early 13c., from Old French ostruce "ostrich" (Modern French autruche) and Medieval Latin ostrica, ostrigius, all from Vulgar Latin avis struthio, from Latin avis "bird" (from PIE root *awi- "bird") + Late Latin struthio "ostrich," from Greek strouthion "ostrich," from strouthos megale "big sparrow," perhaps from PIE *trozdo- "thrush" (see thrush (n.1)). The Greeks also knew the bird as strouthokamelos "camel-sparrow," for its long neck. Among its proverbial peculiarities are indiscriminate voracity (especially a habit of swallowing iron and stone to aid digestion), want of regard for its eggs, and a tendency to hide its head when pursued.Ostriches do put their heads in the sand, but ostrich farmers say they do this in search of something to eat.
Like the Austridge, who hiding her little head, supposeth her great body obscured. [1623, recorded in OED]