At the edge of a slough I came across a group of young Mallard ducklings, far enough along that they don't look like fluff-balls anymore, yet still too young to have learned to quack. "Peep, peep, peep." They eyed me nervously, but didn't move, and then their mom (I assume it was their mother) swam past about 10 metres out, and several lowered their heads. (At her?) I was only a few metres from the ducklings, and slightly above on a boardwalk.
I've not seen this before, and couldn't find anything relevant on duckling postures. Fear? Begging?
A few opened their bills without emitting audible sounds. Anyone have a clue what was going on?