Engineering student Saif Bhatti has created an acoustic device that can detect poachers’ gunshots.
By Amanda Morris
Image: Ami Vitale
You can tell a lot about a poacher by the way they dehorn a rhinoceros.
Was the horn hacked off crudely — snout and all — with a machete? Or was it removed skillfully with a sharp, scalpel-like instrument, right along the thin partition of cartilage that separates horn from bone?
As Saif Bhatti bumped along the dirt back roads of Thornybush Game Reserve in South Africa, he was unsure which one they might find. He sat shotgun in an old pickup truck next to the reserve’s security manager, who held his phone in his right hand, gripped his radio in his left and steered through the savanna with his elbows. Someone in the area had reported two gunshots fired around 6 a.m. But in the sprawling 35,000-acre park, it was hard to know where to search.
With more than 8,000 poached in South Africa from 2010 through 2019, rhinos are likely to become extinct within our lifetime. Habitat loss is partially responsible for the rhinos’ dwindling numbers. But, overwhelmingly, poaching remains the largest threat. On the black market rhino horn is worth more than gold, which fuels illegal hunting.
The search for the poachers in Thornybush took place throughout the day and night and included helicopter, patrol and canine units at different times.
It wasn’t until the next morning that the security manager’s radio crackled to life: His team had discovered the carcass of the reserve’s last female black rhino.
The first bullet had ripped through the right side of the rhino’s abdomen. As she turned to run, a second shot blew through her left shoulder. She finally stumbled to the ground and — likely painfully and slowly — bled to death. The rhino was pregnant; the fetus did not survive.
Where the rhino’s horns once perched upright, now there were exposed sinuses, glistening and yawning toward the sun.
“The horn had been expertly removed,” Bhatti says. “It was not this group’s first poach.”
But if Bhatti’s new technology works as well as he imagines, this poach could be one of their last.
McCormick senior Saif Bhatti visits South Africa’s Thornybush Game Reserve in August 2019 to field-test Renoster.
Cold-Hearted Reality and New Motivation
In April 2019 Bhatti began developing Renoster, a smart listening device that detects gunshot sounds in the savanna. (The name means rhinoceros in Afrikaans.) The devices, which are slightly bigger than the palm of a hand, sit in trees, scattered throughout the reserve. When a unit detects a gunshot, it automatically sends a signal and location to the game rangers’ operations hub. Having that location (within a 100-meter radius) means there is no aimless driving or needless dispatch of helicopters and canine search units. Rangers have a head start to reach a potentially still-alive rhino and perhaps even the culprit.
Thornybush Game Reserve lies to the west of Kruger National Park. One of Africa’s largest game reserves at nearly 5 million acres, Kruger teems with wildlife, including more than 20,000 rhinos, and is a hotbed for poaching. Wedged against South Africa’s northeastern border, Kruger and nearby game reserves like Thornybush are particularly vulnerable. Poachers can easily escape into nearby Mozambique, where enforcement of wildlife poaching laws remains inconsistent.
Before his first trip to Africa last August, Bhatti had only seen rhinos on television and at the zoo. Half Syrian and half Pakistani, Bhatti was born in Pakistan and then grew up in London. He credits U.S. and European movies and TV shows for expanding his grasp of English. Wildlife shows on the National Geographic channel drew Bhatti in and inspired him to protect and defend endangered animals.
Witnessing the discovery, recovery and subsequent autopsy of the black rhino in Thornybush marked the first time Bhatti saw a rhino up close in the wild.
“Seeing the dead rhino was a devastating, cold-hearted reality,” Bhatti says. “It was surreal but it gave me new motivation for why my technology is relevant and why it’s important to get the product on the ground. If we could help catch one poacher, that would be a huge deterrent.”
Demand from Asia Drives Rhino Poaching
On the black market, rhino horns are worth more than gold — up to $100,000 for one kilogram of ground-up powder. Although global trade in rhino horn is banned by the Convention on International Trade in Endangered Species (CITES), skyrocketing demand in Asia since 2007 has led to unprecedented levels of poaching in South Africa. More than 8,000 rhinos have been slaughtered there in the last decade, mainly in and around Kruger National Park, including Thornybush Game Reserve, where engineering senior Saif Bhatti is testing his anti-poaching technology, Renoster.
Most poached rhino horns from Africa end up in China, where they are ground up, dissolved in liquid and used in traditional medicines. Rhino horns are made of keratin — the same substance in human fingernails and horse hooves. Although there is no evidence that keratin has any medicinal benefit, people have used rhino horns for 2,000 years for perceived treatments for many ailments, including hangovers, snakebites, headaches, cancer and impotence. In China and Vietnam rhino horns are also a status symbol and often used as ornaments, dagger handles and jewelry. — A.M.
Bhatti’s device uses signal processing to distinguish gunshots from other loud noises, such as thunder, branches breaking or elephants stampeding. To refine gunshot detection, Bhatti has worked closely with Stephen Tarzia ’09 MS, ’11 PhD, an assistant professor of computer science in the McCormick School of Engineering. An expert in acoustic sensing, Tarzia and his graduate students, Jiayue Sheng and Yuxing Guo, have helped Bhatti implement signal processing algorithms into his devices.
