Zandvlei Trust

Mallard Duck – The True Ugly Duckling

(Extract article from the volume 2009/1 Newsletter)

Beware the Gang Rapist: although this duck is one of the more attractive birds frequenting the waterways of Zandvlei and the Marina it is certainly one of the less desirable species that we wish to see on our waterways. This is because, despite its good looks, it is a declared invasive alien species.

It is a declared alien because it cross-breeds freely with our indigenous Yellow-billed Duck and, what is worse, hybrids of Mallards and Yellow-billed Duck are fertile and can produce more hybrid offspring. So the white duck and most of the multi-coloured (brownish) are offspring of the Mallard. If these hybrids remain the survival of our indigenous Yellow-billed Duck, as a true species, is threatened.

For us common folk a species is one of the basic units of biological classification. A species is often defined as ‘a group of organisms capable of interbreeding and producing fertile offspring’.

The scientific name of a Mallard Duck is Anas platyrhynchos. Anas meaning duck in Latin and platys (broad or flat) and rhyncos (beak) in Greek) and a Yellow-bill is Anas undulata. This means that they are classified as separate species but do belong to the same genus or Duck family.

Photograph by Louise Stafford                               Photograph by Ann Koeslag  

Male Mallard hybrid                              Yellowbilled Duck

The Mallard Duck originates from the Northern Hemisphere where it was domesticated many years ago. It is kept as an ornamental bird and is used for its feathers, meat and eggs. It has been introduced to many countries around the world and is causing severe genetic pollution in countries such as South Africa, New Zealand, Australia, Mexico, Hawaii and parts of America. It is a relatively noisy bird and it is responsible for the characteristic ‘quack’ that is heard in the Marina.

Perhaps its only redeeming feature is that the male Mallard is very colourful and has a metallic green head with a white ring around the neck during the breeding season. The female is a drab brown and can hardly be recognized as being of the same species. In late summer when they are not breeding the males lose their breeding plumage and resemble the females. But, don’t judge a book by its cover.

The Mallard male is known as a ‘Gang Rapist’. Researchers, however, refer to this phenomenon as rape flight. This very aggressive strategy can often be seen in the waterways of the Marina when a bunch of drakes who might feel ‘left out’ gang up on an isolated female duck, chasing, pestering and pecking at her until she weakens and gives up. They then take turns in raping the female.

Mallards and their hybrids compete with indigenous birds for resources such as food, nesting and roosting sites. There are cases where Mallard males kill offspring of other waterfowl by frequently attacking and drowning them.

The groups of multi-coloured ducklings that are so sweet and charming in summer are usually the result of a Mallard drake breeding with one of the Yellow-billed Duck females. These ducklings are usually a result of rape flight and unfortunately they have to be eliminated if we want to maintain the genetic integrity of our indigenous Yellow-billed Duck. One of the ways in which we can eliminate them is by not feeding them. Feeding them creates an artificial source of food for them to survive on!

Another way of controlling them is through culling. Shortly this may well have to happen; so, dear readers, if you are guilty of feeding them, please stop, now.

Peter Kruger


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