Big Data

In Southern Africa, five countries united by a shared vision for conservation undertake an elephant survey of historic proportions

Small map showing KAZA region in Africa

Netsai Bollmann knows what it’s like to coexist with elephants.

In the course of her work in the Kavango Zambezi Transfrontier Conservation Area, known as KAZA, Bollmann frequently drives from her home in Botswana to Victoria Falls on the Zambia-Zimbabwe border. More often than not, she yields the right of way to the giant gray pachyderms.

“Sometimes it’s a lot of them, and you wait for them to cross, or sometimes you try to push your way through,” she says. Once, she arrived home after work to find an elephant had wandered into her yard; someone had left the gate to the property open. Her neighbor herded it out with his old 4x4.

“There’s nowhere in KAZA that you will not see elephants,” she says. “They’re everywhere. They’re part of our lives.”

Carved out of the convergence of Angola, Botswana, Namibia, Zambia, and Zimbabwe, KAZA is the largest terrestrial transboundary conservation area in the world. Bigger than California, the 200,000-square-mile area encompasses three World Heritage Sites and numerous national parks, forest reserves, and other conservation areas. It’s also home to about 2.6 million people and approximately half of Africa’s remaining savanna elephants (Loxodonta africana).

And while the African savanna elephant is officially listed as endangered, numbers in KAZA appear to be stable or increasing. Past survey data indicates that around 220,000 roam this biologically rich landscape. That’s about one six-ton herbivore per square mile—or one for every 12 people living in KAZA.

“It’s a lot of people,” says Bollmann, “and it’s a lot of wildlife.”

With agriculture, homes, and kids going to school, interactions aren’t always as benign as an elephant lolling in the garden. “Human-wildlife conflict is a real problem,” she says, “with sometimes severe consequences.”

When the five countries established KAZA in 2011, they envisioned conservation and tourism driving the region’s economy, with communities playing a critical role as both stewards and beneficiaries of wildlife. But coordinating conservation efforts across this immense landscape and among multiple countries is an ongoing challenge.

Exacerbating that challenge has been a lack of reliable data about wildlife populations. “Without a good understanding of where the elephants are, and what their numbers are, you’re planning in the dark,” Bollmann says.

In 2022, she was part of a team that set out to help fill that knowledge gap. As the program manager of the KAZA Secretariat, the entity charged with administering the countries’ shared agenda, she helped facilitate a monumental effort to determine the number and seasonal distribution of savanna elephants in KAZA.

With technical and financial input from WWF, and with support from a global pool of donors and partners (see page 28), in August 2022 a 47-person team—including pilots, biologists, and data analysts—launched what they hoped would be a definitive aerial survey.

As Bollmann well knew, pulling it off would be no small feat. “Honestly,” she says, “I’m 41, and I have developed two white hairs since I joined KAZA. One of them is from the beginning of the survey.”

Mutual goals

A herd of elephants in Botswana’s Chobe National Park.

When it comes to protecting the largest viable and contiguous population of elephants in Africa, the KAZA partner countries “do not take lightly the responsibility they carry for— and on behalf of—the rest of the world,” says Nyambe Nyambe, executive director of the KAZA Secretariat, adding that the goal is “a thriving, wild population.”

Meeting that responsibility requires addressing a host of issues—not least, ensuring elephants have room to roam. The largest land mammals on Earth often range over huge distances, oblivious to national borders as they search for water, food, and mates. Because they need so much space, landscape-level planning and transboundary cooperation among KAZA’s countries are essential to the species’ survival—and that of many other species, too.

Having up-to-date population numbers—as well as a clearer picture of when and where the animals move, especially between protected areas—will enable better coordination and allow partner countries to make more informed decisions, says Nyambe.

Two men in a small plane cockpit

Ashley Mudungwe (left), a senior ecologist with the Zimbabwe Parks and Wildlife Management Authority, and Fungai Muroki, an ecologist with BushSkies Aviation, on a survey flight.

