10 Dec 2013

Subis and Emma are Chester’s adult female Sumatran orangutans. They are sisters, both born here at Chester and the offspring of our original pair of Sumatran orangutans Oscar & Ramona. Ramona was sadly lacking in her maternal behaviours and once she had given birth took no interest in rearing the young herself.

Subis was born in 1986 and Emma, 15 months later, in 1987. Reared by keepers at the zoo during the daytime, they were both taken home by their respective keepers to be looked after around the clock. Once Subis was returned to the zoo on a full time basis it meant that Emma, although younger, could be brought back into the zoo full time a lot sooner than Subis, as they could ‘buddy up’.


Sumatran orangutan with baby
Subis and baby


This system is common at rehabilitation centres in Borneo and Sumatra. Rather than the youngsters bonding to human carers which can lead to problems once they reach adulthood, they can bond to fellow orangutans. This replaces the emotional bond usually filled between mother and baby.

For the ensuing years they lived together more than amicably, never wanting to be separated from each other. As a youngster Subis had an unfortunate incident when keepers tried to reintroduce her to the older orangutans. Her father Oscar bit her arm and hand which resulted in her losing her middle digit. This healed up quickly and it doesn’t hinder her in the slightest but it is one way that visitors can distinguish who is who between her and Emma. Further efforts to reintroduce were scrapped due to the risk of further injury.

In the early nineties Oscar and Ramona left the collection to go to other zoos in Europe, which made space for Puluh in 1996. All three animals were of a similar age, and young enough to engage in lots of play behaviours, but of the three at that time, Subis was most dominant. It’s hard to recall that time these days, as the group dynamic has shifted so much.

When I first started on the Primate Section in 1998, both Subis and Emma had had pregnancy tests that were positive. It was exciting to have imminent births, not only from a critically endangered species but the first Sumatran orangutan births at Chester since Subis and Emma themselves more than ten years previous. Fully aware of what can happen with hand-reared orangutan females, we desperately wanted to break the cycle of human reared orangutans that grow up with no maternal knowledge and when they themselves give birth do not know what to do.

Sumatran orangutan Emma and baby at Chester Zoo
Emma and baby


Various options were discussed, such as showing them videos of orangutans giving birth and infants suckling, training to hold a doll, if it was an option we considered it. The option we went for that actually achieved success was introducing them to their Bornean neighbours who they had previously always been kept separate from.

Bornean orangutans and Sumatran orangutans will produce hybrid offspring, so the two species are always kept apart. At that time we had a Sumatran area with the corresponding signage and the same for the Borneans. With a part of the keepers morning spent juggling the animals about between areas, we were able to leave Puluh on his own every alternate day and introduced Subis and Emma to our Bornean females Martha and Sarikei.

Both Bornean females had infants, aged two and three which occasionally still suckled from their mothers. Marthas infant ‘Leia’ was quite reserved, but Sarikei’s infant ‘Matu’ was a confident little soul. I can remember opening a slide to give the four females and two infants access to one another in neighbouring day yards. Subis and Emma stayed put in their yard, Martha and Sarikei stayed put in their yard. Leia stayed with her mother but little Matu went through to join Subis and Emma.

He trundled up to them to investigate the potential new play mates. Fearful that Matu’s confidence would be his undoing (e.g if Subis or Emma became aggressive towards him without Sarikei at arm’s reach to come to his rescue) it was amusing to see the complete opposite reaction. Subis and Emma’s main reaction seemed to be ‘What is that?’ Confronted by a quickly advancing strange ‘pygmy’ orangutan they retreated in shock! Over the next few weeks all the individuals became fairly relaxed around one another and it was both a surprise and encouraging to find Subis cuddling Matu one day.

Subis and Bundi - orangutans at Chester Zoo
Subis and Bundi


A couple of months later Subis gave birth to a female infant we named Jambi. Her maternal instincts kicked in and we breathed a sigh of relief. Subis was a little rough with Jambi, plucking her on and off her chest and after a couple of months began a behaviour which was even less positive. It seemed that at times Subis got bored of having the infant in tow and would set her down, and occupy her time doing other things other than playing mother.

