Conservation Issues in the Republic of South Africa

Invasive species pose a threat to nearly every ecosystem on the planet. In South Africa, the situation is no different. South Africa’s environmental agencies have identified hundreds of invasive species that all have some negative effect on native individuals or populations. To expound upon each would require far too much time. Instead, I will focus on three bird species: the Indian Myna (Acridotheres tristis), the house crow (Corvus splendens), and the mallard duck (Anas platyrhynchos).

Why are birds among the most prevalent clades of all invasives to South Africa? Probably the most significant factor in this phenomenon is the fact that South Africa’s bird population is both large and highly diverse. There are hundreds upon hundreds of bird species in South Africa and most of these species are thriving. South Africa’s landscape provides highly diverse habitat types. This fact, combined with the diverse food, water, and habitat requirements each species may have relative to another, is the key to the problem of invasive bird species to South Africa. A wide variety of needs are met by South African ecosystems—for native and non-native birds alike.

The Indian Myna is a medium sized brown bird that lives in large groups. They are omnivores. Their threat to biodiversity is high because they are aggressive and can live in a number of different habitat types. The Indian Myna was originally introduced in Hawaii to control the insects destroying sugarcane crops1. However, it drove out native species by taking over their nests. They also compete for resources and tend to beat out native species if the Myna population is large. Once natives are removed from their nests their populations decline greatly. Mynas are known to disperse seeds of an invasive plant, Lantana camara1. Finally, Indian Mynas have no natural predators in South Africa, which makes them remarkably difficult to control3.

The house crow, which is closely related to the common crow found in the United States, originated in India. Its movement is generally correlated with human movement; its populations tend to cluster around cities and towns. The house crow will eat the eggs of native birds, preventing completion of the reproductive cycle in that case. It has also been known to eat nestlings and small mammals. Reproductive inhibition is the crow’s greatest threat to native bird species and biodiversity. The house crow is also a nuisance to humans in a given area as it will eat vegetable gardens and even attack pets. Finally, the house crow is a known carrier of the pathogens that cause such diseases as cholera, typhoid, and dysentery2.

The mallard duck is a third invasive bird species recognized by South African wildlife agencies. The largest problem posed by the mallard duck is that it is able to breed with forty-five indigenous species of ducks including the yellow-billed and African black ducks3. A similar phenomenon is seen in the mating of donkeys and horses, which produces infertile mules. However, the offspring of mallard ducks and these two native duck species are fertile. This means that, after several generations of interbreeding, mallard ducks could completely erase