What action involving the bill serves as a clear cue for an observer to slowly retreat?

Answer

Snapping or clattering

The bird is known to use its bill for clattering when excited or agitated; when this is directed toward a perceived threat, it signifies clear irritation and warrants immediate slow retreat.

What action involving the bill serves as a clear cue for an observer to slowly retreat?

#Videos

A humble chat with a Shoebill. (Balaeniceps rex) - YouTube

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