Disappearing Ducks

Where have all the male ducks gone? As you look around the Nature Reserve you may have noticed that all of the brightly coloured drakes seem to have disappeared. The male mallard with its iridescent green head, purple brown breast and grey body, or the contrasting black and white of the male tufted duck can simply no longer be seen. So where have they all gone? You may be surprised to know that they haven’t actually gone anywhere they are just undergoing their post breeding moult known as ‘eclipse’.

Feathers are extremely important to birds. They are vital for flight, provide insulation and have evolved into a massive array of colours and patterns to be used in courtship and sexual selection. Bird’s feathers often wear out during the year through flying, exposure to the sun, rubbing against other feathers and parasites such as lice and mites. Feathers therefore need to be regularly replaced and moulting is the process of shedding and regrowing them. Unlike most other birds’ ducks, geese and swans lose all of their flight feathers at once leaving them flightless for a few weeks.

The moult process in mallards starts by shedding the bright coloured body feathers which are replaced with the dull brown feathers seen in the ‘eclipse plumage’. This makes the males look a lot like the females and provides them with some camouflage during their vulnerable flightless period. After the flight feathers have regrown, the birds go through a second moult phase, and by October the male’s full colours will have returned.