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Head-bobbing is a common and characteristic behavior of walking birds. While the activity could have a relatively minor biomechanical function, for balance and stabilization of gait, head-bobbing is thought to be primarily a visual behavior in which fixation of gaze alternates with a forward movement that generates visual flow. We studied head-bobbing in locomoting whooping cranes (Grus americana) and sandhill cranes (Grus canadensis), using food strewn on the ground to motivate them to walk or run. When the cranes walked, head-bobbing proceeded in a four-step sequence that was closely linked to the stepping cycle. The time available for gaze stabilization decreased with travel speed, and running cranes did not head-bob at all. As a crane extended its bill towards the ground for food, it also exhibited a series of short head-bobs that were not associated with forward travel. Head-bobbing is a flexible behavior that varies with gait and with visual search, most notably as the cranes prepare to strike with the bill.

Diasporas and networks:the examples of Armenians and Jews .. 365 3.4.1 Trans-frontier mobility and the establishment of the mikra Armenikathemata -the career of Melias ...... 370 3.4.2 Trans-frontier mobility and the establishment of the mikra Armenikathemata -the law of emperor Nikephoros II Phokas against Armenian unsteadiness ... 373 3.4.3 Afemale Byzantine saint of Armenian background:Mary the Younger of Bizye .

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