Pachyderm overpopulation

South African elephants may get a birth-control vaccine to reduce herd size.

By Jack Boulware
September 25, 2000 11:08PM (UTC)
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If there is a downside to the protection of endangered species, it's the potential for overpopulation. And when the species in question is one of the world's largest animals, things can get a bit touchy. A national park in Africa has been set up to protect elephants from natural predators and allow them to reach their natural life span of about 60 years. But the project has resulted in a lot of elephants.

Kruger National Park lies along South Africa's border with Mozambique. In an area roughly the size of Israel, Kruger can support a maximum of 8,000 elephants without disrupting the populations of other species. But Kruger has a problem. Its pachyderm population is growing by 7 to 8 percent a year, and each animal eats up to 600 pounds of food per day. The park has tried to give away its surplus elephants, but there's not enough demand, so it's now faced with killing hundreds of the beasts each year. If the population isn't controlled, members of the species will tromp and eat their way through the park, turning it into a wasteland of dead trees, much like areas of Botswana and Zimbabwe.


The answer to this problem, say scientists in a recent issue of Nature, is an elephant contraceptive. And no, they're not talking about a diaphragm the size of a Honda Civic or a delicately positioned suppository. The solution found by a group of U.S.-South African researchers is a vaccine that affects an elephant's immune system. Certain antibodies are produced, which then lock onto proteins on the surface of the elephant egg, preventing sperm from fertilizing it. In trial runs, 31 females were injected with the vaccine, and only 11 became pregnant.

If introduced, the method would provide a welcome humane alternative to thinning the herds. "Elephants are intelligent and empathetic mammals, and culling is a last resort in controlling their numbers," said the scientists.

Several years ago, a group of German scientists attempted a similar technique, feeding estrogen to female elephants. The results ended in disaster when two cows remained permanently in heat, and attracted a never-ending stream of horny bulls. In the ensuing chaos, two calves were trampled to death.


The U.S.-South African team asserts this won't happen with their new vaccine, and says its effects are easily reversible.

Although this research sounds promising, African groups argue that contraception is unnatural and selfish, and would deprive locals of the opportunity to harvest ivory, hides and meat from the surplus elephants.

But there is another option they might try that has been found to work wonders as birth control in human beings -- give the elephants alcohol, tobacco and cable TV.

Jack Boulware

Jack Boulware is a writer in San Francisco and author of "San Francisco Bizarro" and "Sex American Style."

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