Koko the sign-language speaking gorilla has adopted two kittens

'It has energized her world'

Koko the gorilla places Ms Gray the kitten on top of her head

Koko, the gorilla famous for her ability to communicate using sign language, now has the family she always wanted.

On her 44th birthday, the childless Koko was given a box full of kittens by trainer Francine Patterson and immediately fell in love with the tiny felines — and they fell for her in kind.

According The Gorilla Foundation, Koko has been saying for years how much she wants children, often signing the word ‘baby’ and playing with toy dolls as though they were her own.

Upon meeting the litter of kittens, Koko signed ‘cat’ and ‘baby’ — apparently informing her handlers that these are now her children.

The beautiful introduction has been captured on film and posted to YouTube by the foundation’s ‘kokoflix’ account.

Koko is shown to be careful and patient with the kittens, allowing the little creatures time to get to know her and only delicately lifting one up after they had been effectively introduced.

In a particularly charming part of the video, Koko requests that the kitten known as ‘Ms Gray’ be placed on her head.

Meanwhile another kitten - ‘Ms Black’ - is caught trying to claw her way out of an animal bag in the hopes of playing with the gentle giant.

The text that appears in the video reads: “Koko fell in love with one, and the other fell in love with her. Koko has adopted these two kittens into her family, and it has energized her world.

“Not only have Koko's maternal and play instincts kicked in, but she is signing more to her caregivers and generating new content every day that can be used by The Gorilla Foundation to create empathy for great apes.”

Koko, who was born at San Francisco Zoo and raised at The Gorilla Foundation in nearby town Woodside, is able to understand more than 1,000 signs of what Patterson calls 'Gorilla Sign Language' and can make sense of around 2,000 words of spoken English.

Though she spent a lot of time with two male gorillas, Koko did not mate with either, forming a 'sibling relationship' with one - who died in 2000 - and getting along well with the other.

Introducing other female gorillas into the family has reportedly failed.

But now Koko has kittens, after asking for one for more than 30 years.