Mallard moult

Mallards: female in foreground, male in breeding plumage in back

Male Mallard in eclipse plumage; his yellow bill reveals his sex



With a gazillion Mallards around the area, and each one of them moulting twice a year, one might expect to see them undergo this loss and regrowth of feathers with considerable frequency. Yet, I cannot recall having seen a Mallard in the process of moulting prior to Thursday.

When the female Mallard moults, she replaces her worn feathers with new ones having the same pattern. The transition is inconspicuous.

The male, however, switches between his breeding plumage and his eclipse plumage (during which time, he looks like a female). It is a big shift and during the transition, he should look distinctly anomalous.

So, why is this odd duck rarely seen?

Answer: He hides.

When a male Mallard moults, he loses all of his flight feathers simultaneously. His flightless state leaves him particularly vulnerable to predators. So just prior to moulting, he goes into seclusion, often hiding in a marsh. He is loath to reappear until in his breeding finery.

The odd-looking head and neck of Thursday’s male Mallard (foreground) reveals him to be only part way through the moult into breeding plumage. The colourful water results from the reflection of the fall foliage beyond them.

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6 Responses to Mallard moult

  1. Susi says:

    Beautiful photos! Just curious, any idea how long the male mallard remains in a flightless state? Does the female mallard also transition into a flightless state?

    • Alistair says:

      Susi, many birds replace their feathers a few at a time so as to avoid becoming flightless. The Mallards (both sexes) replace all flight feathers at once in a process that lasts up to two weeks. In the above picture, it seems that the replacement of the flight feathers has been completed, but those on the neck and head are still in transition.

  2. carol pettigrew says:

    Allistair, The female also moults ALL her flight feathers in August. It is not just the male. She also hides. Beaks has female ducks nearly every year going thru the summer moult..

  3. Bill Baerg says:

    The question that keeps coming back to haunt me is ” why is this particular male about 3 MONTHS late with his molt” ??? Is he the result of non migratory local ducks breeding off season ? I do come back to my first position; that this is a late hatch single egg and it’s Mom that is beside him.

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