Gladys the gorilla raised by surrogates celebrates her first birthday with special cake made of rice and veg

Surrogate project at Cincinnati Zoo hailed a success 

Gladys was raised by keepers at Cincinnati Zoo for five months before being introduced to other gorillas

A baby gorilla raised by human surrogates who dressed in furry vests to mimic primates has celebrated her first birthday at an Ohio zoo.

The celebration for Gladys, who tucked into a rice and vegetable cake with sweet potato and banana frosting, marked a key milestone for the primate who has now been accepted by the zoo's other gorillas.

As Cincinnati Zoo keepers laid out her birthday cake this week, it was the gorilla's surrogate mom, M'Linzi, that led the still small Gladys to her treat. 

First birthday: Gladys sticks close to her surrogate mother M'Linzi as she tucks into her cake

Growing up: Gladys is learning to live with other gorillas after being hand reared

Adorable footage showed the tiny creature tentatively chewing on a piece of fruit before leaning in to grab a huge mouthful of cake, smearing its puree frosting across her face.

Seeing Gladys enjoy her cake in the company of other gorillas was a proud moment for the Cincinnati keepers, who had acted as surrogates to her for five months

When she was transferred to the zoo at the age of four weeks, after being rejected by her mother, staff worked in shifts to provide round-the-clock care.

As well as tending to her basic feeding and cleaning needs, keepers had to teach Gladys how to be a gorilla. 

They wore specially made furry vests, walked on their hands and knees while the baby gorilla clung to them, and tried to teach her the low grunting sounds made by her species.

At five months old, Gladys was ready to be introduced to the zoo's main gorilla group, and she was paired up with 31-year-old M'Linzi.

Birthday treat: M'Linzi, who has been looking after Gladys since June, is the first one to sample the cake

Dig in: Gladys leans in for a mouthful of the rice and fruit cake that had banana and sweet potato frosting

Bond: M'Linzi cuddles up to Gladys as they share the gorilla's birthday cake

Primate curator Ron Evans said helping to raise Gladys had been 'unlike anything I have experienced in my 30 years here'.

'It was the best experience of my life and something I hope we never have to do again.'

The success with Gladys is expected to help other zoos. The zoo has made 29 videos of her development for its YouTube channel.

A compilation video will be shared, said Dusty Lombardi, an animal care specialist in Columbus.

'We watched those. They were terrific,' said Roseann Giambro, primate keeper at the Pittsburgh Zoo & PPG Aquarium, where keepers hand-raised a baby gorilla for four months last year.

Cincinnati Zoo has asked fans of young Gladys to send in old cell phones as part of its Project Saving Species fund-raising campaign.

Being mom: Ron Evans carries a three-month-old Gladys around her enclosure on his back

Go ape: Ashley Chance wears a furry vest as she walks with Gladys on her back

Nap time: Ron Evans catches up with paperwork as his young charge sleeps