In September this year Matang received two infant silver leaf monkeys, or silver langurs, that had been surrendered from illegal pet trade. This is not a common species that we receive at Matang, probably because this leaf-eating monkey is incredibly difficult to successfully wean in isolation from con-specifics. To digest their adult diet of leaves, this monkey’s multi-chambered stomach needs specialised bacteria to take care of the job. It is thought that these bacteria are obtained through contact with the faeces and saliva of other adults in the group – you can see how this poses challenges for successful rearing of monkeys orphaned through illegal trade. Unfortunately the first infant that was surrendered to us died within the first week of her arrival to Matang, but the second infant was in much better condition – we suspect he was a few weeks younger and therefore not yet struggling with the weaning process.
Silver langurs live in troops with multiple females to only one male. These monkeys display ‘allomothering’, which means the job of mum is undertaken by all females in the troop. From the day a new langur is born, all females in the troop will happily handle and care for it. The infants of this species are born bright orange in colour, which is a striking contrast to the silvery-grey colour of the adults. It is thought that one of the reasons for this is so that dependent infants are easily identifiable, and extra endearing, to all females in the troop, and marks them as the monkeys that everyone needs to care and look out for.
The allomothering behaviour of this species made it tempting for us to consider release of the surviving infant to the wild in the hope that an existing troop of langurs would be only too pleased to look after an unrelated infant due to the strong instinct to protect and care for young. However, another behavioural feature of this species gave us pause – when a new dominant male takes over a troop of females, he engages in infanticide and kills all existing infants to ensure propagation of his own genetic material above another male’s. It is not known whether this instinct would kick in if an unrelated infant was introduced into an existing wild troop, but it is quite a significant risk to take.
Also, when considering release of an ex-captive animal to the wild, conservation of the wild population and ecosystem must always be of paramount importance, to be held in much higher regard than the simple potential happiness of one individual orphan in human care. Reintroduction of an ex-captive animal poses many risks to the established ecosystem and wild conspecifics, and should only be considered if the possible conservation benefit of releasing that individual outweighs these potential risks. For a full discussion of these issues and points for consideration, please have a read of the IUCN Guidelines for the Placement of Confiscated Animals – these are not issues to be taken lightly, and effectively argue against the release of ex-captives in the vast majority of cases. This is a rather disappointing reality to be faced with, especially when the majority of documentaries tend to focus on the one-in-a-hundred case where release may be both viable and, at least on the surface, successful.
If release is the chosen course, post-release monitoring should be a standard course of action. To simply put animals back in the jungle and assume they live happily ever after is irresponsible. If an animal has been in human care for a number of weeks or months, it is highly unlikely that the wild is going to be an appealing place for them, and hard release is most likely condemning that animal to death by starvation – not quite a happily-ever-after end to their story.
While thinking about the best course of action for the little langur in our care, and striving to bring him successfully through the weaning process, we set off to Bako National Park to attempt a week-long follow of the wild troops of langurs, to at least gain an idea as to whether post-release monitoring of this species would be feasible. Though we were able to observe many hours of wild langur behaviour and learn a lot about them, we were also able to determine that continuous, 24-hour monitoring of the troop would be pretty much impossible. However, we were able to collect samples of wild langur faeces, which we brought back to Matang to make delicious poo-milk, and poo-and-vegetable smoothies for the orphaned infant. This, we hoped, would assist the development of the correct gut flora for his adult leafy diet.
Three months on and this little orphan is doing incredibly well. We have had some rough weeks where we thought he might not pull through, but for now he is certainly on top, eating a good mixture of milk and vegetables and is in excellent health. We have turned our spare room/store room/nursery into a jungle gym, and the langur is quite happy letting himself out of his cage to play around in the trees in between feeds. His future is still uncertain, but we’re very satisfied to have kept him happy and healthy up to now. It’s been a tough road! But well worth the efforts.
In all honesty, the reason for seriously considering release of this orphan was our certainty that he would not survive being hand-raised in isolation from other langurs, due to our past experience and other information we had read. Though there would have been no scientific support for this, and it certainly would not have been an action in accordance with the IUCN guidelines, sometimes the decisions we are faced with when working on the ground, being responsible for the lives of these individuals that end up in our care (through no fault, nor choice, of their own) are not easy, nor made with the black-and-white manual of academic bodies as the only rule book. It is very easy to read all the recommendations and think about what should be done – however when you are holding these vulnerable animals with the knowledge that their whole existence depends on you and the decisions you make, it is not so easy.
We will keep you posted on the progress of this little monkey.