Fiordland Kiwi Diaries: How to count kiwi

By Jamie McAulay, Senior Ranger – Biodiversity

Our kiwi monitoring at Shy Lake continues, but we still don’t know much about the kiwi in a lot of other areas.  Senior Ranger Jamie McAulay recently led a trip into the heart of Fiordland to check out the kiwi population at a new site. Read on for his guide to counting these elusive birds.

How to count kiwi – an instructional guide.

So, you want to count some kiwi?

You want to see if all your hard yakka removing invasive predators is working, and the population is starting to rise once again? Well friend, this is the guide for you. Read on for a step-by-step guide to counting kiwi in the night.

Step one – hard yakka.

Step one involves climbing lots of hills. The first step is understanding why kiwi are declining in the first place. This is the most labour-intensive step – it involves catching kiwi, attaching radio transmitters, tracking them through the bush, placing cameras on their nests, and following their babies to see who survives.

It tells us a lot; it tells us exactly how many kiwi are in an area, how many survive, how many make chicks and how long they live for. The Fiordland Kiwi Diaries blog tells the tales of this effort – our study of Fiordland Tokoeka chicks at Shy Lake.

Tim’s updates make it clear – it’s hard yakka. Long nights working in the wet bush till the wee hours, catching kiwi, attaching transmitters, multiple return visits to nests, climbing hills, traipsing through wet Fiordland bush, climbing some more hills, and camping out in a small monitoring hut in the hills.

This step is crucial; understanding the problem and how to fix it. But you don’t really want to go through all that every time you do some predator control…

Step two – a kiwi map

So, by now you’re sick of climbing hills, right? Now you’ve figured out what’s attacking your kiwi and you’d rather spend your funds on actually protecting them? You set to work running predator control programmes like community trapping or the hugely successful Tiakina Nga Manu aerial 1080 work. You know from the above study what’s harming the kiwi, and you know you’re controlling predators and should see a good result (legend!).

But you’d still like to check in every few years, right? Just to make sure that the good results you saw above are still happening. You need a kiwi map.

Get yourself some specially trained kiwi tracking dogs, assemble a team of crack kiwi handlers, and go out all night and catch kiwi. Attach radio transmitters so you can locate and visit kiwi daily and get an idea of who is living where. Kiwi are a territorial bunch, strictly defending their patch of Fiordland forest. Following them lets you build a map of who’s living where – you can then count the territories and how many kiwi are living in any one area.

Doing a ‘check in’ count every five or so years will give you an actual count of the population in a small sample (e.g. – one valley) and a look at how the numbers change over time. Attaching lightweight metal bands to the bird’s legs (with a unique number on them), you can see who’s still around in 5, 10 or 15 years’ time. Turnover in the population tells you about old birds dying or new chicks coming into the breeding population.

Step three – bush microphones.

Pictured is an ‘acoustic recorder’, AKA bush microphone. For the next step in counting your kiwi, you will chuck a network of these microphones out all across the wilds. You’ll set them to record for several hours every night, for weeks at a time. This is the equivalent of thousands of hours of human effort listening for kiwi and counting calls (a classic kiwi counting technique). DOC are working with the technology sector to develop AI algorithms that automatically recognise those iconic kiwi calls from these microphones.

That will mean you, keen kiwi saviour, can deploy these microphones all over the place once a year as a cheaper, easier way to measure the long-term change in the population – and over the coming decades watch the number of calls of tokoeka slowly increase across your patch.  How good is that?!

Lucky for you, we are also busy calibrating the number of kiwi recorded on the microphones, against the real numbers in step two above!

Step four – and now you wait. 

Step four is part patience, part waiting, and then some more patience.  

Two kiwi make one egg, which doesn’t always hatch even in the best of conditions. Even with fantastic predator control in place, some of your cuddly little kiwi chicks will die from disease or ‘misadventure’. Of the ones that do survive, it will be another 3 to 5 years before they even reach maturity and start to hold a territory or call for a mate and start adding little kiwi chicks of their own. Then another 3 to 5 years before their chicks start adding to the population. Any change in population is likely to be slow (but totally worth it!); patience is key.  The good news is that kiwi can live for 40 years or more and will be cranking out chicks to grow your population of taonga for many years to come.

Congratulations! You now have a robust monitoring design in place!

This is what scientists call a ‘hierarchical monitoring design’ – with multiple levels of monitoring intensity to inform different information needs about the population over time!

For the Save Our Iconic Kiwi Operation, the hope is once that once we have monitored a bunch of kiwi chicks through a 1080 operation and can see a real benefit in terms of kiwi chicks surviving (we’ll keep  you updated through this blog), we can roll out predator control to a far wider area. We’ll have 5 yearly check-ins at key sites to ensure we’re getting the results we’re counting on, and a network of bush microphones to see the change over a wider area of Fiordland over the next 30 years.

Wish us luck!