures, and varied in magnitude from 0.80°C in the Roadrunner to 1.29°C in Mallards.
The presence of arete mirabile ophthalmicum was demonstrated in all five species. This rete may be associated with the observed pattern of brain temperature control.
The body-to-brain temperature difference may be important in avoiding brain damage during core hyperthermia.
Unable to display preview. Download preview PDF.
- Calder, W.A., King, J.R.: Thermal and caloric relations of birds. In: Avian biology, Vol 4 (D.S. Farner, J.R. King, eds.), pp. 259–413. New York: Academic Press 1974Google Scholar
- Cobb, S.: Observations on the comparative anatomy of the avian brain. Perspect. Biol. Med.3, 383–408 (1960)Google Scholar
- Eisenhart, C.: Expression of the uncertainties of final results. Science160, 1201–1204 (1968)Google Scholar
- Hayward, J.N., Baker, M.A.: A comparative study of the role of the cerebral arterial blood in the regulation of brain temperature in five mammals. Brain Res.16, 417–440 (1969)Google Scholar
- Kilgore, D.L., Jr., Bernstein, M.H., Schmidt-Nielsen, K.: Brain temperature in a large bird, the rhea. Amer. J. Physiol.225, 739–742 (1973)Google Scholar
- Lucas, A.M.: Avian functional anatomic problems. Fed. Proc.29 1641–1648 (1970)Google Scholar
- Richards, S.A.: Brain temperature and the cerebral circulation in the chicken. Brain Res.23, 265–268 (1970)Google Scholar
- Richards, S.A., Sykes, A.H.: Responses of the domestic fowl (Gallus domesticus) to occlusion of the cervical arteries and veins. Comp. Biochem. Physiol.21, 39–50 (1967)Google Scholar
- Scott, N.R., Tienhoven, A. van: Simultaneous measurement of hypothalamic and body temperatures and heart rate of poultry. Trans. Amer. Soc. Agr. Eng.14, 1027–1033 (1971)Google Scholar
- Sokal, R.R., Rohlf, F.J.: Biometry. San Francisco: W. H. Freeman 1969Google Scholar
- Taylor, C.R., Lyman, C.P.: Heat storage in running antelopes: independence of brain and body temperatures. Amer. J. Physiol.222, 114–117 (1972)Google Scholar
- Yoshikawa, T.: Atlas of the brains of domestic animals. University Park and London: Pennsylvania State University Press 1968Google Scholar