Band of Brothers

Borneo's endemic Colobines

Borneo's endemic Colobines

There are five doctors in the house. All of them are gynaecologists. There are five lawyers in town, all of them only do divorce cases. Not very useful situations, wouldn’t you say? In fact, society would have a serious problem if every contractor built bridges, and couldn’t build roads or buildings. On the other side, the problem would be even worse, with every doctor, lawyer or contractor having to compete with the other for clients. A better situation is for each doctor to specialise in a different area, thereby serving much more people, and not having to compete with each other. Makes perfect sense one would say.

Well, this is exactly the same situation in nature. The forest needs every type of animal to do something different, like eat a different fruit. The forest could not function if all the animals ate only one type of fruit, from one type of tree. How would the other trees then reproduce? And how would animals and birds survive if they depended on only one type of tree?

When we understand how this works, we can begin to appreciate how incredibly complex our Bornean rainforest is. Scientists have been studying this tree, that fish, the other bird and several monkeys for years and years, and still they keep finding out new things. Little things, but so important things that make nature work. Here’s a story of five monkeys on Borneo, like the five doctors.

These five monkeys are all similar. They all belong to the same family, and are called colobines. They have very long tails and big bellies. They eat only leaves and seeds. No meat. They have two stomachs, like cows. One for breaking down the cells of leaves, and the other to digest and absorb the nutrients they need for energy. They all live on Borneo, and nowhere else in the world.

The Proboscis monkey is the most famous of the five brothers. He is the biggest, has this enormous nose, and lives near water. He has slightly webbed feet, allowing him to swim and therefore live in the vast swamps and mangroves of Borneo. Being the biggest, he needs the most food, and therefore lives where the soils are richest. Trees that grow on nutrient-rich soils have leaves full of proteins. Borneo’s soils are notoriously poor in nutrients, and this is why the Proboscis monkey is not found in the interior of Borneo. This brother can have large families of 8 to 15 individuals.

The Red Leaf monkey is the next brother, completely maroon red in colour, with a black face. This brother divides its diet evenly between leaves, seeds and non-sweet fruits. He uses a huge number of trees for food. His strategy is not to restrict himself to the richest protein sources, but to eat as many of the lower quality foods as possible. His families are smaller, 5-8 individuals.

The Grey Leaf Monkey is found only in the north and east of Borneo. He is all grey with black markings on his face, like war-paint. This brother lives on leaves and seeds as well, but is found deep in the forests, usually away from the coast. His families are medium-sized, about 9 members, and he travels up into the high mountains. He compensates his poor diet by coming down to the ground to get his vitamin supplements from salts in the soils.

The White-fronted Leaf Monkey travels the least, mainly across central Borneo. He has never been to Brunei or Sabah. This brother stays away from the swamps, preferring the hill forests. He has a distinctive crest on the top of his head which points forward, and gets his name from a white spot on his forehead. Because he travels less, he can have larger families, up to 10-15 members. He eats almost entirely leaves, but loves flowers too.

The Bornean Banded Leaf Monkey is the dying brother. He always lived only in a small area, but today he has just one small patch left, between two rivers. He is the most beautiful of the brothers, with red, yellow and black markings. His families are very small, 5-7 members, and he eats leaves and some bitter fruits. He is one of the most critically endangered animals on the planet because his tiny home has been almost completely wiped out.

Our fascinating five brothers have successfully lived together in one town because they each became a little different. They changed their body sizes so that they could do different things, and go different places. They changed what they ate, so each of them always had food. They changed how they lived and how far they travelled, so that they could reach more sources of food. They changed their family sizes to allow them to feed their families in areas where food was poor. And they did this all in one place, their home called Borneo.

Living together is a strategy found everywhere in nature. Humans too need to live together, smartly. We urgently need to learn strategies that do not require any other living thing to give way so that we can continue living.