Dieter asked ... why ostriches stick their heads in the sand

They don't. Ostriches have three main strategies when attacked. They can run away, they can kick, or they can try to hide (eg, when nursing the eggs). When hiding, they will sometimes lay flat on the ground, with the long neck and head also on the ground. In the rippling heat haze of their native Africa, they can look just like a grassy mound.

The myth that an ostrich will stick its head in the sand, in an effort to hide, may have begun with that great Roman thinker, Pliny the Elder (23-79AD), a man of intense curiosity about the world around him.

Before his death, in the eruption of Mt Vesuvius in 79 AD, Pliny had almost completed one of the earliest comprehensive encyclopaediae. His Natural History, in 37 books, was a remarkable attempt to summarise all the knowledge known to the Romans. So what did Pliny have to say of ostriches? In Book 10, Chapter 1, he writes, “…they imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed”.

Historians assume that this single sentence is the root of the myth about ostriches burying their head in the sand.

There is one interesting ostrich behaviour that comes close to burying their head in the sand. When ostriches feed, they sometimes lay their head flat on the ground to swallow sand and pebbles. The hard grit helps them to grind their food in their crop. From a distance, the ostrich looks like it’s burying its head in the sand.

Someone “hiding their head in the sand, like an ostrich” is said to be foolishly ignoring their problem, while hoping it will magically vanish.