With more accurate data, he explains, conservationists can pinpoint where greater efforts are needed to secure wildlife dispersal areas—key corridors that allow elephants to move across the landscape—or to remove or reevaluate barriers that prevent the animals from migrating freely. Better data will also identify where to scale up efforts to help communities deal with large numbers of elephants.

“Currently the largest elephant populations are in Botswana and Zimbabwe, and these two countries are facing significant pressure from human-elephant conflict,” says Nyambe. “How can we deal with it? KAZA provides an opportunity for elephants to move from areas of local overpopulation to areas of local underpopulation.” (Following decades of war and poaching, numbers are especially low in parts of Zambia and Angola.)

At the same time, updated numbers will help KAZA partner countries know where to invest in tourism.

“From a tourism perspective, we’ve got thousands of beds across the KAZA landscape,” says Bollmann, who spent 14 years in regional tourism development before joining the KAZA Secretariat. Ecotourism is a significant contributor to the economies of partner countries. Knowing more about elephants will further develop the wildlife economy—and allow the people of KAZA to not only put food on the table but also enjoy “opportunities for real, meaningful quality of life,” she says.

For those reasons and more, in 2019 the five countries agreed that a count of elephants in KAZA was long overdue.

Surveying giants

The last major elephant survey in Africa took place from 2013 to 2016. Known as the Great Elephant Census (GEC), it was audacious in scope, involving more than 90 scientists and 286 crew members representing 18 countries.

The census painted a broad-strokes picture of astonishing loss, identifying a 30% decline in the total savanna elephant population across the continent in just seven years—largely a result of poaching for elephant ivory, human-wildlife conflict, and war. Even in KAZA, the largest savanna elephant stronghold, researchers found pockets of what they called “catastrophic” declines: The Sebungwe Region of northwest Zimbabwe, for example, suffered a 75% loss between 2006 and 2014.

“Without a good understanding of where the elephants are, and what their numbers are, you’re planning in the dark.”


These findings drew global attention to the plight of Africa’s elephants. They also proved that a census of such massive scale was possible, says WWF-Namibia’s Russell Taylor, the conservation planning advisor and veteran biologist who served as technical lead in developing the KAZA survey. “We learned a lot from the GEC,” he says, citing the importance of securing government support and ownership, taking a team approach, and being flexible, nimble, and able to make timely decisions.

However, “there was no synchronization of the sort that we know should happen,” says Taylor, and “no cross-border coordination, although attempts were made.” In KAZA, the GEC surveyed Angola, Botswana, Zambia, and Zimbabwe (and WWF funded an independent survey of Namibia). But the counts were done at different times and in different years, meaning some elephants may have been tallied two or more times and others not at all as they moved across international borders.

When in May 2019 the KAZA partner countries decided to undertake a KAZA-wide, synchronized aerial survey, it was a key part of a larger strategy to shore up the elephant population amid an epidemic of wildlife crime. Despite the countries’ commitment to conserving elephants, until then they hadn’t agreed on a means to that end. More precise data was needed to help them make tough decisions.


Most survey flights took place in a Cessna light aircraft with a four-member crew: a pilot, two observers, and a recorder. The rear-seated observers—one left, one right—scanned the landscape, announcing elephant sightings and photographing herds of more than 10. The recorder (often a seasoned survey biologist) wrote down all data and noted GPS coordinates. Researchers also used aircraft cameras and a machine-learning algorithm to help automate species identification.

The survey was planned as a two-year project. (“A plan is nothing; planning is everything,” quips Taylor.) By October 2019, the team had developed its design, but the COVID-19 pandemic soon wreaked havoc on the timeline. Once it was safe to move forward, the organizing partners realized they’d need to hit the ground running to complete the count in 2022. Though the surveying would last only two months, timing was key. In July 2022, the team led a weeklong workshop to select and train observers.

