An eclipsed duck

Ducks are peculiar in that they moult all their flight feathers at once. This means that for about a month, they can't fly and are vulnerable to predators.

To provide some protection, particularly for the brightly-coloured males, the moult starts with their bright body feathers. These are replaced by dowdy brown ones, making them look much like females. This is a male Eider duck Somateria mollissima in his eclipse outfit. In his breeding attire he is, as you can see,  a very striking duck indeed.

Once the flight feathers have regrown, the birds moult once more, and by October the full colours are back and the males are looking resplendent once gain.