Save the Elephants said in a statement that Douglas-Hamilton passed away in Nairobi late Monday, calling him a "pioneering force" in elephant conservation, who "revolutionised our understanding... through his groundbreaking research".

"His work laid the foundation for modern elephant behavioural studies and conservation practices," it said.

The Scottish zoologist was born and educated in the United Kingdom, but spent much of his life in Africa, working in Uganda and Tanzania before settling with his family in Kenya.

"Iain changed the future not just for elephants, but for huge numbers of people across the globe. His courage, determination and rigour inspired everyone he met," said Frank Pope, Save the Elephants CEO.

"He never lost his lifelong curiosity with what was happening inside the minds of one of our planet's most intriguing creatures," Pope said.

Douglas-Hamilton began his work researching elephants in Tanzania before turning to pachyderm protection in the 1980s during an ivory poaching crisis.

His work documenting the scale of the crisis, using aerial monitoring to count large populations for the first time, helped gather momentum around the intergovernmental push to ban the global ivory trade in 1989.

The work was not without risk. He and his wife would sit on flak jackets in their small plane to avoid poachers' bullets.

Douglas-Hamilton, who established Save the Elephants in 1993, was also among the first to introduce GPS tracking and aerial survey techniques, with his methods now considered standard practice in wildlife conservation.

He and his wife, Oria, published two award-winning books about elephants, and he was recognised with an Order of the British Empire (OBE) in 1992 and a Commander of the British Empire (CBE) in 2015.