In July 2026, the Endangered Wildlife Trust joined conservationists and researchers worldwide in mourning the death of Dr Gus Mills, a renowned Brown Hyaena, Cheetah and African Wild Dog specialist, and author.

Gus left an indelible mark on carnivore conservation in South Africa, and through a variety of international bodies on which he shared his expertise about nature’s apex predators, including canids and big cats.  This included serving as a senior member of the IUCN Carnivore Specialist Groups. He was a former chair of the Hyaena Specialist Group and member of the steering committees of the Cat Specialist Group and the Canid Specialist Group.  Gus was the founder of the Endangered Wildlife Trust’s Carnivore Conservation Group.

Gus’s first introduction to the EWT was when he undertook research in the Kalahari into Brown Hyaena in 1973, the year the EWT was established by South African conservationist and artist, Clive Walker, James Clarke and Neville Anderson. A year later, the EWT funded some equipment for the project run by the then MSc student at the University of Pretoria. This was the EWT’s third sponsorship.

Describing Gus as a “wonderful human being”, Clive Walker, founder of the EWT, said: “He was second researcher the EWT invested in back in the 1970’s and one of the finest who devoted his life to conservation”.

Gus continued his research about Brown Hyaenas and Spotted Hyaenas for 15 years, publishing Kalahari Hyenas: the comparative behavioural ecology of two species in 1990.

In 1996, he was asked by the then Director of the EWT, Dr John Ledger, to form the EWT’s Carnivore Conservation Group. This was achieved through a partnership with SANParks which allowed him to work full-time on carnivores while establishing and running the EWT’s Carnivore Conservation Group and working for SANParks. Funding for this unique arrangement was provided by the Lewis Foundation.

The EWT’s Carnivore Conservation Unit is today recognised as a leader in lion population research, the metapopulation management of Cheetah and African Wild Dog throughout southern Africa, and addressing threats to carnivores through human-wildlife conflict and the illegal wildlife trade.

During his time at SANParks, Gus researched Cheetah, African Wild Dog, Honey Badgers, Brown Hyena, and lions. He introduced the concept of metapopulation management of wild dogs and with the assistance of the late Pat Fletcher, pulled together numerous agencies and landowners to achieve genetic management of scattered populations through the Wild Dog Advisory Group.

Derek van der Merwe, manager of the EWT’s Carnivore Conservation Unit, said: “It is remarkable to reflect on how much has changed since those early days, when Gus would fly over the Kruger National Park in a small EWT aircraft equipped with telemetry equipment, tracking African wild dogs from the air. Those pioneering efforts helped establish many of the approaches that underpin carnivore conservation today”.

Cole du Plessis, project manager in the Carnivore Conservation Unit said: “Long before GPS collars and big datasets, there were people like Gus patiently building our understanding of Africa’s carnivores, one observation at a time.  He was also ahead of his time. He encouraged visitors to Kruger National Park to photograph wild dogs and cheetahs because every individual has a unique coat pattern. Those photographs became one of South Africa’s earliest citizen science programmes, and remarkably, that project still contributes to carnivore conservation today”.

Cole believes what made Gus so remarkable was that he fundamentally changed the way we understand Africa’s carnivores. “He wasn’t simply observing animals – he was curious. He spent decades asking and answering the questions that have shaped how we understand Africa’s carnivores today”.

“His work on lions, cheetahs, hyaenas and African wild dogs laid much of the scientific foundation that modern carnivore conservation is built upon. But perhaps just as importantly, Gus had an incredible ability to connect science with the natural world. He showed that good science and a deep appreciation for nature could go hand in hand.”  said Cole who believes his greatest impact was how Gus did his science.

 “I actually think that may be his greatest legacy. Scientific papers are incredibly important, but they only go so far. Gus invested in people. He mentored students, encouraged young researchers, and inspired countless conservationists through his generosity, humility and willingness to share his knowledge. If you look across Africa today, many of the people leading carnivore conservation were either directly mentored by Gus or influenced by his research. His legacy isn’t just in the knowledge he created—it’s in the people who continue that work every single day”  said Cole.

Gus retired from SANParks in 2006 after 40 years of service.  Based in the Kalahari, with his wife, Margie, Gus then embarked on a study of Cheetah that saw the publication of A Natural History Guide to the Arid Kalahari in 2014,  four years after the release of what remains one of his most memorable books Hyena Nights and Kalahari Days.  This book continues to raise awareness about this often misunderstood species.

“Gus was an excellent public speaker and presenter. His talks to EWT members at the Johannesburg Country Club were always ‘full-house’ occasions. His charming personality drew people towards him and his passion for carnivore conservation was admired by many EWT supporters. Some of the latter, like Stuart Bromfield and Norman Stein became generous donors to EWT carnivore projects,”  said John Ledger.

Derek described Gus as a quiet, yet immensely influential presence in conservation.

“There are few people whose authenticity, humility, and dedication matched his. His writings, particularly Cry of the Kalahari, captured not only the science of conservation, but also the wonder and privilege of sharing the landscape with Africa’s wildlife. His contributions to the conservation of lions, Cheetahs, African Wild Dogs, and hyaenas extended far beyond the EWT, influencing generations of researchers and practitioners around the world,” he said.

“For those of us who now have the privilege of carrying this work forward, we do so standing on the shoulders of pioneers like Gus. His legacy lives on not only through his extraordinary scientific contributions, but through the countless people he inspired and the conservation programmes he helped set in motion,”  said Derek.

Yolan Friedmann, CEO of the EWT, described the immense influence Gus had on her career.

“I had the privilege of getting into the field with Gus as an early-stage career conservationist, and to watch with wonder how he tracked Wild Dogs; I remember with fondness bumping around in the back of bakkies as we tore after these extraordinary carnivores in pursuit of their pray. Gus instilled in me a love for Wild Dogs and I worked with Gus to develop the first project to develop a sustainable Wild Dog population outside of the Kruger National Park through range expansion into KwaZulu-Natal, in the early 2000s. I loved our debates about the philosophical lines between animal welfare and conservation and the role of the individual versus the population. Gus taught me so much and made a lasting impression on my conservation career. His legend will live on in the lives he touched wherever he went,” she said.

Gus will be remembered as was a dedicated conservationist who believed that the youth and local communities had an important role to play in the future of all species. His mark on conservation will always be remembered. His wife Margie worked alongside Gus in the field in the Kalahari, enduring hardships in remote areas and contributing to their joint books in a remarkable partnership that endured for more than half a century. We share the grief of losing of this special man with Margie, their biologist son Michael, daughter Debbie and the grandchildren.