Nature 255, 67 - 69 (01 May 1975); doi:10.1038/255067a0

Visual control of head movements during avian locomotion

MARK B. FRIEDMAN^*

Department of Psychology, University of Edinburgh, Edinburgh EH8 9TJ, UK
^*Present address: Department of Psychology, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213.

THE impression that pigeons, chickens, and many other common birds bob their heads backward and forward as they walk is compelling but illusory. In reality, the walking bird thrusts its head forward, then holds it nearly stationary while the neck retracts and the body catches up. The head moves backward and forward with respect to the body, but moves only forward in the environment. Although this was demonstrated on film more than 40 years ago¹, theorists concerned with the evolution of visual systems²⁻⁴ continue to suggest that a back and forth oscillation of the head is important in avian vision.

References

1.	Dunlap, K., and Mowrer, O. H., J. comp. Psych., 11, 99–113 (1930).
2.	Fremlin, J., New Scient., 56, 26–28 (1972).
3.	Kare, M. R., in Avian Physiology (edit. by Sturkie, P. D.), 406–418 (Cornell University Press, 1965).
4.	Walls, G. L., The Vertebrate Eye and its Adaptive Radiation (Cranbrook Institute, Bloomfield Hills, Michigan, 1942).
5.	Daanje, A., Behaviour, 3, 48–98 (1951).
6.	Huizinga, E., and van der Meulen, P., Ann. Otol. Rhinol. Laryngol., 60, 927–947 (1951).
7.	Friedman, M. B., in Neural and Endocrine Aspects of Behaviour in Birds (edit. by Wright, P., Caryl, P. G., and Vowles, D. M.), (Elsevier, in the press).
8.	Tauber, E. S., and Atkin, A., Science, 160, 1365–1367 (1968).
9.	Whiteside, T. C. D., J. Physiol., Lond. 188, 31P (1967).
10.	Trevarthen, C., in De L' Espace Corporel a L' Espace Ecologique (edit. by Bresson, F. et al.), 65–80 (Presses Universitaires de France, Paris, 1974).