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Call of the Orangutan: How to Follow an Orangutan

The views expressed are those of the author and are not necessarily those of Scientific American.


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In my previous post, I wrote about the first task in studying orangutan behavior: finding the animals. In this one I’ll explain the second major task: following them.

First things first, not to spoil anyone’s ideas about the glamor of being an orangutan researcher, but in my honest opinion the majority of “follows” are awful! The day starts with waking up between 4 a.m. and 5 a.m. Researchers and field assistants will grab a vital coffee and then stumble around camp with their head torches, blinding anyone that wanted a lie-in as they look for their packed lunches, water bottles and equipment.

The author catches a few winks. The extremely early morning starts and late finishes take their toll on both researchers and field assistants alike. (Credit: Twentino Losa)

Eventually, once everyone (typically one researcher and one field assistant) is ready, you’ll trek out into the jungle in absolute silence (who wants to talk at 4 a.m.?) at a snail’s pace. The aim is to make it to the orangutan nest by 5:45 a.m. before it has woken up. However, especially when following lazy flanged males, this often means we’ll have to wait for as much as an hour in the predawn gloom (which some people might see as a good opportunity to take a nap) before there’s any action.

Occasionally, no matter how early you arrive the orangutan is already awake, and off munching somewhere, creating a confusing situation in which no one quite knows how to find the orangutan in the darkness—but thanks to the noise we know for sure that they’re present!

As I mentioned previously, as a researcher your job is to collect behavioral data from your focal individual. This means that every two minutes you note down a dizzying amount of information:

  • The actual behavior in shorthand code covering virtually every possible variant
  • Its height in the canopy
  • Any item being manipulated or eaten
  • Mother-infant contact
  • Party size and distance (a group is “a party” if they’re less than 50 meter apart, and below this sub-intervals are used: 2 to 10 meters means “social” and 0 to 2 meters means “contact”)
  • Who’s leading travel
  • And feeding tolerance between individuals

On an ad hoc basis we also record all social activities, sexual activities, fighting, playing and vocalizations, and we fill out a detailed checklist about nest making. Every 15 minutes we also take GPS points for ranging, along with producing hand drawn maps.

This probably sounds like a lot of data to collect (a single observation usually fills around six pages on a clipboard) and it definitely takes some practice, but eventually you can glance up at the tree and figure out quickly what’s going on and what you’re supposed to write!

Camp manager Suprayudi notes down the extensive data required from an orangutan ethogram during a follow. (Credit: James Askew)

Of huge benefit to all orangutan researchers is the fact that all of these methods are standardized across all field sites, meaning researchers can share data and easily make comparisons across populations. The benefits of this standardization are showcased in the excellent book, Orangutans: Geographic Variation in Behavioral Ecology and Conservation, a synthesis of orangutan biology that compared data from every site, collected and analyzed by all of the field’s top names in order to develop a theoretical framework explaining the morphological, life history and behavioral variation between the different populations. For me it’s absolutely invaluable and the go-to book for any work that I’m doing!

Back in the field, once we have our orangutan and know how to collect the data, all that is left to do is to follow the orange beastie! This can of course be problematic; some animals do not like being followed, especially if they’re not yet habituated (i.e., used to researchers). These individuals will kiss-squeak endlessly, throw branches, try to urinate on you and, in the case of flanged males, occasionally even charge, though this isn’t actually dangerous.

Fairly quickly, however, animals will usually become less stressed and we’ll normally give them a bit of space if things seem a bit too hectic. Still we’re obligated to follow them wherever they go, which can lead to being dragged up and down hills, through rivers and into patches of the spikiest plants imaginable! Actually, this aspect is pretty fun, as I get to see a lot of the research site I wouldn’t otherwise encounter and it’s a very good workout!

Certainly, following an individual who’s flying around the site is much better than following an individual who just wants to sleep, such as a pregnant female. And I’m sure all orangutan researchers have a (least) favorite story of an individual who woke up, moved 6 meters to a fig tree and proceeded to eat at an invisible height for 14 long and boring hours.

A major difficulty during follows is physically seeing animals that are often 20 meters above observers in the canopy. (Credit: James Askew)

In fact, boredom is probably the major issue with the majority of orangutan follows. A decent amount of the time the animal is out of sight (though, of course, we do try and position ourselves in order to avoid this) or resting or asleep. Along with the focus required to keep taking data every two minutes, once a follow hits around 10 hours, everyone is mentally shot-to-pieces, sullenly sitting around and vocally cajoling the orangutan to make the night nest that put the follow to an end and send us back to camp. Usually the orangutan will oblige between 5 and 6 p.m., although sometimes it’s later, which can prove difficult due to darkness.

Orangutans are unique amongst the great apes in that they build new nests almost every night, and often build them in the daytime too. These nests are flat platforms built by folding large branches together to produce a wide base of branch endings in a butterfly pattern. Next, the orangutan will build a mattress by bending smaller, leafier branches into the mix before finally locking the whole structure together by braiding branches into this mattress to form a strong structure folded into the center.

Interestingly, orangutans at different sites will make special additions to the nest, perhaps indicating a cultural component to this nest building process. These special features seem to be for comfort and include pillows (small twigs, bitten and placed at one end of the nest), roofs (a loose cover of braided branches), blankets (leafy branches laid on top of the body) and even bunk beds (a separate platform above the nest)!

Orangutans make a new nest virtually every night and often during the day, though they will sometimes use old ones if they're still in good condition. (Credit: James Askew)

Once the nest is done, we zoom back to camp at a fierce pace (which makes me realize quite how much slower I am than my Indonesian colleagues), ready to grab a delicious dinner and get everything ready for the next day’s follow. Typically, we’ll repeat this process with each orangutan for a minimum of five days and maximum of 10 days within a given month. However, if the animal leaves the study area or there isn’t enough staff to follow, we might have to abandon the effort sooner.

I do hope I’ve given the impression that follows are often difficult, long and boring grinds, which make me wonder on a daily basis whether I should have studied a more social species! I definitely stand by all that, but the honest truth is: the good days—when the orangutans are being social or behaving in the most astoundingly intelligent way, making us gasp and laugh as we follow them, getting to know the intricacies of their social relationships and their personalities, absolutely—make up for the days of following a lone individual who sleeps for six hours and moves 150 meters.

James Askew About the Author: James Askew is a PhD candidate in Integrative and Evolutionary Biology at the University of Southern California Jane Goodall Research Center. His research is focused on orangutan behavior, specifically the “long call” and its role in social and reproductive relationships. Over the next 18 months he will be running a comparative study of three different populations at sites in Borneo and Sumatra. Follow on Twitter @jinborneo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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