African elephants are the largest land animals on Earth. Growing as tall as a basketball goal and weighing more than three minivans, these beloved behemoths are famously social, intelligent, emotional — and hungry.

Wise enough to know an easy meal when they smell it, wild elephants often leave nature preserves at night to raid crops from nearby farms. Even a small herd can wipe out a full year's harvest in one night, leaving farmers frustrated and resentful. If your corn is coveted by 7-ton juggernauts, what can do you do?

Retaliation rarely turns out well, since non-fatal injuries can just make elephants mad, leading them to attack and sometimes kill humans. When farmers do kill elephants, they add to growing pressures like poaching and habitat loss that are already pushing the animals to extinction. Fences are another option, but they require extreme strength or a deterrent like electricity — neither of which is cheap. Elephant-proof fences can cost up to $12,000 per kilometer, a tall order for subsistence farmers.

The secret to co-existing with elephants, however, isn't necessarily to think big. Rather than using high walls or high voltage to keep elephants away from crops, one of the most buzzworthy ideas relies on an insect about the size of a paper clip.

honeybeeBees tend to swarm inside elephants' trunks when they attack, a pain the giant mammals never forget. (Photo: Shutterstock)

beehive fenceA beehive fence protects fields bordering Kenya's Tsavo East National Park. (Photo: Lucy King/Elephants and Bees Project)

Time for plan bee

Elephants, despite their thick skin and imposing heft, are terrified of bees. And for good reason: When elephants disturb a beehive, they trigger its defensive swarming response, which often leads to bees stinging the sensitive tissue inside their trunks. Being such intelligent animals, elephants have learned to associate bees with excruciating nose pain. They even have a specific "bees!" alarm call, and they're known to flee the sound of buzzing alone — as seen in the video below:

Couldn't farmers just repel elephants with audio recordings of bees? Maybe briefly, but elephants are too clever to buy a ruse like that for long. Like other noise-based scare tactics, it stops working once elephants realize the sound is an empty threat.

As scientists have shown in recent years, however, a fence made of actual bees can be an effective, even profitable way to keep elephants at bay. It's a brilliantly simple strategy, hanging beehives from wooden posts at 10-meter intervals with a long metal wire linking them all together. When an elephant hits the wire, it shakes the hives and sends angry honeybees swarming into a defensive frenzy.

beehive fenceAn elephant studies a beehive fence at night, as seen by a remote camera. (Photo: Lucy King/Elephants and Bees Project)

The best offense is a good bee fence

The idea for beehive fences dates back at least to 2002, when researchers with Save the Elephants reported that elephants avoided trees containing bee colonies. This led to a new line of research about elephant-bee dynamics, including a beehive fence concept devised by Oxford University zoologist Lucy King. After a successful 2008 trial in Kenya, King continued tweaking and testing the design in new locations.

It became the subject of King's doctoral thesis in 2010, as well as several scientific studies, and has earned her prestigious awards like the 2013 Future for Nature Award, the 2013 St. Andrews Prize for the Environment, and the 2011 UNEP/CMS Thesis Award. She now leads the Elephants and Bees Project (EBP), a collaboration among Save the Elephants, Oxford University and Disney's Animal Kingdom that helps farmers build beehive fencing near fields plagued by crop-raiding elephants.

beehive fenceLucy King gives a bee-fence tour in Kenya, where 50 to 120 elephants die per year in retaliation for crop raids. (Photo: EBP)

"When I first heard Lucy King speak at a conference, it was just one of those moments where I immediately wanted to be involved," says Hayley Adams, a wildlife veterinarian whose charity group, Silent Heroes Foundation (SHF), is now working to build a beehive fence in Tanzania. "It's one of those nice, holistic concepts that I think everyone understands the importance of and everybody benefits from."

At least 10 countries now have beehives fences, and more are in the works. Their success rate is about 80 percent, and they're cheap to build with local materials, costing $100 to $500 per 100 meters. On top of that, they also make money.

Elephant-Friendly HoneyRaw, unheated honey from beehive fences is sold with an "Elephant-Friendly Honey" label. (Photo: Lucy King/EBP)

Sweetening the deal

"To my knowledge, beehive fences are the first elephant-deterrent fence that has been invented that actually makes the farmer more money than what it costs to maintain the fence," King writes in an email to MNN, "so it's a money-producing project in its own right."

EBP buys the raw honey "at a generous price," its website explains, ensuring farmers have backup income and stay engaged in the project. The honey is processed without heat or pasteurization, bottled with an Elephant-Friendly Honey label and sold.

The bees also pollinate farmers' crops and nearby wild plants, providing an ecological and economic boost to the surrounding area. And unlike electric barriers, beehive fences require no electricity and don't compete with crops for space. That's all icing, though — scaring elephants and making honey are the bees' bread and butter.

