Backstory: How to control a herd of wild elephants

As the sun dips below the ridgeline of African scrub and the shadows finish their nightly colonization of the rocky dirt road, Audrey Delsink slows her rumbling, open-air truck and peers into the brush. This, she senses, is where they'll come out. She switches off the ignition.

"Do you hear that?" she whispers. Snapping branches and crunching shrubs, the sounds of something very big moving just behind the veil of dusk. Within seconds, the tusks of a bull elephant glint in the moonlight. The rest of him appears slowly, following the ivory; his shoulders more than 8 feet high, his weight more than 5,000 pounds. The tip of his trunk moves in little circles, smelling. He's close enough to crush the vehicle with a well-placed pachyderm stride. Ms. Delsink, unconcerned, drapes a slender, tanned arm over the steering wheel.

"This is a young bull named Flap," she says, as if introducing an acquaintance at a cocktail party. "He's only about 18 ... but he's got really long tusks for his size." Flap eyes the truck and Delsink. Then, satisfied, he ambles back into the darkness.

Once, when she was more than a little phobic of elephants, she'd have been terrified, Delsink says, but now the wildlife researcher knows Flap, and the rest of the 72 elephants in the Makalali Game Reserve. She knows he wouldn't take out a vehicle just for the heck of it, because that's not what elephants do. Not normal elephants, at least.

Delsink spends hours alone in the back of her pickup watching elephants - recording every interaction, step, and chew - to determine if the Makalali herds are, in fact, normal. For five years she has watched. She fills out forms, such as one for Paul, a bull she spots off a dirt road. He's 22, three or four tons, gray, wrinkled, and majestic: Time: 7h15. Location: Warthog Road. Weather: Hot/Sunny. Comments: V relaxed, feeding.

There are thrills in her work, for sure - seeing elephants play like children in the water; watching a teenage bull show off by knocking over a tree; speeding away from a grumpy - charging - female. But what drives Delsink is the hope that, eventually, her research might shift the emotional debate over southern Africa's elephants, which have rebounded from the 20th-century decimation of ivory poaching. They're protected by a UN ban on ivory sales and a South African ban on culling - the killing of "excess" elephants in reserves. But there are so many elephants - between 12,000 and 14,000 in the largest park - each eating up to 1,000 pounds of vegetation a day, that there are concerns they threaten other species. In South Africa, some game managers want to renew culling. Others suggest moving the elephants to spread their impact.

Delsink is working on a third option: Contraception. By slowing population growth, she says, ecologists could better manage the species and its impact. So, in 2000,she and other scientists began injecting the Makalali herd with a contraceptive. Skeptics say it's irresponsible to take reproduction from elephants, that it will change their behavior, that when humans try to play God, bad things happen. That's why Delsink is watching, to see what happens with elephants on birth control.

"The focus on [elephants] is huge, the problems are huge," says Rob Slotow, a professor at the University of KwaZulu Natal who advises Delsink. "Contraception ... is a major intervention. It's important to study it as it is happening."

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Elephants symbolize big game, the lure of Africa. They also represent cash. Much of the tourism industry revolves around animal safaris. So while elephant contraception might sound like the punch line of a bad joke, in the macho world of African wildlife management, it's more likely to prompt fisticuffs than chuckles. Delsink gets yelled at regularly. Recently, as she quizzed a conference speaker about elephant population control, another attendee turned on her. "He started saying ... 'Well, you're such a bunny hugger.... Oh, I suppose you're one of the types who don't eat meat,' " she recalls, fingering her gold elephant pendant.

The contraceptive used in Makalali has been used in zoos to prevent inbreeding and on wild horses and deer in the US. Scientists began testing it in 1995 on elephants in Kruger National Park.

"We did basic science to see if it could work," says Henk Bertschinger a University of Pretoria biologist. "We did field studies and saw that it was also reversible if you discontinued vaccination."

The vaccine works by changing the membrane around female eggs to block sperm from fertilizing them. Cows are injected yearly by dart. After the Kruger trials, the scientists decided to move their experiment to a small reserve where they could identify and watch every vaccinated elephant.

That's when they found Delsink at Makalali. She was the perfect researcher - she'd already started identifying elephants there, often by using ridges in their ears and giving them names. "It's not that hard," she says. "It's just that most people, when they look at an elephant, they only see an elephant."

Delsink has collected the world's best data on how elephants behave on birth control, says Mr. Bertschinger. She can evaluate movement patterns, how the herds act together and apart, how bulls treat cows, and so on. So far, the numbers show no significant impact. Her work has convinced at least seven other small reserves to use contraception to control elephant populations.

"People used to think, This is ridiculous, a waste of money,' " Delsink says. "Now ... people are sitting up and taking notice."

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Delsink holds up an antenna, listening for distinctive radio-collar beeps. "Kwatile," she says, with a smile. Kwatile, or "Angry One" in the local Tsonga language, is at 55 the oldest matriarch in Makalali. A prickly, sagging elephant with one tusk, she's charged almost every ranger on the reserve. A younger Delsink wouldn't have gone near her.

"I was really green, really new as a ranger," she says, shaking her head at the memory of being charged by two cows that "came out of nowhere" when she had a French family in her truck. But now, when she sees the old elephant she coos: "Hey, Kwatile, hey old girl." She's comfortable because she understands elephants better. "I'm not the type of scientist that remains aloof," she says. "I didn't name them Bull 1 to 10. I need to know them."

She knows when they're nervous (their tails are up). She knows the young bull's mock charge. She knows how the breeding herds wait for the matriarch to move, and how they all follow her.She also knows how "auntie" and "nanny" elephants care for other cows' offspring. She sees how mothers stay close to their calves for years. Parenting is so central for elephants that Makalali allows cows to have at least one offspring.

Delsink also knows how elephants recognize the bones of their family members and seem to grieve. In fact, ecologists are still dealing with the effects of pre-1995 culling in Kruger. Many young elephants spared grew up unnaturally aggressive, killing rhinoceroses for no apparent reason. Scientists now believe that culling must take out whole herds at once, if done at all.

Kwatile, Delsink says, will be the first elephant in Makalali to die of natural causes. She wonders how the other elephants will react. And Delsink will be there, of course, to watch and record.