Surveys & Monitoring

This baseline of information allows us to identify population trends and make comparisons between managed and unmanaged populations. It also means any unexpected falls in kiwi numbers can be rapidly identified and action taken, if needed.

Along with kiwi call surveys, metal bands have been put on the legs of some birds. The uniquely numbered metal bands identify individual birds and allow more intensive monitoring of some selected populations.  As many birds as possible are caught wihtin a defined area and radio-tracked for several weeks to plot out their territories and to discover their partners and/or family group members.  After 5-10 years, these banded populations are checked to discover trends in the number of territories, the suvival rate of banded birds and the level of recruitment of new birds into the population.

The challenge for the future is to find ways to survey and monitor kiwi that are not labour intensive, and can therefore be applied to populations spread over larger areas. New techniques being developed include:

• using specially trained kiwi dogs to find birds, allowing the age distribution in a population to be accurately assessed and gives some idea of the status of the population, and whether it has a good percentage of juvenile birds
• learning how to identify individual birds remotely – such as by recognising their specific call, or genetic fingerprinting using feathers or faeces
• developing models that allow the abundance of kiwi to be accurately pinpointed from surveys, such as call counts
• developing tools for remote monitoring and rapid monitoring over very large areas.

Acoustic Recorders

Technology developed in the United States of America (USA) and beig adapted by DOC will enable big improvements in how kiwi calls are monitored.

It has been thought that kiwi do not call during windy or rainy nights, but it may simply be that human ears cannot pick their calls out from the ambient sounds.  As well, human observers can be prone to error, as it is possible to mistake the sounds from possums, morepork and weka for kiwi calls.

 The new acoustic recorders, electronic devices that can record a year’s worth of kiwi calls, will help fill the gaps in information.

The recorders run at pre-set times during the night - through rain, wind and snow.  They will provide a much more accurate record of kiwi numbers than traditional call count methods using the human ear.

Special software turns the recordings into sonagrams (sound pictures) that allow kiwi researchers to quickly scroll through hours of recordings looking for the specific patterns that kiwi calls make.  The sonagrams also identify other animal sounds in the neighbourhood.

As well, the acoustic recorders run over long periods - one has been in place at Okarito for 12 months. That delivers vast amounts of data compared to when people monitor kiwi calls - which is typically limited to just a few nights a year, and are weather dependent.