In 1992 the Academy of Natural Sciences in Philadelphia, Pennsylvania, presented Cooper with its gold medal for "artistic endeavors and life's work which have contributed to mankind's better understanding and appreciation of living things".
Preferring to draw from life, rather than depending on photographs as the main source of material for his work, he would often venture into wild, untamed parts of the world to capture the exact display of the birds he painted.
He lived with his wife, Wendy Cooper, a self-taught botanist who has authored four substantial books, in north Queensland where his studio was surrounded by tropical rainforest.
Sir David Attenborough described Cooper as "Australia's greatest living scientific painter of birds; he is possibly the best in the world".
A biography, An Eye For Nature — The Life and Art of William T. Cooper, written by Penny Olsen and published by The National Library of Australia, was launched in February 2014.