“We were working against a tight timeline linked to the weather and climatic conditions,” Nyambe explains. In the dry months of August, September, and October, most trees and shrubs are leafless, making it easier to see wildlife from the air. Moreover, when it’s dry, normally peripatetic pachyderms mostly stay put around permanent water sources. When the first rains come, however, seasonal pans are replenished, luring them to fresh water and forage, and “elephants start moving all over the place,” Nyambe says.

Bird’s-eye view

Toward the end of the dry season, strong winds and bush fires in Zimbabwe’s Sebungwe Region generally create poor visibility and extremely hazardous flying conditions. But on August 22, 2022, it was calm and clear as a six-seater Cessna 206 bush plane took to the skies about an hour after sunrise from an airstrip near Matusadona National Park.

The pilot did his best to hug the rugged terrain below, balancing safety with optimal height for viewing elephants. Two observers called out sightings—creating an audio recording over the voice-triggered intercom—while a fourth crew member logged them using a GPS unit and handwritten notes. The plane returned safely to the airstrip at 11 am sharp.

Over the next several weeks, a series of carefully synchronized, often simultaneous, flights traversed the expanse of the KAZA landscape, from Botswana’s Okavango Delta to Zambia’s Kafue National Park and Victoria Falls. As the planes flew above scrubby savannas, vast grasslands, and snaking rivers, each crew followed a rigorous and methodical approach.


Below: Views during one flight over Bwabwata National Park in northeastern Namibia.

Photographer Ty-Mason James.

Darren Potgieter in the cockpit.

Darren Potgieter, an experienced wildlife surveyor who led the field effort, says crews observed the aerial survey standards set by CITES (Convention on International Trade in Endangered Species) called MIKE (Monitoring the Illegal Killing of Elephants). Using this widely adopted method, they mostly conducted transect sample counts, flying in straight, evenly spaced lines over relatively flat ground, with observers counting elephants in a carefully calibrated field of view. In areas where maintaining a consistent height over precipitous peaks and hidden gorges wasn’t possible, teams performed block counts.

Flights took place in the early mornings—before temperatures in the planes would become unbearable and wildlife on the ground would seek shade. To ensure maximum visibility, pilots flew low and slow, with a search rate of one square kilometer per minute. “That’s part of the rigor we built into the survey,” says Taylor. “We control the height; we control the speed. You can’t go much slower, else you’ll crash.”

Because of the complex, sometimes dangerous nature of the work, flight crews comprised highly trained, thoroughly vetted experts. Each included a skilled pilot not only capable of low-level flying—with its greater risk of collisions and reduced time to recover after stalls or engine failures—but also able to take off from and land in treacherous terrain. Crews were chosen for their ability to accurately identify species, their visual acuity (“We bought one man a pair of glasses,” says Taylor), and their fortitude to endure hot, bumpy flights that could stretch to nearly four hours.

Longer than that, and crew fatigue would lead to bad data, Potgieter says.

“I’m not ashamed to say I did not participate,” Bollmann says, deadpan. “Once that flight takes off, it doesn’t matter how sick you get on that plane. It’s not gonna land—because it can’t. Otherwise it compromises the count. There was nothing anyone was going to do to get me on one of those planes.”

Heartbeat of coordination


The KAZA aerial elephant survey was made possible with support from the following institutions:

The Paul G. Allen Family Foundation

The German Federal Ministry for Economic Cooperation and Development through KfW

The Dutch Postcode Lottery through the KAZA Dream Fund

CITES Monitoring the Illegal Killing of Elephants (MIKE) Programme through funding from the European Union

USAID’s Combating Wildlife Crime in Namibia and the Kavango-Zambezi Area Project

The UK Foreign, Commonwealth and Development Office

The Environment and Protected Areas Authority (EPAA), government of Sharjah, United Arab Emirates

The US Fish and Wildlife Service African Elephant Conservation Fund

Happily grounded, Bollmann oversaw myriad logistics, including organizing meetings to apprise ministries, donors, and partners of progress and setbacks, supporting the team in procuring aircraft, and purchasing fuel and equipment to keep as many as six planes aloft at one time.

