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In Body Image

Is there any kind of fence that can make humans and elephants good neighbors? It’s a question Dominique Gonçalves has had to ponder as she leads the elephant ecology project at Mozambique’s Gorongosa National Park, which is not surrounded by a physical barrier.

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A number of pioneering studies throughout Sub-Saharan Africa over the past several years showed a solution that was simple and natural: bees. As it turns out, the tiny, ubiquitous honeybee has the power to terrify a mammal that’s 22 million times its size.

In fact, even the sound of the insect’s buzz is enough to send a family of elephants into a panic, showed studies by Lucy King, an Oxford zoologist and preeminent researcher in human-elephant coexistence at the nonprofit Save the Elephants. Upon hearing the telltale hum, elephants will run, kick up dust, shake their heads as if trying to swat the bees out of the air, trumpeting distressed warnings to other elephants as they flee.

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Of course, a bee’s stinger can’t penetrate the thick hide of an elephant. But when bees swarm—and African bees swarm aggressively—hundreds of bees might sting an elephant in its most sensitive areas, like the trunk, the mouth, and eyes. And it hurts.

The bee has the power to terrify a mammal that’s 22 million times its size.

Building on King’s insights, Paola Branco of the University of Idaho conducted a massive two-year-long experiment in Gorongosa that culminated in a 2019 paper she co-authored with King, Marc Stalmans, Gorongosa’s director of scientific services, Princeton zoologist Robert Pringle, and others.1 Their research aimed to settle tensions between human farmers and the park’s growing population of marauding pachyderms—with the help of bees.

Although elephants are peaceful by nature, they can and will trample grain, swipe crops, topple down silos, and knock down entire houses. Given half a chance, elephants from the fenceless sprawl of Gorongosa in the Lower Rift Valley will steal across the Pungwe River—which acts as the southern border between the million-acre park and the rest of rural Mozambique—stomping into villages in search of a meal.

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Humans share blame in the squabble. Natural habitats for elephants are rapidly being tilled into croplands, encroaching on food sources, often leaving the animals little choice but to ransack and steal. And while the population of African elephants has been precipitously dropping, the number of humans in Sub-Saharan Africa continues to skyrocket, rising from 930 million in 2012 to 1.2 billion in 2022, data from the World Bank show.

The result is that elephants and people are often competing for the same resources. The animals—which typically eat about 300 pounds of vegetation a day—can decimate an entire farm’s harvest overnight.

In a way, it’s not a terrible problem to have, says Gonçalves, who grew up in the town of Beira, a few hours away from Gorongosa.

The Mozambican civil war, which raged from 1977 to 1992, saw 95 percent of Gorongosa’s large animals killed. The impact on elephants was especially profound. Slaughtered by warring troops who traded their tusks for more guns, the park’s pre-war population of elephants dwindled from 4,000 to only about 200 by the time the conflict ended. Thirty years on, says Gonçalves, that population is bouncing back and now numbers a little more than 1,000. The crop raids are a side effect of that recovery.

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But straying elephants cause havoc for small-scale subsistence farmers in Gorongosa’s buffer zone, the liminal area that stretches around the 1,500 square miles of the park and is home to more than 200,000 people. The more elephant numbers bounce back, the more of them there are to go on nighttime ransacking missions.

“It’s a question of how humans and elephants are overlapping,” says Gonçalves. “If there are agricultural plots, that can create situations of conflict, when elephants either eat or trample or destroy. That has a huge economic security impact for farmers.”

In Body Image
BUZZ OFF: Buckets of bees are strung on a fence wire along a river in Mozambique. When elephants trip the wire, bees swarm out of the boxes. The elephants hightail back to where they came from. Courtesy of Gorongosa National Park.

Most subsistence farmers don’t have the resources to surround their plots with expensive wire fences, and often must resort to less effective deterrents like banging sheet metal to scare elephants away, burning tires to produce acrid smoke, or lying in wait in the bushes at night with flashlights and fireworks to startle the animals.

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These confrontations can prove lethal for both sides. In July of 2022, five people harvesting their crops in the Mozambican province of Cabo Delgado—870 miles northeast of Gorongosa—were trampled by elephants from the Quirimbas National Park. On occasion, humans retaliate. In Kenya, for instance, wildlife authorities shoot between 50 and 120 elephants per year.

“That’s the worst-case scenario,” Gonçalves says. “Both people and elephants end up being dead.” So she and her colleagues at Gorongosa decided to intervene to keep the two sides happy.

