Head bobbing and the body movement of little egrets (Egretta garzetta) during walking

Although previous studies have indicated that head bobbing of birds is an optokinetic movement, head bobbing can also be controlled by some biomechanical constraints when it occurs during walking. In the present study, the head bobbing, center of gravity, and body movements of little egrets (Egretta garzetta) during walking were examined by determination of the position of the center of gravity using carcasses and by motion analysis of video films of wild egrets during walking. The results showed that the hold phase occurs while the center of gravity is over the supporting foot during the single support phase. In addition, the peak speed of neck extension was coincident with the peak speed of the center of gravity. These movements are similar to those of pigeons, and suggest the presence of biomechanical constraints on the pattern of head bobbing and body movements during walking.

[1]  The head movement of walking birds. , 1967 .

[2]  B. Frost,et al.  Head-bobbing in pigeons: how stable is the hold phase? , 2000, The Journal of experimental biology.

[3]  H. P. Zeigier,et al.  Vision, brain, and behavior in birds. , 1994 .

[4]  B. Frost.  The Optokinetic Basis of Head-bobbing in the Pigeon , 1978 .

[5]  The head movement of walking birds. , 1967, The Journal of physiology.

[6]  S. Cramp.  Ostrich to ducks , 1977 .

[7]  P. Green,et al.  HEAD-BOBBING DURING WALKING, RUNNING AND FLYING: RELATIVE MOTION PERCEPTION IN THE PIGEON , 1988 .

[8]  D. W. Pratt.  Saccadic eye movements are coordinated with head movements in walking chickens. , 1982, The Journal of experimental biology.

[9]  Knight Dunlap,et al.  Head movements and eye functions of birds. , 1930 .

[10]  M. Friedman.  Visual control of head movements during avian locomotion , 1975, Nature.

[11]  I. Gibson,et al.  Isolation of DNA from B Chromosomes in Grasshoppers , 1970, Nature.

[12]  P. Green,et al.  Head-bobbing and head orientation during landing flights of pigeons , 1994, Journal of Comparative Physiology A.

[13]  M. Fujita.  Head bobbing and the movement of the centre of gravity in walking pigeons ( Columba livia ) , 2002 .

[14]  Rodger Kram,et al.  Simultaneous positive and negative external mechanical work in human walking. , 2002, Journal of biomechanics.

[15]  A. Daanje.  On Locomotory Movements in Birds and the Intention Movements Derived From Them , 1951 .

[16]  D. Weihs,et al.  Head stabilization in herons , 2001, Journal of Comparative Physiology A.