"It couldn't have been hatched by any of the hens" I thought.
I watched it cheeping and chirruping all over the place. Eventually it disappeared.
When I looked for it some while later I found it back with its mum - not with a hen but with one of the Ducks in her nest.
Is this a first? A chick hatching from a duck's nest??? Anyway, clearly the little chick knew its mum was a duck because the following day it spent much of its time running around after any and every duck (its 'mum' still being on the nest waiting to hatch her real chicks) asking "Are you my mummy?".
The drakes got most impatient: every time they stopped moving around the little chick would try to snuggle underneath them and as soon as that happened, off waddled the drake in disgust..... and then the chick would pursue some other hapless drake--- to the same ill effect.
I was amazed that it survived even the first night! Yet by Tuesday there it was still cheeping all over the place, inside and out, following each and every duck asking the same "Are you my mummy?" question before settling down at dusk with its 'mother' in the nest again...... most unusual......