Largest-ever scientific sound recorder survey undertaken: monitoring the last of the Manumea

The use of automatic sound recorders has revolutionised wildlife ecology and conservation research. This technology will reveal critical new information on the critically endangered Manumea.

In Samoa, the team working on the critically endangered Manumea, or tooth-billed pigeon, turned to a relatively new technology to undertake a groundbreaking survey across the country. Remote automatic sound recorders were placed in the forests and set to turn on and record during key periods of the day.

‘This was the largest sound recorder survey conducted in science to date,’ says Dr Rebecca Stirnemann, a postdoctoral fellow at Australian National University.

While most previous studies typically use 5 to 20 recorders, the team set 72 recorders across 2842 square kilometres in Samoa, a tropical island nation in the South Pacific. ‘We wanted to study where this rare and the very elusive bird is found and what landscape features they need so conservation action can be targeted,’ Stirnemann says. “Because the species is rarer than a tiger and covers a large area, we needed a large spatial coverage.’

With only 200 Manumea birds estimated to remain in the wild, the results from this study are indeed critical for conservation. However, the results are not only relevant for the Manumea. Buried in the thousands of hours of sound recordings are crucial data on other endangered species, such as the Mao and the friendly ground dove species also only found in Samoa. “We now have the enormous task of sorting through the data,” says Samoa Conservation Society Officer Christine Tuioti, who has just completed the task of downloading the information.

Categorizing and analysing thousands of hours of sound files is not easy, but the “soundscape” of today’s Samoa has great value.

“This dataset will also form an important baseline to monitor forests as they change.” says Moeumu Uili, a principal officer of Forestry for Samoa, “For instance, it can be used to show success as restoration projects are implemented or to monitor climate change”.

On the steep slopes of Samoa’s islands, travelling to field sites to deploy the recorders was no small task. Teams spent weeks hiking and working with local communities to honour local customs and involve as many as possible in environmental conservation.

This project was a partnership across the Pacific with the sound recorders lent from across both New Zealand and Australia. “It was only by working together that we could make this happen,” says Dr Stirnemann. The recorders were placed across the country with the help of many volunteers and in collaboration with the Ministry of Natural Resources and Environment, Samoa.

“This project was only possible because the Department of Conservation, New Zealand and a number of private scientists and consultants across Australia and New Zealand lent us the recorders” says Dr Rebecca Stirnemann. The team is also grateful for funding from the Darwin Initiative, the Rufford Conservation Fund and Auckland Zoo that allowed this project to occur.