George Claassen

Get rid of the aliens!

2005-08-26 09:30

South Africa's endemic species are under serious threat from invasive and exotic species. No, this is not really newsworthy. As far back as 1989 the Department of the Environment declared war on these plant and animal species that are endangering indigenous species to the brink of extinction.

But when I recently visited Northwest Province and Limpopo, the relentless progress of one of the most iniquitous bird species making inroads into the country areas north of the Vaal River, was unmistakable.

The Indian Myna (Acridotheres tristis) has recently been included as one of three bird species on the International Conservation Union's list of the 100 most invasive species.

Two years ago environmental protection experts of the Western Cape declared war on the invasive house crow (Corvus splendens) by an active programme of extermination of the species.

It was first described by the ornithologist Vieillot in Bengal in 1817 and was first observed on South African soil in 1975 when it appeared in Durban.

The European starling

Another invasive bird species that is destroying endemic species of the country, is the European starling (Sturnus vulgaris), also known as the Rhodes starling because it was introduced by Cecil John Rhodes to the Cape in 1899.

It has quickly developed into a plague spreading to the Namibian and Natal coasts, reaching according to Roberts' Birds of South Africa Clanwilliam in 1950, Port Elizabeth in 1955, King William's Town in 1961 and East London in 1966.

Two months ago the Johannesburg journalist Neels Jackson of Beeld reported that this bird has now now also been observed in Sasolburg, just south of the Vaal River, more than a 1 000km from Cape Town.

Why this serious concern about invasive species? Isn't it a matter of the survival of the strongest in nature, a matter of natural selection of species to come out on top of the chain of the living?

The twice winner of the Pulitzer Prize and one of the world's leading biological diversity experts, Edward O Wilson of Harvard University, writes in The Diversity of Life (Penguin) "the causes of extinction, which are virtually all due to human activity, can be ranked from the top down as follows: habitat destruction or degradation, the spread of exotic (nonnative) species, pollution, over-harvesting, and disease."

Invasive plants

He points out that by the late 1990's 11% of free-living plant species in the United States were invasive. The figure for Ontario was 28%, for the British Isles 43%, and for Hawaii 44%.

In South Africa the Working for Water programme has had good results in containing the spread of invasive plant species. According to this programme's website, biological control research has been practised for more than 85 years, and more than 103 biological control agents have been released against 46 weed species.

Unfortunately little has been done to start a similar programme to address the problem of invasive bird and fish species.

In 2003 the municipality of Newcastle in KwaZulu-Natal decided that they could no longer tolerate the damage the Indian myna was wreaking on indigenous species.

It started an extermination programme, an example of proactive environmental protection that should be followed by all other municipalities around the country. And it should include the European starling and the house crow.

Yes, bleeding-heart animal lovers such as the group who tried to prevent the invasive tahrs being removed from Table Mountain where they were destroying the fynbos and other indigenous species, would complain.

But, as Wilson emphasises, "the costs of immigrants far outweigh the rather narrow and meagre benefits they bring".

  • George Claassen is the science editor of Die Burger, Cape Town's largest circulation daily newspaper.

    Send your comments to George or discuss this column now in our debating forum.

    Disclaimer: News24 encourages freedom of speech and the expression of diverse views. The views of columnists published on News24 are therefore their own and do not necessarily represent the views of News24.

    Disclaimer: News24 encourages freedom of speech and the expression of diverse views. The views of columnists published on News24 are therefore their own and do not necessarily represent the views of News24.

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