The basic challenge is to make a computer capable of listening for gunshots, Tarzia says. “The software must be simple enough to run on a cheap, solar-powered microprocessor but also sophisticated enough to distinguish between a gunshot and similar sounds.”
To train the device, Bhatti and his collaborators went to an outdoor shooting range. They recorded sounds from guns commonly used in poaching — including those with silencers.
The shooting range trials paid off. “In tests at Thornybush during the African winter, our device was able to detect a nonsuppressed weapon from 800 meters away and a suppressed weapon from 300 meters away,” Bhatti says. “Based on those estimates, we calculated that just 20 units could cover an area of 10,000 acres or so.”
Once a Renoster unit registers a gunshot, it sends relevant data to the cloud for trilateration, the process of determining locations by measurement of distances. Because cell service can be unreliable in the bush, Bhatti is focused on building a mesh network based on radio communication. For power, the device contains a battery that recharges with solar energy.
Africa has implemented other technological strategies to combat poaching, but none were specifically designed and built with poaching in mind, according to Bhatti.
“There are so many small intricacies and engineering challenges in the savanna,” Bhatti says. “It’s extremely hot with very little power supply and lots of dust. We wanted to make a purpose-built technology that takes those things into account.”
Tarzia credits Renoster’s innovative technology to Bhatti’s visionary thinking and collaborative approach.
“Saif has excelled at creating a vision for his project, forging partnerships and building prototypes,” Tarzia says. “My main role has been to slow him down when necessary to show him how to navigate the engineering product development steps that lead from that initial idea to successful deployment.”
Animated Infographic: How Renoster Works; Art: Matt Twombly
On the Front Lines
Conservationists and rangers have tried many methods to deter rhino poachers, with little success.
“The conservation of rhinos is not a simple issue,” says Martin Nieuwoudt, director of the Institute for Biomedical Engineering at Stellenbosch University in South Africa and one of Bhatti’s advisers. “It has turned into a literal war in the northeastern part of South Africa. Many conservation biologists, who got into science because of their love for ecosystems, are now soldiers in that war.”
Nieuwoudt has studied the radio tracking of rhinos, which is notoriously difficult. By continuously monitoring rhinos with an ankle bracelet, he says, experts could potentially learn more about rhino behaviors. This information could make rangers more proficient at protecting the world’s last rhinos and rebuilding their fading populations.
“This is difficult for many reasons,” Nieuwoudt says. “Rhinos have an incredibly thick hide and hate having anything attached to them. They will destroy those things.”
Rangers also have tried safely removing rhinos’ horns preemptively, hoping to remove the temptation to poachers. Tragically, this seemingly logical solution has not worked either. Poachers have continued to kill rhinos for the horns’ remaining, blunted stumps, because it is the heaviest — and thus most valuable — part of the horn.
Try, Try Again
Of course, Bhatti’s system also has faced its own challenges.
Last summer he mounted 15 Renoster units in trees across Thornybush. From there, he encountered multiple unanticipated engineering challenges. Everything from the types of trees to the heat to the rain disrupted his plans.
“I wanted to put the devices up in the trees to avoid interference from the deviations of sound on the ground,” he says. “But then I learned that elephants just like smashing trees. It’s a favorite hobby of theirs. I had to make sure to pick sturdy trees, like the marula.”
And then there was the weather.
During the summer rainy season, parts of South Africa receive heavy amounts of rain. A big challenge is to make the units porous enough to allow sound to enter them while ensuring that they remain water- and dust-proof. Bhatti first put boxes around the devices to waterproof them. The boxes, however, made the devices more susceptible to heat. “It turns out that when you put a device in a black box out in the summer sun, it’ll bake,” Bhatti laughs. For his next iteration, he used a special UV coating.
To help solve the waterproofing problem, Bhatti used Gore-Tex material to make a semipermeable acoustic vent that would prevent dust and water droplets from getting inside the device but still allow the microphones to pick up sound.
In late December, Bhatti returned to Thornybush Game Reserve to add the acoustic vents to his devices. He also collected data from the devices to see how well they processed and correctly identified sounds.
“When I first installed the devices, it was winter, so the bush was dead,” Bhatti says. “When I returned in the summer, the landscape was lush with greenery. The additional foliage really influences how sound dissipates away from a gunshot, so capturing that difference was important.”
Those working with Bhatti expect that he will press on until he perfects Renoster.
“Saif’s primary personality trait is persistence,” Niewoudt says. “He simply does not give up.”
Northwestern Network in Action
With its vulnerable rhino population and manageable size, Thornybush Game Reserve seemed like the natural place for Bhatti to field-test Renoster. And even better — Thornybush has a Northwestern connection.
