Heartwarming moment gorilla gently cuddles kittens
Koko, who has no babies of her own, told her trainers in Woodside Hills, California, that she wanted a cat to celebrate her 44th birthday.
As soon as she saw the kittens, the gentle giant gently put her hand into their box to let them sniff her.
Heart-warmingly, she scooped one of them up and played with it.
Although her hands are big and strong enough to crush the small creatures, she handled them delicately.
Incredible Koko then told her trainer Francine Patterson that the kittens were now her babies.
The Gorilla Foundation released the video of the moving introduction on YouTube.
She had been trained in a gorilla version of American Sign Language since she was born, and can also understand 2,000 spoken words.
Alongside the video, uploaded by the account kokoflix, it said: "Koko got her birthday wish this July 4th - not only did one kitten come to visit, but a whole litter.
"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 energised 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."
The remarkable creature was also great pals with actor Robin Williams. After his death in August 2014, her trainer used sign language to explain what had happened. In another emotional video, Koko is filmed looking sad after receiving the devastating news.
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