The last victims of Robben Island

It may be more than a decade since South Africa's first free elections, but apartheid is still claiming victims. This time, however, it is penguins that are being killed - by the descendants of pet cats kept by warders on notorious Robben Island.

At least 70 wild cats are freely roaming the island, where Nelson Mandela spent most of his 27 years of captivity, and decimating wildlife. Now a sharp-shooter has been hired to pick them off, causing an outcry from animal lovers.

The windswept dot in the ocean - 12 kilometres offshore from Cape Town, and a place of incarceration for more than 400 years - is now a wildlife reserve. More than 130 bird species - including 7,000 breeding pairs of African penguins - throng the island that was first used to hold prisoners in the 17th century.

But a meeting of experts decided this month that feral cats descended from warders' pets left behind when Mr Mandela and his colleagues were freed are "having a devastating effect on most of the endangered birds on the island".

And Professor Les Underhill, the head of the Avian Demography Unit at the University of Cape Town , claims that the cats are severely endangering one of the islands rarest birds, the protected African Black Oystercatcher.

Five years ago, he pointed out, almost 60 oystercatcher chicks grew to maturity, but last year just three escaped the feline menu. The cats, he adds, are eating large numbers of penguin chicks - while other rare birds have given up on the island altogether and are breeding elsewhere.

"It is serious stuff," said Professor Underhill. "Cats don't belong on offshore islands where there are breeding birds."

But the employment of a sharpshooter has infuriated the local branch of the country's Society for the Prevention of Cruelty to Animals. It has argued that this is violating an agreement with the island authorities that allows the society to trap the animals, sterilise them and return them to the island.

The authorities retort that sterilised cats also kill birds and point out that the society's attempts to trap them have failed; a blitz earlier this year netted only eight of the animals.

Alan Perrins, the chief executive officer of its Cape of Good Hope branch, admits the lack of success - but blames the penguins for the fiasco. He suspects that the birds had set off the traps laid for the cats by snaffling the bait of pilchards and chicken.

Anyway, he says, the former pets may not be the real new villains of Robben Island, pleading for the authorities to be "a bit more open-minded".

For example, he adds, mice three times the normal size had been found to be decimating seabirds on another island nearby. And he urges that a "radical theory" - that rabbits "running around like packs of rats" might have turned carnivore - should not be dismissed, though he could provide no evidence to support it. Other potential villains on his list include the black mole snake, which eats eggs and young birds, and the 1,000 or so tourists who land to visit the former prison each day.

But Professor Underhill and the authorities are unmoved. They want to get the shooting over before the winter rains arrive, allowing vegetation to grow and give the animals cover.