It began, as many science things do, with an experiment. In 2017, researchers strung a series of fences at well-trafficked elephant crossing points along the Pungwe River. Some of the fences relied on methods of elephant deterrent already popular among small-scale farmers, such as twine soaked in chilis.1 But between others, the researchers ran bailing twine from which they suspended hives populated by the famously irascible African bee, a species nearly identical to its European and North American cousins—but for its more aggressive tendencies. Still others combined chili-coated twine and bee hives.

The researchers then tranquilized and fitted 12 male elephants—males being more apt to forage in croplands—with GPS collars. Satellite data pinged from the collars, combined with the observations of local community members, allowed the researchers to keep exacting tabs on where the elephants wandered and whether the experimental fences prevented them from stumbling into neighboring farmsteads to rummage.

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Sure enough, the fences worked. The chili fences reduced elephant river crossings by 80 percent—while the beehive fences thwarted a whopping 95 percent of cross-river forays by the animals. (Beehives strung on twine coated in chilis were, surprisingly, the least effective. King and her co-authors surmised that the coating weighed the twine down, making it easier for elephants to simply step over it.)

Cameras placed near fences involving beehives showed that the elephants would trip the bailing twine, thus shaking the suspended beehives. Immediately, this would stir the bees to action, and they would swarm and mount an attack. In footage taken at night, shadowy silhouettes of peeved elephants can be seen turning tail and lolloping in unison out of the frame.

Beehive fences thwarted a whopping 95 percent of forays by the animals.

The true beauty of this method, write Branco and her coauthors in the study, is that it allows discontinuous fencing to block key corridors used by elephants as they go on crop raids rather than fencing individual farms or entire nature preservers, like Gorongosa—which both for the farmers and the park could prove prohibitively expensive, running into the thousands and even tens of thousands of dollars. To build 15 hives and string them from posts, Branco and her team spent a total of $773.

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The results at Gorongosa jibed with those from another field study that King conducted in Kenya in 2017.2 In that experiment, researchers strung beehive fences around 10 farms that were located near a nature preserve, reducing elephant raids by 80 percent. Bee fences have also been found to be an effective deterrent against crop raiding Asian elephants as well, showed a 2018 study King conducted in Sri Lanka.3 In that case, merely playing recordings of angry bees through speakers in the field was enough to cause the elephants to flee.

Gonçalves says the bee barriers set an important precedent for future conservation efforts by offering a nonlethal method of control that doesn’t create divisions between the park and the people who live near it.

Bee fences alone aren’t enough. Other animals that are less flustered by bees, such as baboons and honey badgers, can be drawn to the honey the bees produce, disturbing the hives to the point at which the bees themselves take flight and move out. King’s studies in Kenya, however, suggested that small cages can be placed around hives to prevent them from being disturbed by these other foragers. The dry seasons, too, can dampen bee populations in hives as they flee and search for moister climes.

But the elephant intellect, says Gonçalves, proves the biggest obstacle to a static set of beehive fences. They have not, for instance, deterred clever elephants from seeking out alternative crossing points and taking up near-permanent residence in the buffer zone.

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Indeed, Stalmans says, sometimes a traditional, or even electric, fence is the best resort—but even those prove, over time, to be no match to an elephant’s keen navigational sense. Just as they are smart enough not to get stung or shocked, they’re also smart enough to simply chart routes around most human-made impediments and find their way to nearby farm settlements.

It is here that Gonçalves joins efforts with Gorongosa’s human-wildlife coexistence team. Together, they chart the peregrinations of known elephant families that have been collared with GPS devices and can thereby spot areas of potential human-elephant conflict before they erupt.

Lead photo by Kevin Berger.

The  Nautilus Gorongosa Series is published in partnership with the Howard Hughes Medical Institute’s Science and Educational Media Group.

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1. Branco, P.S., et al. An experimental test of community-based strategies for mitigating human-wildlife conflict around protected areas. Conservation Letters 13, e12679 (2019).

2. King, L.E., Lala, F., Nzumu, H., Mwanbingu, ,E., Douglas-Hamilton, I. Beehive fences as a multidimensional conflict-mitigation tool for farmers coexisting with elephants. Conservation Biology 31, 743-752 (2017).

3. King, L., et al. Wild Sri Lankan elephants retreat from the sound of disturbed African honey bees. Current Biology 28, R64-R65 (2018).

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