Close up of orangutan holding onto a branch. Life Solved logo and episode title on left.

How vocalisation helped classify the world's most endangered great ape

  • 27 July 2021
  • 15 min listen

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.

Dr Marina Davila-Ross, Reader in Comparative Psychology

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.

Dr Marina Davila-Ross, Reader in Comparative Psychology

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.

Dr Marina Davila-Ross, Reader in Comparative Psychology

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 University of Portsmouth 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.

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