CAPE TOWN, South Africa (AP) _ The wind-swept island where former President Nelson Mandela spent most of his 27 years in jail is prized nearly as much for its teeming wildlife as its historical significance.

Robben Island, off the coast of Cape Town, is home to about 132 bird species, including the protected black oyster catcher and about 7,000 breeding pairs of African penguins.

Now the rare birds are being killed, and the island's historic museum is fighting the Society for the Prevention of Cruelty to Animals over who is to blame. Among the suspects: wild cats, giant mice and, possibly, flesh-eating rabbits.

Robben Island authorities maintain that dozens of feral cats left behind by prison warders and their families are disrupting the delicate balance of nature. On April 11, a meeting of experts agreed to hire a sharp shooter to kill the roughly 70 cats, saying they were ``having a devastating effect on most of the endangered birds'' on the island.

``It's serious stuff,'' said Les Underhill, head of the University of Cape Town's avian demography unit, who works closely with Robben Island environmental officials. ``Cats don't belong on offshore islands where there are breeding birds.''

The SPCA objected, saying the cat kill would violate an agreement to allow the society to trap the cats, sterilize them and return a small number to the island to control rats.

The SPCA mounted cat-catching patrols earlier this year but only managed to trap eight, according to Allan Perrins, chief executive officer of the society's Cape of Good Hope branch. He suspected that penguins had set off the traps by eating the bait of pilchards, a small fish, and raw chicken.

And, the society suggested, maybe cats were not to blame at all.

``All the focus at the moment is honed in on cats being the primary suspect,'' Perrins told The Associated Press. ``We would like to make a plea to be a bit more open-minded.''

He cited the example of a nearby island where it was found that mice three times the size of an average house mouse were decimating seabirds. And, Perrins said, authorities should not dismiss the ``radical theory'' that the thousands of rabbits running wild over the island might be involved.

Perrins stressed there was no evidence of rabbits eating eggs and young birds. But he said one of his inspectors spoke of ``rabbits running around like packs of rats'' on the island. He also cited the tendency of rabbits kept in a confined environment and deprived of food to eat their young.

Other suspects include the black mole snake, which is fond of eggs and young sea birds, not to mention the 1,000-odd tourists who visit the former prison each day, Perrins said.

Bird expert Underhill slammed the SPCA for drawing rodents and rabbits into the plot.

``It is such a stupid idea that it is embarrassing,'' said Underhill. ``It is not the rabbits who are responsible. It's the cats.''

He said that during a previous roundup of cats, in 1999, analyses of stomach contents revealed remains of birds and rare chameleons.

After the 1999 eradication program, bird colonies _ including swift terns and Hartlaub's gulls _ flourished. During the 2001-2002 breeding season, 59 endangered African Black Oystercatcher chicks reached maturity, according to the Robben Island museum.

Bird expert Underhill said that last year just three chicks survived, and observers found the telltale signs of strewn-about identification-tag rings and feathers, indicating kills by cats.

Substantial numbers of African penguin chicks also are being devoured, Underhill said. And colonies of gulls and other birds that would normally breed on the island are being displaced to less favorable coastal sites, including an oil refinery.

But cats, rabbits and rodents are not the only pests on Robben Island. Seals around the island are on the increase and beginning to attack the penguins. And there are sizable populations of fallow deer, springboks, ostriches and other animals that are not indigenous.

Robben Island, which was used between beginning in the 17th century as a leper colony, then a military base and a prison, was declared a U.N. World Heritage Site in 1999 for representing ``the triumph of the human spirit, of freedom and of democracy over oppression.''

In order to keep its prized status, it has to meet a number of conditions, including the control of alien species.