YOUNG, SINGLE AND OUT OF CONTROL

The trouble first surfaced about three years ago. Rangers in Pilanesberg National Park, in northwestern South Africa, began to notice that white rhinos were being killed at the rate of about one a month. Then the same phenomenon started happening at Hluhluwe-Umfolozi Park, in the southeastern section of the country. Poachers looking for precious horns are the usual suspects when rhinos turn up dead. But not this time. These animals were left intact, horns and all. Their wounds, moreover, had been caused not by gunshots but by long, sharp objects with some mass to them.

The mystery was soon solved: the rhinos had been murdered, all right, but the perpetrators were not poachers but pachyderms--young, aggressive bull elephants that did in the rhinos by knocking them over, kneeling on them and goring them.

What drives the elephants to do it is not clear. Game wardens and animal-behavior experts have a theory, however, and while they stress that it is speculative, the idea is compelling. The elephants may be depraved, the experts say, because as children they were deprived. The troublemakers are apparently all orphans, taken as calves from their slaughtered parents during culling operations in the huge Kruger National Park and relocated to establish elephant populations in parks and private reserves throughout the country.

One positive result of the operation was that it helped preserve a threatened species. But because elephants in the wild live in tight-knit groups, the relocation was also a major experiment in social engineering--and like so many such experiments, it has had unexpected consequences. Since 1978, almost 1,500 orphan calves, 600 of them males, have been moved to unfamiliar locations and raised with no exposure to adult elephants or the hierarchical social structure that defines elephant life.

The long-term effect of this isolation appears to be a generation of juvenile delinquents. "The whole thing has much to do with the setup of elephant society," says zoologist Marian Garai, a Swiss-born South African who has been studying the relocation. Under normal circumstances, she says, a dominant older male elephant is around to keep young bulls in line. For the newly arrived youngsters, however, no such role models were provided, and Garai believes this may have had a profound effect on the elephants' psychology.

The result may be even more pronounced during the period known as "musth," a time when male elephants' testosterone levels shoot up. Elephants often become aggressive during musth, but in the wild, older bulls usually keep the young ones in line. Not only are the orphan bulls going into musth without chaperones, but their musths seem to start earlier and last longer. The condition usually begins at age 30, but at Pilanesberg some 20-year-old elephants are going into a musth that lasts not the usual few days but as long as three months.

Why do these elephants pick on the rhinos? Evidently, because they're there. At least one human was killed by a rogue bull last year, but for an elephant looking to make trouble, a small, relatively helpless rhino is an easier target. Garai has often seen a young elephant grab a stick in its trunk and throw it at a rhino--seemingly playful behavior that in an unbalanced animal could easily turn violent. "Elephants are complex and intelligent creatures," she observes. "They aren't immune to stress." She suspects that other game parks with populations of orphan elephants may soon develop similar problems.

Park rangers are prescribing a little adult supervision for the bad-boy elephants. Indeed, when two adult female circus elephants were returned to Pilanesberg in 1979, shortly after the first orphans arrived, the nervous youngsters quickly settled down. Now officials hope something like that will work on rhino-bashing bulls. Early next year, a few 40-year-old bull elephants will be moved to Pilanesberg to help calm things down. Meanwhile, authorities are trying to get to the root of the problem. Two years ago, Kruger Park stopped its elephant-culling program and began moving entire families of elephants to their new homes.

It will be some time before the effects of these efforts are known. Until then, the white rhinos of South Africa had better watch their backs.