Head-bobbing behavior in foraging whooping cranes favors visual fixation

Abstract

Many species of birds move their heads forward through a series of successive, fixed positions when walking. This unique ‘head-bobbing’ behavior stabilizes visual fields during body movement, preventing motion blur of the retinal image [1–3]. Gaze stabilization could be required for successful visual search, particularly for moving objects [4], but the time available for stabilization varies with walking speed. No direct evidence has been published showing that birds favor the stabilization phase while foraging either for moving or immobile food.