Northwestern’s Global Learning Office (GLO) connected Bhatti with Nieuwoudt, the Stellenbosch University professor who directs the South African side of Northwestern’s Global Healthcare Technologies study abroad program. The GLO also helped put Bhatti in touch with alumnus David Bunn ’80 MA, ’87 PhD. After meeting with Bhatti in Evanston, Nieuwoudt later introduced him to Bunn, the former director of the Wits Knowledge Hub for Rural Development at the Wits Rural Facility, one of the largest and most prestigious rural research centers in Africa.
Bunn then connected Bhatti to the owner of a resort at Thornybush. Once this connection was made, Bhatti was off to the reserve to begin testing device prototypes. “This project almost didn’t happen because I couldn’t find any inroads,” Bhatti says. “But after Martin and I connected over our shared passion for animal conservation, everything changed.”
South Africa is home to 79% of Africa’s rhinos. Smaller numbers of rhinos live in Namibia, Kenya and Zimbabwe. Graphic: Matt Twombly
Protecting the Bush
This June, Bhatti graduates from Northwestern with a bachelor’s degree in industrial engineering and philosophy. But his journey with Renoster will not end with the Commencement ceremony. In addition to Gore-Tex, Bhatti has support from Thornybush, the Nature Conservancy, the Institute for Sustainability and Energy at Northwestern (ISEN) and the McCormick School to continue to develop his device.
Bhatti currently builds each device, one by one, in the lab. As soon as the prototypes are perfected, he will have enough funding from ISEN to enter a manufacturing stage. Professors at the Northwestern Pritzker School of Law also advised Bhatti on establishing Renoster as a private company, which will launch this summer.
Although developing the technology has been gratifying, Bhatti is motivated by the people he has met at the reserve and by the lifeless face of the lone rhino he saw on his first day at Thornybush.
“At the current rate of poaching, rhinos will be extinct within my lifetime,” he says. “People in South Africa are fighting to protect the bush on a daily basis. Just being able to help them in some way, that’s been the most rewarding.”
Amanda Morris ’14 MA is a science and engineering writer in Northwestern’s Office of Global Marketing and Communications.
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The photo of the rhino on the front cover is absolutely captivating — beautiful. I had no clue about the rhino poaching or its severity and extent.
—Wyetta Ballenger ’76 Lithia Springs, Ga., via Northwestern Magazine
I have always really enjoyed Northwestern, which I consider not just a good alumni publication but a good magazine, period.
So, in that spirit of appreciation, I have a query about the stunning back page photo from the spring 2020 edition connected to the heartbreaking story of rhino poaching. Why, when the story and the caption deal with South African rhinos, does the (presumptive) park ranger sport a Kenyan flag bracelet while tenderly touching near the closed eye of one rhino? Whatever the answer, the photo was a perfect accompaniment to the story, which I hope, with the help of Mr. Bhatti and other wonderful people, has a happy ending.
—Chris Doherty ’99 MBA, Baltimore, via Northwestern Magazine
Thanks for sharing the story about Sahif Bhatti and the innovative anti-poaching technologies he is bringing to sub-Saharan Africa.
I've worked in South Africa since 2007, and I'm always grateful when our alumni publications feature the important collaborative work happening between local stakeholders and well-intentioned alumni social entrepreneurs. However, I also read these pieces with a bit of trepidation. The concern stems from the tendency of US-based writers to lump all of sub-Saharan Africa into one "problem statement." Concommitantly, such profiles often erase the roles of local partners who are working day in and day out on the the challenges the "Alumni saviors" are addressing.
Bhatti's work is vitally important, inspired, and inspiring. And while poaching, as your story and graphics within the feature highlight, is a tragedy unfolding across many countries, the photo and snapshot stat on the back cover of the Spring 2020 magazine highlights the grave situation of rhinos in South Africa. Yet the bracelet worn by the person tending to the rhino is the Kenyan flag. And throughout the feature, only the Stellenbosch professor is named. None of the countless local workers on the frontlines of this fight is mentioned by name... or even passively acknowledged.
Please honor the on-the-ground heroes working to stop this horrific slaughter by at least attributing where they are, if not who they are.
—Brooke Wurst ’95 MS, Boston, via Northwestern Magazine
This was one of the best issues in recent memory. The feature articles were superb. I was especially taken with the “Rhino Rescue” story. Our alumni Southern Africa trip in 2018 included three days at Thornybush, where we were fortunate to see one of the white rhinos up close.
The poaching situation breaks our hearts. So pleased that one of our students has developed a tool in the fight against this terrible type of “hunting.” Kudos to him!
Congratulations on a fine job of keeping us alums apprised of the fabulous work of our students and faculty.
—Bob Seal ’71 McKinney, Texas, via Northwestern Magazine
Saif, I am so incredibly impressed with you and grateful to you for your work to save the rhinos.
Job well done, sir, job well done.
—Scott S. Pope Raleigh, N.C., via Northwestern Magazine
Thank you. This is incredible work for rhinos! How can we make an outright donation to support Bhatti's particular project?
—Katy Fendrich-Turner and Chad Turner ’97 Austin, Texas, via Northwestern Magazine