Sumatran orangutans (Pongo abelii) have been found to plan their travel route ahead of time, and then share it with other apes to let them know

The Sumatran orangutan (Pongo abelii) is one of three species of orangutan, found on the island Sumatra in Indonesia. It is considered to be the most social species of orangutan, and they are considered very intelligent as well. Some time ago, they were shown to be capable of using tools, in which they use specialized sticks to extract insects from logs and other places that they cannot reach without a tool. In this post I want to talk a bit about a completely new paper published out this ape, in which they believe that they are capable of planning their travel route, but to understand how this works we first need to look a bit at the social structure of the Sumatran orangutan.

A baby Sumatran orangutan. Image by Michaël CATANZARITI, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

Social behavior of the orangutan

The Sumatran orangutan is primarily eating either fruit or insects such as ants and termites, but they are still a social animal that will often eat together with other members of its species. In contrast to many other apes, the groups that eat together and live close to each other is not exclusive, so new members can join while old members can leave as they see fit. Each group is lead by a big, dominant male, and consists of this male plus females of all ages. The non-dominant males prefer to stay alone, and generally don’t have any contact with other males, but mature males are a lot more rare than females, possibly due to having a higher mortality rate.

A close-up photo of a male Sumatran orangutan. Image by Aiwok, posted with the GNU Free Documentation License, Version 1.2.

The male orangutans plan their travel route and share it with the females

It’s time to return to the newly published paper about how the orangutans plan their travel now that we are aware of the social structure of the species. The premise for the paper is that researchers from University of Zurich followed 15 different dominant male Sumatran orangutans for several years to learn about their behavior. When following them, they would learn that these males emit loud yells every few hours to let the females know where they were, so that they could follow. Often these calls were also found to signal a change in the travel plans, such as a change in direction.

The yell is also believed to scare away any other male orangutans in the area, so they won’t end up meeting each other by chance. However, these findings were nothing new, but further strengthened a theory that has been published before.

What they do however found out is that at the end of each days’ traveling, the dominant male would give a very long call that could last as much as 80 seconds. When the females hear this call they go to bed for the evening, and most interestingly learn which direction to travel in the morning! The scientists believe that the females know which direction to travel in the morning without getting a morning yell from the male, and the data collected by the research team back this hypothesis.

Planning for the future is very rare in non-human animals

As you have probably guessed, it’s very rare for animals to show signs of planning for the future, and behavior such as storing food for the winter is considered to be instinct, not a conscious plan. However, some species are believed to be able to plan for the future, and now we probably have to add the Sumatran orangutan to the list of these animals.

Image by Rufus46, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

Thanks for reading

Before I end I want to make sure you guys are away that the Sumatran orangutan is considered to be critically endangered by the IUCN, which means that it has a very high chance of going extinct in the near future. Not only is the jungle it lives in being logged (mostly illegally), but it’s also hunted by some people.

Anyway, thanks for reading! I hope you learned something new, and make sure to leave a comment below if you have anything to share. And if you want a deeper look into the information I wrote about, then make sure to click on those links that are scattered in the text to read the original source material.