Koko, the western lowland gorilla who gained worldwide fame for her mastery of sign language, has died at the age of 46. She died in her sleep at The Gorilla Foundation preserve in California's Santa Cruz mountains on Tuesday.

Born in 1971 at San Francisco Zoo, Dr Francine “Penny” Patterson famously began teaching Koko sign language from an early age.

Koko learnt more than 1,000 signs, according to Patterson, and became part of a Stanford University project in 1974, inspiring the formation of The Gorilla Foundation.

The foundation paid tribute to Koko by praising the influence she had as a “primary ambassador for her endangered species”.

“Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy. She was beloved and will be deeply missed,” the foundation said.