Renowned wildlife illustrator William T. Cooper was once described by Sir David Attenborough as the best ornithological illustrator alive.

The artist, known to his friends as Bill, was even the subject of one of Sir David's films, Portrait Painter to the Birds.

Mr Cooper, 81, died at his home at Malanda, south-west of Cairns, in far north Queensland on Sunday afternoon.

In a career stretching back to the early 1960s, Mr Cooper illustrated numerous books, including Portfolio of Australian Birds, Parrots of the World, Birds of Paradise and Bowerbirds.

All the books were authored by Canberra ornithologist Joseph Forshaw, with whom Mr Cooper partnered for more than 40 years.

Mr Cooper's paintings and illustrations have hung in galleries around the world.

William Cooper said he always "fiddling around" drawing birds when he was a child. ( Supplied: CSIRO Publishing )

In 1994, he received an Order of Australia for his contribution to art and natural history.

Known for his extreme attention to detail, Mr Cooper spoke with the ABC about his technique last year.

"The relationship with the bill, to the eye, to the head size, they all go to give that bird the right look," he said.

"If you can catch the expression of the bird, then you've got the gist.

"As a child, I always had an interest in wildlife, natural history and I was always fiddling around drawing birds.

A 1971 painting of a night parrot by William Cooper. ( Supplied: National Library of Australia )

"There was no opening to work professionally in bird painting in the early years but then gradually an interest arose in the public in wildlife."

Last year, Mr Cooper's biographer Penny Olsen told the ABC's Radio National that Mr Cooper's father taught him the wonders of the bush, while his mother encouraged his interests in bird books and drawing.

"Finding his niche as a natural history painter provided Bill with an entree into a life of adventure, exploration, discovery and unique experiences," she said.

"All along his journey, he has met exceptional individuals, experts, dignitaries and people living extraordinary lives.

"He's travelled through India, East Africa, Japan, Indonesia, Malaysia and, of course, Australia, in search of birds."

She said last year, at the age of 80, he was still working six hours a day.

Mr Cooper died at home following a long illness.