“We are all familiar with adult White-breasted Waterhens (Amaurornis phoenicurus phoenicurus) and the small black chicks they have. I saw this bird, adult sized but with plumage that appeared to be moulting (above left). I have not seen White-breasted Waterhens moult in all my years of watching.
“I considered whether this was a ‘skin’ disease where it had lost feathers and there were re-growth, but the beak looks immature (posting an adult for comparison in – above right). So I suspect this is an immature moulting into an adult.
“…for comparison, the plumage of a younger immature bird taken in October 2008 (left).
“Supports the idea that the bird is moulting into its slaty grey upperparts.
Dato’ Dr Amar-Singh HSS
Limestone Hills Outskirts of Ipoh City, Malaysia
10th October 2010
It seems very unusual. The bill colour and the colour of the uppertail coverts seems to suggest immature plumage. However, it is not normal for birds to shed ALL the flight feathers at the same time! The picture of the younger immature bird shows the browner juvenile primaries.
I do not know the moult strategy used by this species but it would normally moult the feathers from the outside inwards (or in the reverse direction), and only two or three feathers should be in growth at any moment in time. I wonder, could it have been an escaped captive bird, whose wings had been clipped?
That looked like a clipped wing to me. Very positive suggestion as we all know the avian species do not moult flight feathers all at the same time.