But where have the mallard males gone?
It's September and the male mallards seem to have abandoned Lake Geneva. But think again! The males are still there, but they are taking on a plumage that resembles that of the females; in fact, they are switching to the internuptial plumage, also known as the eclipse plumage.
Every year in winter, at the start of the breeding season for Anatidae (aquatic birds with robust legs and sexual dimorphism, such as the Mallard, the Red-crested Pochard, the Goosander...), the birds change plumage. Males go from a dull autumn plumage to a plumage that is generally more colourful; it is the males that do the courting, and they rely on their beautiful plumage to attract a mate (homosexual behaviour in mallards has been widely documented, particularly in males). But it's not just for purely aesthetic reasons that the most colourful males are the most prized for reproduction; the pigments involved in feather colouring are also important for immune defence. A coloured male therefore represents a healthy individual, which is inevitably more attractive when it comes to producing offspring! Once the breeding season is over, males revert to duller colours, making them more discreet in the face of predators. This also reduces aggression between males, who are no longer competing with each other.
That's why, from August onwards, the bright green flashes of mallard heads are becoming increasingly rare on the lake!
Females, on the other hand, retain their dull plumage throughout the year; like the males, this enables them to camouflage themselves better, which is particularly important during the nesting period, as they cannot move too far from the nest and therefore have very limited mobility. Despite their uniform colouring throughout the year, females also moult, renewing their plumage, which wears naturally over time.
This moult can be either gradual or abrupt. In the mallard, for example, moulting takes place gradually on the body and wings. The remiges - remember, these are the feathers that enable flight - fall at the same time, leaving the ducks unable to fly for a period of around three weeks. Note that the feathers are renewed in a mirror image between the right and left sides of the bird, to avoid creating imbalance.
So how can you tell the male from the female during this period? The male's beak is greenish-yellow, while the female's is greyish-orange.
So don't worry... the male mallards won't abandon us!
Photo credit: Marjolaine Rion
