Just so story #4 ; Young mammal offspring and mysteries of life and death within Forests

How many species – that are right in front of us – don’t we see? 
As an OuTrop researcher, here I find out a little bit more about a species that 99% of us will never see!… 

Balantidium coli

We have no idea of how many species lurk deep in the forest. Even though we are in the forest every day, there will be hundreds of species of fungus, insects and many species of plants and even mammals we don’t know about. Only estimates can be made for the numbers of species – especially difficult to gauge in biodiverse areas (for example in some tropical forests can contain as many as 1,500 flowering plants, 750 species of trees, 400 species of birds and 150 species of butterflies in a typical four-square-mile patch(1))…


Recently our researchers have been finding out about the parasite Balantidium coli. It is a ciliate protozoan, so within the ciliate phylum of the animal kingdom. It’s no surprise we don’t see this species as…
a) it is an internal parasite of mammals, and
b) it is only between 40 µm to 200 µm in size(2)… (we are yet to get a good enough microscope set up in the middle of the jungle!)

It causes the disease Balantidiasis(3). Balantidium coli is found throughout the world and lives inside mammals. Pigs are used as reservoir hosts(4), throughout of a total of 56 mammalian species, the parasite was found in 6 species, all belonging to the orders Primates and even-toed ungulates (Artiodactyla)(5). New hosts now include the white-handed gibbon (Hylobates lar), squirrel monkey (Saimiri sciurea) and Japanese macaque (Macaca fuscata)(5), none of which are found in Sabangau. It is the only member of the ciliate phylum known to be pathogenic to humans(3). There have been no reports of resistance to treatment, but as might be expected, the warming of the earth’s surface may provide increasing areas of favourable environment for the parasite and the survival of trophic and cystic stages of Balantidium, along with its prevalence, may increase(4).


The reason our scientists have been researching this tiny species, is that in the past three months we have recorded two primate deaths. A one year old male gibbon, ‘Mr Miyagi’ of Karate, was recorded as dead in December and Indah’s three month old baby orangutan was recorded dead this past month. Both these looses are incredibly sad, but due to the young age of the individuals there is no way these babies could survive when separated from their mothers. Missing individuals like these are how primatologists record the majority of confirmed young primate deaths.

Here is one of the few photos of Indah’s young baby before it died. We never knew the sex of the offspring. Photo ©Jess Stitt.

Although emotional for our scientists whom have come to know these individuals, the science behind these natural deaths – intricacies of primate life in Sabangau – is very interesting.

We have also seen both Chun, Mr Miyagi’s mother, and Coklat, the female of another gibbon group, vomiting on one or two occasions. This means there has been at least a small problem in two different gibbon groups. There are, however, many reasons why these young primates could of died. The actual occurrence of death has not been observed and any poo samples that may show the presence of the parasite are currently waiting to be tested. A lot more research needs to carried out if we are to come to any estimation of likelihood about whether this parasite has a played a role in our recent,  wild population observations.

Another theory… 

A few days before Indah’s baby was seen to be missing there was a very large storm in Sabangau. This kind of storm only occurs once every year or so – our researchers were instantly called out of the forest to the safety of camp. Many trees – of all sizes – fell in the strength of the storm. Any bad result of this storm could have easily caused this very young orangutan infant to consequently die.

This would mean any sickness may be only within the two adult gibbons, which may or may not be related to the cause of the baby gibbon’s death. There are obviously many reasons why gibbons might vomit, including due to anything ingested in their diet.

Research continues…
We intend to continue to research the probability of the parasite having infected any individuals we follow. Hopefully some of the poo samples we have collected may help us understand more about the parasitology within Sabanagu. The health of wild populations of any species will affect conservation methods and priorities for that species prolonged survival. It is incredibly interesting to learn about the natural health of wild primate populations, especially of these endangered species.

©Thea Powell

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