It was worrying that she was doing this but Jambi continued to grow with no detriment to her welfare. Aside from the incident I described earlier in the blog about Puluh another memorable incident occured during this time. When people ask me ‘How intelligent is an orangutan’ this is one of the examples I give as to their thought process. At this point in time Emma (who was still pregnant) was very much dominated by Subis and if she tried to interact with an abandoned Jambi, she had to beat a hasty retreat as Subis came back to collect her daughter.

On one occasion I happened to be checking on the orangutans during the day and reached the Sumatran Orangutan yard to see Emma with Subis & Jambi sat on the platform in the yard. Subis plucked the baby from her chest and set her down on the platform as she went for ‘a break’ at the other end of the climbing frame.

Emma was now well aware to leave the baby alone or feel Subis’s wrath so sat quietly staring at me, but obviously had Jambi in view from the corner of her eye. Jambi was now able to slowly crawl and move herself, and a wave of sickness hit me as the baby crawled closer to the edge of the platform. There was a thin substrate on top of a concrete floor but if she fell off she could badly injure herself.

Before I could call Subis, in an effort to get her attention and get her to come to Jambi’s rescue, Emma intervened. She quickly looked behind her, checked that Subis wasn’t looking in her and Jambi’s direction, then shot out an arm, grabbed Jambi and slid her back to the centre of the platform. She then let her go and carried on sitting as she had been, apparently paying no attention to the youngster.

Baby Orangutan at Chester Zoo
Emma and baby


I interpreted the chain of events as Emma weighing up the situation that the baby was in danger, whilst simultaneously not wanting a confrontation with Subis for intervening. Clever Emma! When Emma gave birth later in the year she became protective to her own baby and no longer let Subis rule the roost. By this stage she had in fact become a more solidly built orangutan than Subis. These days it is now Subis that gets out of Emma’s way! With each successive birth Subis and Emma’s mothering skills have improved immensely and certainly after their respective third infants have now become perfect mothers.

In 2007 all the Sumatran orangutan group were moved over to the new Realm Of The Red Ape exhibit, and aside from a very cautious Puluh, the rest of the group were clambering all over the place in no time. We thought that the infants would stay close to Subis and Emma but the new exhibit just seemed to herald ‘playtime’. One thing we didn’t foresee in the planning process was Subis and Emma’s desire to take a closer look at the visitors.

To protect the windows from damage and to stop the orangutans dirtying them they were designed so the orangutans couldn’t sit directly at the glass. Emma and Subis proved their inventiveness by taking free hanging pieces of strapping and threading them through the mesh adjacent to the windows. By tying the strapping they form makeshift hammocks and recline in relative comfort (if you’re an orangutan) to get a good view of the visitors that pass through the building.

The exhibit and the husbandry we practice in Realm Of The Red Ape (RORA) seems to encourage independence, allowing the infants much more scope to move around and interact with the other orangutans (and gibbons) than in the old building. All the infants born and raised since moving to RORA are what I would call nice, steady, confident individuals. Similar husbandry will be adopted when our Sumatran group move to a new building upon the completion of ‘Islands’ and it will be interesting to see them explore their new home and settle in.

As I approach the end of this blog I think it’s apt that all the offspring from Puluh, Subis and Emma get a mention. Jambi born to Subis in September 1998 went to Budapest Zoo in 2007 and now has a daughter herself, born in 2010 named Moira. Padang born to Emma in November 1998 went to Prague in 2010 and he sired ‘Diri’ born early in 2013. Utara born to Emma in March 2004 is still with us, but plans are in motion for her to be relocated to another zoo. Budi born to Subis in June 2004 went to Basel in 2012. Kirana born to Subis in February 2009, Indah born to Emma in February 2008, Tripa born to Emma in October 2012 and Tuti born to Subis in December 2012 are all growing up nicely.

Each orangutan is very much an individual, and their characters blossom as they grow and watching them develop is one of the best parts of the job.

I’m Chris Yarwood and I Act for Wildlife.