Kiwi Listening 2024

Volunteers across New Zealand are once again lending their ears to the Annual Kiwi Call Count, a citizen science project that provides essential data on local kiwi populations. From 27 May – 14 June and 24 June – 25 July, dedicated individuals brave the chilly nights to participate in this unique conservation effort. Armed with patience and warm coats, volunteers listen intently to the distinctive calls of kiwi at designated ‘listening stations’ throughout the country.

North Island Brown Kiwi - Hauturu July 2019

When kiwi calls are monitored consistently in the same locations over several years, it provides valuable insights into the trends in kiwi numbers and distribution. Are volunteers hearing more, fewer, or the same number of birds compared to previous years? Are kiwi still in the same locations, or has their habitat range shrunk or expanded? Monitoring over time helps us understand how the kiwi population is faring and how their habitat may be changing.

The Forest Bridge Trust’s ecologist, Dr Virginia Moreno, has organised the kiwi listening schedule across our area, and the Community Liaison team is organising kiwi listening events to engage the community.

As well as mobilising our team of dedicated listeners we’re also deploying automatic recorders to help us monitor kiwi trends and expansion in the Tawharanui and Mataia buffer zones. “We plan to continue this program this year. With the recent translocation of kiwi to Tamahunga, we now have a new population in our area, ” explains Virginia, and there is great interest in understanding their progress and movements”. The Tamahunga Trappers have been monitoring the released kiwi using radio tracking which provides valuable data on the newly established population. However, that method can only be used for a limited time post-release, after which the transmitters are removed and the primary tool for assessing population success becomes call count monitoring.

“Since we know the exact number of kiwi in the Tamahunga population, initiating call count monitoring now allows us to establish a baseline dataset calibrated against a known bird count,” says Virginia. “It’s important to note that chicks born last year are not radio-tracked, so their dispersal (typically averaging 6 km) is unpredictable. Therefore, having monitoring posts beyond the release site is essential. These juveniles will start calling when they reach maturity at around 2-3 years old.”

The Forest Bridge Trust is supporting the Tamahunga Trappers in establishing long-term monitoring, with a few of our team members volunteering to listen in the evenings.

“It can be discouraging in the beginning, some stations do not pick up calls in the first few years, but we are confident that we will reach a point where all stations detect kiwi calls, and there will be a need to expand even further,” reports Virginia.

So what is an ideal outcome?

A ‘high density’ kiwi population typically registers around 5 calls per hour on average. Last year, Tawharanui recorded an impressive average of approximately 11 calls per hour, indicating a densely populated area. This is why Tawharanui is now being used as a source for translocations and reintroductions, such as at Tamahunga.

In contrast, Mataia began with a modest 1 call per hour in 2014, but recent years have seen this rate exceed 5 calls per hour. The goal across these sites is to reach and sustain the 5 calls per hour threshold, signifying a healthy and thriving kiwi population. However, achieving this target can be a gradual process, often taking several years of concerted conservation efforts.

We look forwards to reporting the results of the kiwi call count in the Spring.

Click to hear the calls of the male and female Northern Brown Kiwi.

  • The call of the male kiwi is a repetitive (8-25 notes) high-pitched whistle.
  • The call of the female kiwi is a repetitive (10-20 notes) coarse rasping note.
  • Ruru (morepork) and possums are often confused with kiwi calls.

Learn more about completing a kiwi listening survey. Kiwi-Call-Count-Survey_Instructions-for-Listeners_Revised-May-2020.pdf (kiwicoast.org.nz)