The duck that changes coat
The mallard, known in Malta as kuluvert, is a wild duck found in the Americas, Europe, Asia and North Africa. It has also been introduced in Australia and New Zealand.
Mallards visit the Maltese Islands in autumn and winter. One or two can regularly be seen at the Għadira Nature Reserve where they sometimes join a colony of feral mallards that resides there.
The male mallard has two different plumages. In the breeding season it has a conspicuous shiny green head, brown chest and grey body, but during the rest of the year it sports speckled brown feathers similar to those of females.
Most ducks have the same moulting pattern and outside the breeding pattern superficially look very similar. Often what distinguishes one species of duck from another is a patch of coloured feathers on the wing, known as a speculum.
The male mallard’s vivid colours help it to attract females during courtship, but bright colours are also conspicuous to predators so, as soon as the eggs hatch, the male moults into the less conspicuous non-breeding plumage.
Moulting is an important yet dangerous process. In the initial phase, the duck’s feathers start to fall off and new ones grow in their place.
New feathers are full of blood and grow very fast, but they are heavy. When a feather is fully grown, the blood supply is closed off and the feathers become hollow and light.
During the post-breeding moult, which takes place in late summer, the feathers are lost and replaced in a short period of time. This results in many feathers being lost at the same time and the ducks becoming flightless for up to two weeks, which makes them very vulnerable to various predators.