Birds have binocular vision, but most species can only rotate their eyes horizontally by 10°-20°. This limited eye movement explains the frequent and seemingly random head movements in birds. By moving their heads, birds compensate for their eyes’ lack of mobility, allowing them to have a clear stereoscopic view and accurately judge distances to external objects.
Additionally, these head movements help birds to detect motion and potential threats more effectively. By constantly changing the angle of their vision, birds can better spot predators or prey, ensuring their safety and improving their chances of survival. This constant scanning of their environment also aids in finding food and navigating through their surroundings.