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New Zealand’s five kiwi species are all threatened by loss of habitat and by predators such as stoats and rats. They need to be actively monitored to check where birds are, how well they’re surviving, and whether or not they’re successfully raising chicks. Getting this kind of information on kiwi is difficult; they are nocturnal, have large territories, and often live in hard-to-access areas with challenging terrain.

Existing monitoring work such as radio-tracking and periodic capture-recapture surveys using trained dogs to sniff out kiwi in their burrows, can be both invasive (requiring capture and handling of the birds), and labour-intensive. Other survey methods rely on sound; listening for, and counting calls, and/or setting up recorders to do this, can provide a limited amount of information.

laura putting up a recorder for bioacoustic monitoring

What we’re doing

At Atarau Sanctuary, we’re developing a monitoring method that is non-invasive and provides detailed information about roroa populations. We are doing this by combining several relatively new hardware and software tools to individually identify roroa based on their calls. We use cameras and recorders in the wild and in the sanctuary to work out how the birds behave and interact.

Automated recorders, like the AudioMoths we use, are much simpler and cheaper than they used to be, so we can collect lots of raw data. Part of the fun of it is working out how we can make it work, and the technology is getting faster and better all the time.

We have trained the commercial software package Kaleidoscope, from Wildlife Acoustics, to do the initial detection of roroa calls. From there, we have written a process in an open-source program called R, to clip, save, and measure calls found by Kaleidoscope.

We are using this process to determine which combination of measurements does the best job of reliably identifying the individual who made the call. For this analysis we are using a set of the loudest, clearest calls gathered near known nest sites, so we have high confidence in who the callers really are. We are also gathering and measuring as many calls as possible from the wider network of recorders.

Why we are doing it

New Zealand’s five kiwi species are all threatened by loss of habitat and by predators such as stoats and rats. They need to be actively monitored to check where birds are, how well they’re surviving, and whether or not they’re successfully raising chicks. Getting this kind of information on kiwi is difficult; they are nocturnal, have large territories, and often live in hard-to-access areas with challenging terrain.

Existing monitoring work such as radio-tracking and periodic capture-recapture surveys using trained dogs to sniff out kiwi in their burrows, can be both invasive (requiring capture and handling of the birds), and labour-intensive. Other survey methods rely on sound; listening for, and counting calls, and/or setting up recorders to do this, can provide a limited amount of information.

Who we’re working with

When we have young roroa living at Atarau Sanctuary, we run both automated recorders and trail cameras to observe their behaviour and capture any calls they may make.

In the field right now, we are closely collaborating with the Paparoa Wildlife Trust (PWT) to work with roroa they are monitoring with radio-transmitters; this means we do not need to capture, handle, or fit transmitters to roroa to do our work. When the PWT kiwi ranger detects that a monitored pair is nesting, we work with them to place additional recorders near the nests without disturbing the birds.

PWT is rotating a set of automated recorders around different catchments in the Paparoa Range to listen for roroa. We process those recordings for PWT to help them determine where roroa are living.

As well as this, we run recorders with Operation Nest Egg (ONE) chicks and a captive adult roroa. Piki, at Willowbank Wildlife Reserve in Christchurch. The Department of Conservation and the Friends of Flora also share roroa recordings with us, adding a huge number of calls from birds throughout the roroa’s range to our library.

Laura and Beth
8 littlest kiwi

What we’ll do next

Once we know what combination of measurements is best at identifying individuals, we will use measurements from other calls to match up calls with known-ID birds, and will estimate how many other birds are likely to be represented by other calls we’ve captured.

Using recorders to locate individual birds requires more accurate GPS capability and time-synchronisation among recorders than is feasible at the moment. We will set up dense networks of recorders around known birds to have a closer look at their calling behaviour; this will help us understand more about their social interactions and habitat use. We will also use data from recorder networks to determine the best way to deploy recorders in areas with unknown numbers of birds, when the aim is to get a good estimate of how many different individuals live there.

The library of individually-ID’d roroa calls will be used as training data for AI.

It’s important to us to share our results, and consider how to apply them to other species and in other areas.

Read more about what we’re doing on ResearchGate.

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