Have you been outside at night and heard the call of ruru, or maybe it sounds more like morepork to you? Ninox novae-zelandiae, the ruru or morepork, is our only surviving native owl. Scientists are now using its characteristic call to discover more about this iconic species.
The term ‘acoustic’ refers to the study of sound, and monitoring – in conservation settings – is about gathering the data needed to make decisions. People have always used sound to provide information about birds. In Aotearoa, we have been using simple acoustic monitoring, listening and gathering information about birds – where they live and if they are thriving – for hundreds of years. There is a large volume of mātauranga connected to bird calls and the presence of bird species in different areas.
The ruru call people tend to know the most, of course, is the ruru or morepork call, but these birds make quite a few other calls that people are often less familiar with.Neil Fitzgerald, Manaaki Whenua – Landcare Research
Acoustic recording devices
Technological developments have created easily accessible acoustic recording devices. These allow scientists, conservation groups and individuals to gather large volumes of acoustic data. Acoustic recording devices have been used successfully in collecting data on kiwi and bat populations and in marine environments.
There are different types of acoustic recording devices, but most consist of a microphone, power source (such as batteries or solar panels), memory card and the electronics and firmware to make it go. Some people have adapted cell phones to use for this purpose. A waterproof cover is also helpful.
Acoustic monitoring devices are useful because, unlike people, the devices don’t mind if it’s night-time or if the weather is bad. The devices can also gather large amounts of data over long periods of time, making it more likely that different bird calls will be recorded.
Project Ruru – Kei hea te ruru e koukou?
Neil Fitzgerald, ecosystems and conservation researcher at Manaaki Whenua – Landcare Research, is part of a team collecting information about ruru in the Waikato area. The project started by gathering mātauranga around ruru, and it is using science as a tool to help answer questions raised by whānau.
Acoustic recording devices are being placed near marae and are programmed to pick up sounds during certain times of the night. The data, once collected and analysed, should help answer questions about whether the ruru are still living in these areas.
Sorting through the data
Once recordings have been made, scientists use software to help sort through the large amount of data to find specific sounds. These sounds can be visualised using a spectrogram – a graph showing the frequency of sound over time. The amplitude or volume of the sounds is depicted in different colours.
The Project Ruru team plan to go back to the marae and share the information they have learned about which areas detected ruru calls during the recorded timeframes. This information can then help mana whenua make decisions about habitat restoration and conservation.
Read about the ruru and its connections to repo (wetlands):
The Connected article Can you hear that? provides an overview of sound, briefly addressing: characteristics of sound waves, how the human ear works, hearing loss in humans, how animal ears work, echolocation and sonar.
This article provides more in-depth information about ruru and repo: Ruru – he tangi na te ruru – conversations in the night by Rangi Mahuta (Waikato), Cheri van Schravendijk-Goodman (Te Ātihaunui a Papārangi, Ngāti Apa, Ngāti Rangi) and Huriwai Paki (Ngāi Tūhoe).
Discover more about ruru with these websites:
Learn more about using an acoustic recording device with this instruction sheet from the Department of Conservation.
With thanks to Neil Fitzgerald, researcher at Manaaki Whenua – Landcare Research, the Ruru-Kawau Project team, Cheri van Schravendijk-Goodman and Swampfrog Environmental & Tree Consultants.