The latest feathered alien in South Africa identified as a threat is the mallard duck (Anas platyrhynchos), a European species that got brought into South Africa over the past few decades and which is now a common sight on lakes and pans..
The mallard happens to be a striking bird, particularly the male, which has a metallic-green head and neck, a yellow bill, and a purplish-brown chest. The female is uniformly brown-streaked, but, though duller in appearance, it is hardly less graceful. It is their beauty that caused many people to import the birds to adorn their garden ponds in the first place, and it is this same attractiveness that is going to make any program to control their spread decidedly difficult. They interbreed with indigenous duck species, particularly the yellow-billed duck (Anas undulata) a ubiquitous waterfowl occurring practically throughout South Africa, and the African black duck (Anas sparsa), an even more widespread but less abundant bird.
One of the problems is that it is not entirely clear what the offspring of the mallards and the indigenous ducks look like. It does appear, though, that the hybrids are fertile, thus compounding the danger. You may actually spot a Mallard in this area.
Ducks normally nest near water on the ground, but there is always an exception………..