Logistics also included the arduous task of securing the overflight permits from each country that would allow for tightly synchronized flights. To avoid the risk of over-or undercounting elephants, the survey was designed to minimize the flight time over areas where the animals frequently crisscross international borders—between Botswana and Zimbabwe, for example.

That meant obtaining and submitting copious documentation to civil aviation authorities, such as permission letters from every airstrip and details about each flight’s aircraft and crew.

Acquiring the overflight permits made for some “sleepless nights and restless days,” says Nyambe.

Bollmann concurs. In fact, she blames her second white hair on them: “Now for the rest of my life, it will remind me of the elephants,” she says with a laugh.

The government of Botswana loaned the project an operations room that Potgieter called the heartbeat of coordination. Based in Kasane, the former parks authority conference room had been used as a storeroom before Bollmann supervised its rebirth as the survey’s data hub. Four days before the first flight, it was up and running, with reliable electricity and internet, and a row of workstations with two big wall-mounted monitors and an even bigger 2022 calendar—a constant reminder of the short window to pull off the survey.

There, Potgieter’s colleague Elsa Bussière, the survey’s science and technology manager, presided over six data analysts borrowed from the KAZA partner countries. Their inclusion was one way to ensure transparency, Potgieter says.

As permits were granted and flights got underway, satellite technology allowed the ops room to monitor the trajectory, height, and speed of every aircraft in near real time. The data came pouring in, and the analysts began the monthslong process of making sense of it all.

Getting to ‘Yes’

For those involved in the survey, anticipating obstacles and responding to setbacks often felt like playing a game of Whac-A-Mole. Data might be corrupted or poorly recorded, meaning extra work in the ops room to validate it. Potential mechanical failures, meanwhile, were always top of mind.

“A couple of days’ downtime because you’ve got an aircraft engine problem, or a propeller problem, or an alternator problem? ... You can’t afford to lose those days,” says Taylor.

Another challenge: ensuring all five KAZA partner countries were kept well-informed so they could provide input and approvals along the way. Bollmann explains that it was crucial at each step to get five yeses to ensure everyone remained fully supportive as plans evolved.

Given the vagaries of weather and wildlife, flexibility and adaptability were crucial, and their detailed plan anticipated challenges, allowing for go and no-go moments.

“We were prepared to say, ‘If this is not done by this day, then we cannot proceed,’” says Nyambe. “There were challenges, trust me. But everybody rallied together. The level of cooperation was amazing.”

Crunching the numbers

About the survey

The 2022 KAZA Elephant Survey was designed to help estimate elephant numbers, but it also provided crucial information about where the mammals live, their migration patterns, and how populations are changing—all information that can be used to better protect them.

Read more

In the end, the team had clocked almost 700 flying hours covering the nearly 121,000 square miles where 99% of KAZA’s elephants live.

“When that last flight took place, we all breathed a little,” says Bollmann.

With the final data in hand, Potgieter and Bussière spent the next several months crunching numbers to share with the KAZA partner countries and to be scrutinized by external independent reviewers before the results were officially released to the world.

Their report, released in August 2023, was encouraging: It estimated a total of 227,900 elephants in KAZA, indicating a stable population. It also identified high elephant mortality in certain regions, underscoring a need for further research, monitoring, and tailored conservation initiatives—findings that reinforce recommendations made in the KAZA Elephant Sub Working Group’s latest policy brief, which provides guidance on securing and maintaining elephant movement corridors and landscape connectivity.

Both the results and the survey itself were sources of pride for all involved. “I’ve not known a better-executed survey,” says Taylor.

Moreover, knowing that these countries could come together to complete such an enormous project gives Bollmann hope for their ability to protect the future of elephants.

“The five countries made a decision that they’re going to pull off something that was going to be a remarkable challenge, and they did it together,” says Bollmann. “They prioritized it, they planned together, they dealt with challenges together.... To see them working together and being a part of that—as an African person from Southern Africa—made me very proud.”






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