Dr Michael "Gus" Mills, one of Africa's most respected carnivore scientists and one of the great field naturalists of his generation, died on 12 July after suffering from cancer. His death removes from the continent a rare combination of rigorous scientist, patient observer, practical conservationist and gifted storyteller.

For more than half a century, Michael "Gus" Mills followed predators across the red dunes of the Kalahari and through the savanna of Kruger National Park. He studied hyenas, lions, cheetahs and African wild dogs, but his true subject was larger than any single species.

He wanted to understand how predators, prey, landscape and climate fitted together and how conservation could protect those relationships without turning wild places into controlled outdoor zoos.

It was an unlikely career. Mills described himself as a poor student who initially failed matric and later stumbled through psychology. The decisive moment had come earlier, on his first visit to Kruger in 1954, when he was eight. The experience changed him.

After completing a BSc at the University of Cape Town and an Honours degree in wildlife management at the University of Pretoria, he secured a position researching brown hyenas in the Kalahari. In 1972, he and his newly married wife, Margie, headed into the desert. What was supposed to be a two-year assignment became 12 years.

For their first years, the couple lived in a tent and small caravan beneath a camelthorn tree, enduring furnace-like summers, freezing winter nights, dust storms and large...