NG stock photo of male mallard duck (Anas platyrhynchos) by Bates Littlehales
By Leon Marshall
Johannesburg–Some people get very upset whenever there is talk of exterminating invasive alien bird species, even if they pose a threat to a country’s own birds. In South Africa, the effort to eradicate non-native birds has even been compared to the kind of xenophobia that is supposed to be behind the sporadic outbreaks of violence against human migrants from other African countries in townships around the country.
So when thoughts turn to taking action against offending feathered aliens, the conservationists know they have to go about it with the utmost circumspection so as not to risk turning broad public opinion against them.
The latest alien 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 [that is, playas or dry lake beds], especially in and around cities and towns, but also in water systems further afield.
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.
Over the past two years a campaign has been run to exterminate the patently less appealing house crow, and even that initially met with some resistance. The species was introduced from India and became a menace in and around the coastal cities of South Africa.
Being vociferous breeders and feeding on the eggs and chicks of other birds, crows drove indigenous species from entire suburbs. When they started attacking school children to get at their food, public opinion turned against them. About 10,000 crows were counted in trees surrounding a school in one of Cape Town’s poorer areas.
Through a selective baiting project using chemicals that would not cause secondary death to animals eating the carcasses of dead birds, the crows have been practically wiped out in the major harbor city of Durban, and are on their way to being eradicated in Cape Town.
The situation is less stark with mallards. 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 throughout the sub-continent.
There have even been reports of the European interlopers interbreeding with the ostensibly assertive Egyptian goose (Alopochen aegyptiacus), an abundant indigenous species that is the bane of golf courses, where they litter greens with their droppings.
Louise Stafford, who heads up Cape Town’s invasive alien species program, co-ordinates a national task team to look into the mallard problem. Well aware of public sensitivities, she chooses her words carefully, noting that there is no firm decision yet as to what to do about the ducks, and that the likely course will be not to “exterminate” them but rather to try to “control” them.
She does point out, though, that one of South Africa’s most eminent ornithologists, Dr Phil Hockey, already warned as far back as the early 1980s about the mallard threat. Hockey is the lead editor of the authoritative seventh edition of Roberts Birds of Southern Africa, published under the auspices of the University of Cape Town’s prestigious Percy FitzPatrick Institute of African Ornithology.
BirdLife South Africa is an integral part of the mallard project. Hanneline Smit, its conservation manager, will raise the issue of what to do about the ducks when she meets with BirdLife International staff in London this month.
She says that with the International Invasive Bird Conference due to be held in Cape Town next, Mark Anderson, executive director of BirdLife South Africa, has proposed a full workshop to explore the issue further. The aim is to get all interested parties, including officials from central government and the provinces, together to discuss the issue and work out a plan of action.
Stafford says 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.
As a first step, it has therefore been decided to institute a strictly controlled hybrid-breeding program to see exactly what the first- and second-generation hybrids look like. This would make it easier to target them in the open if and when a control program is launched.
“There certainly is going to be no big bang. We want people to understand and to support us. I believe it is even now still possible to buy and sell mallards in South Africa. It is just one of the many aspects [of the problem that] we’ll need to look at,” she says.
A “special watch” feature called Operation Mallard Alert (OMA) has been established on the South African Bird Atlas Project 2 (SABAP2) website to help determine how many mallards there are and how big the problem is with the assistance of citizen mappers.
The atlas project is run by the University of Cape Town’s Animal Demography Unit. Professor Les Underhill with the research group says the “special watch” feature provides a tool whereby data on mallards can be incorporated into a separate database and made available to project coordinators.
Nat Geo News Watch contributing editor Leon Marshall is an environmental writer in South Africa. A leading political journalist and executive editor for Africa’s largest newspaper group for years, he has won numerous awards, including a 2004 Reuters-IUCN Media Award for Excellence in Environmental Reporting. Leon has covered climate change from a global and African perspective, having attended conferences on the issue in many parts of the world. He has written extensively on the ambitious transfrontier-parks program of the sub-continent and is now writing a book on the subject.