The introduction of six bull elephants seems to have sorted out the `aberrant behaviour’ of the young males in Pilanesberg, writes Barbara Ludman
It was the sort of scene certain to delight visitors lucky enough to come upon it: a young bull elephant and two much younger males browsing peacefully together in the sparse bushveld, just a metre from the road.
But it was no ordinary encounter at Pilanesberg National Park this week, nor was it necessarily as peaceful as it seemed. As the big bull crossed the sand road, one could see his radio collar; and as one of the young elephants followed, one could see a wound just above his tail.
For Pilanesberg, that’s good news. It means the experiment may be working.
Exactly one year ago, the same bull was captured in the Kruger Park and, with five other adult bulls, released in the Pilanesberg reserve in a desperate effort to sort out young elephants who had been – as the biologists put it – “exhibiting aberrant behaviour”.
The behaviour was not only aberrant; it was tragic. Young males were going into the sexual frenzy of musth a good 10 or 15 years too early. Musth is a heightened state of aggression associated with reproduction in male elephants. Unable to deal adequately with his raging hormones, in 1993 one young elephant killed both a tourist and a professional hunter sent in after him. A year later, young male elephants began killing rhinos.
It’s a basic South African story, shot through with sex and violence. And it begins with the way elephants were culled 20 years ago; adults in a herd destroyed, but the youngsters saved, if possible, and translocated to reserves looking to start elephant populations.
The first batch of Pilanesberg elephants were the young survivors of culls at Kruger: 18 orphans between the ages of four to six were released in Pilanesberg in 1980. Two years later, in an effort to calm them down – aberrant behaviour was already a problem – two adult females were released into the park, and a year later, another lot of infant orphans joined the herds. That system continued until 1993, when Pilanesberg took its last consignment of infants who had survived a cull.
By then it was obvious there was going to be trouble. The males among the first batch of orphans were now going into musth, much too early.
“Generally elephants only go into musth from the age of 35 or 40,” says Gus van Dyk, field ecologist at Pilanesberg. “There were 16 bulls now in their 20s. We needed older bulls to put the young bulls in their place.”
The suppression of reproduction through behavioural dominance is a process documented in other animals, like lions and porcupines, but never before in elephants. “The mechanism isn’t well understood,” he says. But whether the process is dependent on pheromones or on social structure, in some species only dominant animals get to reproduce.
In 1994, 20 white rhinos were found dead at Pilanesberg, most of them killed in a two-month period. Two years later, another 20 were killed. The wounds were consistent with elephant attacks. In 1997, a young male was caught killing a white rhino.
Young male elephants had been associating with rhinos at Pilanesberg for years, possibly because the elephants had no idea that rhinos were a separate species. As the elephants went into musth, some of them were turning homicidal. Some intervention was needed, and quickly.
The decision to introduce older males had input from many sources, including elephant behaviourist Joyce Poole, the Kenya-based expert on musth; Robert Slotow at the School of Life and Environmental Science at the University of Natal in Durban (UND); the North West Parks and Tourism Board, which runs Pilanesberg; and biologists based at the reserve.
Early last year, six adult males between the ages of 25 and 35 were captured, two at a time, at Kruger, off-loaded into a boma at Pilanesberg, left for three days to familiarise themselves with the concept of an electric fence, then released into the reserve.
Research assistants attached to UND and the parks board report that by now each of the six bulls has encountered every other elephant in the park. And the rhino killings have stopped.
The biologists are being cautious. The experiment “seems to be working within the parameters”, says Slotow. “There have been no negative results up to now. But we need to see whether it remains at that level.”
What they can say, however, is that the tendency for young males to go into musth for several weeks at a time has changed dramatically.
“There has been a total turnaround of the known musth conditions,” says Van Dyk. “The musth period has been disrupted. That’s what we wanted – to shorten the period and delay the onset. But it remains to be seen whether the manipulation of musth will be sufficient to stop the killing of rhinos.”
There have been other useful spin-offs of the programme – like the identification of the wounds that have been appearing on young male elephants since the older bulls arrived. Poole saw the same wounds at Amboseli, and assumed they came from the spears of Maasai warriors – but that’s obviously not the explanation at Pilanesberg. “A possible scenario,” says Slotow, “is that it’s the older males disciplining the younger ones.”
And in order to see how the programme is working, UND research assistants have embarked on a massive individual identification programme. The older bulls have all been identified, largely by markings on their ears. As younger ones grow, their ears also will take on defining characteristics, and they will be entered into the database.
“The only population studied to this extent is the one at Amboseli,” says Slotow. With fewer than 100 elephants at Pilanesberg, and a highly restricted area, “it’s telling us a lot about how to manage elephants in small reserves, as in South Africa”.
Once elephants are identified, they can tell which ones are browsing together, whether they stay together or move on; whether the two 14- year-olds are going to stay with the big bull, find another role model the next day, move on together or separate.
Most important, however, are the implications of the study for translocations. “In future,” Slotow says, “we must translocate specific individuals, with knowledge of their relative position in the social system.”
ENDS