How vocalisation helped classify the world's most endangered great ape
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Dr Marina Davila Ross investigates communication in primates, from laughter to long-distance calls in the wild. In the latest episode of Life Solved, she explains how her data helped classify a distinct new species of great ape in 2017.
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Similar, but not the same
The Tapanuli Orangutans are the third and most endangered species of orangutan. Living in rugged, mountainous terrain in South Tapanuli, Sumatra, it was long thought that this species was the same as their swamp-dwelling cousins found in other areas of Sumatra. But the colony Marina has been studying looked different, and they sounded different too!
They have fuzzier hair and moustaches, and the females are very beardy, more beardy than the females from other areas of Sumatra.
Long-calls and behavioural analysis
Behavioural analysis is an important part of understanding different species of animals. Even if they looked similar to the Bornean and Sumatran varieties of orangutan, the Tapanulis had a distinctive long-distance call that gave the game away. Twenty years ago, Marina was recording and analysing audio from primates, which help her and colleagues to eventually spot the difference.
Orangutans need to be able to identify their species through these calls. The results showed that these vocalisations are genetically grounded, and the populations also showed a pattern that matched what we knew about migration.
Marina had walked and camped in forests at night to gather a range of primate calls on a high-quality Sony Walkman. This audio was later analysed as sonograms which denoted unique pitches and frequencies.
Years later, researchers used a mix of analytical techniques from different disciplines to study the Tapanulis and thanks to Marina’s acoustic data, in 2017, they were declared a distinct species. This was just in time to rescue it from potential extinction.
Protecting an endangered species
Plans had been underway to construct a hydroelectric power plant on the site the 800-strong Tapauli population called home. Once recognised as a highly endangered species, conservation took the front seat. Over a million people signed a petition of objection and authorities moved to protect the Tapanuli environment.
We have to protect these orang-utans. Without protection, it has been calculated that within seventy-five years, there will be a decline of over 80%. So it's really important to me to monitor them daily to identify forest areas that are necessary to build forest corridors and to protect more of their habitat.
It’s remarkable to think how close this species came to being wiped out, but thanks to international, cross-disciplinary research between organisations like the ´óÏó´«Ã½ and its partners, this precious population can live on.
You can listen to Life Solved on all major podcast players, whether via Apple, Spotify, Google Podcasts or other apps. Just search for 'Life Solved' and press the subscribe button.
Episode transcript:
Anna Rose: You're listening to Life Solved from the ´óÏó´«Ã½. This is the series where we look at how research is having an impact on our lives in real time and changing our world. In this episode, we'll learn how the sounds or vocalisations a group of animals makes can provide vital data in understanding and identifying different species. What's more, we'll hear how one researchers 20 year old Sony Walkman recordings helped in the identification of a whole new species of great ape. John Worsey interviewed Dr Marina Davila-Ross. Have you ever heard of Pongo Tapanuliensis? It's otherwise known as the Tapanuli Orangutan. It's the third of three species of orangutan and there are only about 800 in the world.
Marina Davila-Ross: So Tapanuli orangutans live in Sumatra and also in Sumatra outside of that specific area, there are other orangutans, Sumatran orangutans and then there are orangutans from Borneo. So just in these two islands, Sumatra and Borneo, orangutans exist. Until the study from2017, there has been this general idea that they are only two orangutans existing in these two different islands respectively. That absolute isolation that occurred through the volcanic eruption, but also earlier than that, about 3.5 Million years ago, there was some separation from the tapanuli and other orangutans in Sumatra.
Anna Rose: Marinas from the Department of Comparative and Evolutionary Psychology here at the ´óÏó´«Ã½ and says the tapanuli orangutan is critically endangered, but we nearly didn't know this at all.
Marina Davila-Ross: The study started actually 20 years ago when Eric Maynard from the Australian National University conducted a survey in South Tapanuli near Lake Toba in Sumatra and found that these orangutans living there are isolated apart from other orangutans in Sumatra, probably as a result of a volcanic eruption that happened about seventy five thousand years ago. And they also look quite different. They had fuzzier ha
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