"[A]lthough the fence is only effective at keeping around 80% of the elephants out," King writes, "it more than makes up for that 20% of elephants that do break through by providing an alternative income, which can be managed by either men or women."

beehive fenceA farmer in Botswana poses with a new beehive fence, hung under a traditional thatched roof. (Photo: Lucy King/EBP)

Elephant in the room

It's worth noting farmers are far less dangerous to elephants overall than poachers are. An estimated 30,000 to 38,000 African elephants are killed each year by poachers seeking ivory, outpacing the species' reproduction and raising the specter of extinction. But Africa's elephants have also lost more than half their total habitat since 1950, and only 20 percent of what's left is under formal protection.

Faced with this kind of pressure, they need all the friends they can get. And while beehive fences may seem like another hardship for the already-embattled animals, a few stings in the trunk are worth it if they keep more elephants alive.

African elephants are a keystone species, performing ecological services like digging water holes in dry riverbeds, spreading tree seeds in their dung and creating forest trails that act as fire breaks. Subtle benefits like these are easy to overlook, but by helping farmers profit from elephant-friendly honey, beehive fences can give local humans a clearer financial stake in the animals' continued existence.

"It's a nice way for communities to appreciate their elephants, to appreciate the resources they have," Adams says. "A lot of times rural communities resent the wildlife around them because don't understand why it's of value. So if they can make money by selling honey, that could make a big difference."

beehive fenceBeehive fences need regular checkups, since elephants can quickly exploit a struggling colony. (Photo: Lucy King/EBP)

There's a precedent for this in eco-tourism, which can make an African elephant worth nearly $23,000 per year to its local economy. Since they live for up to 70 years, that means each elephant is worth about $1.6 million over its life span — roughly 76 times the one-off profit a poacher makes by selling a pair of tusks.

Beehive fences may have less influence on poaching trends, but they can at least improve elephants' overall safety by curbing conflict with local communities. And since they directly help farmers in multiple ways, the fences provide a low-risk supplement to the broader, more complex effects of eco-tourism.

"It's very economical, so there's not a lot of overhead or oversight required," Adams says. "And it has a ripple effect — if you install a bee fence on one farm, pretty soon a neighbor hears about it and wants one, too."

beehive fenceMany bee fences use two trees as "regrow posts" to hang each hive along the edge of a farm. (Photo: Lucy King/EBP)

Hive mind

King has helped launch beehive fences in several countries, and her group is working on another in Kenya's Tsavo region. But with the concept well-established, she's shifting to a less centralized, more open-source approach. "We are really focusing on welcoming different researchers and project managers to our Elephants and Bees Research Center," she writes, "to train them up and send them back to their various project sites around the country and continent to try the idea for themselves."

One person King has inspired is Adams, whose group is building a beehive fence outside Tanzania's Ngorongoro Conservation Area to protect nearby corn and sorghum fields. That project got a boost in late 2015, when the Ian Somerhalder Foundation awarded it a $6,000 grant, money that will pay for the fence itself plus expenses like logistics, training, data collection and publication of results.

"First we'll need to evaluate if it's a success, then we'd like to scale up, develop a program in which people can apply for training," Adams says. "And then look toward bringing it full scale and the community aspect of harvesting honey. It will become more of a business venture moving forward to market the honey."

Beekeeping is already a familiar enterprise around Ngorongoro, with natural hives often hung from acacia and baobab trees. But like EBP and other groups that support bee-fence projects, SHF will still offer training for farmers. There's even a step-by-step construction manual, courtesy of King and EBP, that includes guides for using natural hives as well as Langstroth and top-bar varieties, like this one:

beehive fence diagramA diagram of a bee fence made with Kenyan top-bar hives, one of several hive options. (Image: Lucy King/EBP)

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Unfortunately, bees can't save elephants on their own. They can, however, remind us that the best solution to a problem has often been under our noses all along. The same kind of nature-inspired ingenuity that helped King develop beehive fences, for example, has also led to other low-tech deterrents like chili-pepper fences, which target elephants' sensitive noses with capsaicin instead of bee venom.

More importantly, beehive fences offer a simple way to help communities not only tolerate elephants, but see them as benefactors rather than bandits. Combined with changing attitudes about ivory in China, King says that kind of paradigm shift could actually have an impact on elephants' long slog toward extinction.

"[A]n African continent without wild elephants would be a significantly poorer place, both environmentally and culturally. It would be a disgrace if it's our generation that lets them die out on our watch," she writes. "We have to find a way for people and elephants to live in harmony, and I believe beehive fences are a valuable tool in the toolbox of options for them to co-exist better in the future."