Hong Kong's Borneo orang-utan twins turned one last week, and are starting to connect with their mother. But they are still far from being intimate.
The pair, a male and a female, born on July 8 last year at the Hong Kong Zoological and Botanical Gardens, were rejected by their mother Raba for several months.
Raba, a 16-year-old also born in Hong Kong, used to just ignore her babies and stay up in the metal rafters of her cage - a place her kids still cannot reach.
'Now, Raba is more comfortable being around her children', said the zoo's deputy manager, Wilson Ng Kwok-foo. 'She sometimes sniffs them and touches them gently - yet they are far from being very close.'
The male and female - named Wan Wan and Wah Wah, respectively - weighed 2kg and 1.4kg respectively at birth. They are now about four times that weight.
Their usual diet includes fruit, especially bananas, and human baby food, according to Lai Yuk-ming, senior amenities assistant, who takes care of them.
'They are usually more relaxed, but are a bit nervous now, because you guys are here,' Lai said, referring to the presence of a reporter and photographer from the Sunday Morning Post.
'While they are staying very quiet now, they are observing you both. Human babies would do the same,' he said.
But one difference from human babies is the amount of time the apes spend with their parents: only about 15 to 20 minutes a week.
'We need to let them spend more time together gradually,' Ng said. 'We are unsure how Raba would react to them. We're afraid she may hurt them, perhaps by dropping them from a high bar.
'Now their arms are becoming stronger, but they still cannot balance well.'
When they can balance well, they will be put in bigger cages. That would be at least a year or two from now, Ng said.
A veterinarian has said it could take years for Raba to fully accept her twins. If she shows any real interest, the zookeepers will help forge deeper family ties.
For the first seven months after their births, they were taken care of by human hands indoors while their mother lived in a separate enclosure outside - a move that animal-rights groups questioned.
Mara McCaffery, founder of Orang-utan Aid Hong Kong, said she was not surprised little headway had been made in reuniting the babies with their mother, based on the amount of time they spent near each other.
'Fifteen minutes once a week is a completely inadequate attempt at achieving this,' she said. 'If Raba is showing any interest at all, this should be capitalised on immediately, with constant visual contact every day.'
She said it was very uncommon for orang-utans in the wild to reject their infants, though she added that this seemed to be 'something which happens rather more frequently with captive or captive-born orang-utans'.
She said that at Houston Zoo, 50 volunteers assisted in caring for a baby orang-utan for about 10 months, but while it was in the company of the other orang-utans.
'This way, both the adults and the babies could get used to each other. It was a surrogate mother that finally accepted the infant,' she said.
'My question to the zoo is: have they considered the fact that if Raba rejected her babies once, she may not accept them at all? Since they have another female in the exhibit, should they not be considering her as a possible surrogate mother?'
Either way, unless the zoo drastically increased the amount of time the family spent together, McCaffery 'cannot see any scenario being successful'.
Orang-utan babies should be with their mother or surrogate for at least the first seven years of their life, she said. This was not only so the mother could teach them to survive, but also to guide their social and emotional development 'as a human mother would'.
'Just because they are strong enough to climb and balance unaided does not mean that they can simply be put into a larger cage without the guidance of a mother. I feel that a much more urgent effort should be made to try and reunite the mother and babies,' she said.
Orang-utans are one of the most endangered species on the planet, and live only on Borneo and Sumatra in Indonesia.
Endangered species such as the Borneo orang-utans are kept at the zoo for conservation and education purposes, but McCaffery questioned the logic of that.
'I find it strange that they have not produced more comprehensive information about the dangers which threaten the survival of orang-utans in the wild. So much more can be done.'