Our Changing Word heads to Whangārei to speak to a Northland Regional Council scientist whose been using stormwater drains to estimate the scale of our plastic pollution problem. Plus, just outside Christchurch, one of New Zealand’s biggest lakes is home to the ‘canary in the coalmine’ of wetlands. The secretive and elusive Australasian bittern seems to be in trouble - how can we help?

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Learn more:

• Join Alison Ballance on a kayak across a lake to listen to some booming bittern crooners.
• Listen to the nine to noon interview with John Sumich about the 2025 Matuku muster.
• The research into microplastics was part of the AIM2 project, which was reported on in 2021 as part of the OCW episode ‘Unwelcome visitors’.
• Another source of microplastics is textile waste, but an international project is looking to a future where our clothes are fully biodegradable.

Guests:

• Richard Griffiths, Northland Regional Council
• Peter Langlands, Bittern Conservation – New Zealand
• Harry Caley, Department of Conservation

Go to this episode on rnz.co.nz for more details

In Dunedin the local tree crop association has been looking after a heritage apple orchard, but some mixed up labels meant they weren’t quite sure what varieties they had. A chance encounter at a public open day sets one young researcher on a scientific quest to ID them all. Plus, in a nursery in Rotorua, a propagation scientist is figuring out the best way to grow a native tree from cuttings.

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Take a (very) large egg, some insects (plus specially developed food), and a safe place to put on weight for a while. This is how you grow a kiwi, and improve wild survival rates from 5% to 65%. With over 2,600 hatches across their 30 year history, the National Kiwi Hatchery have a lot of experience under their belt, but there's always more to learn from our iconic national bird. Our Changing World visits the hatchery to learn how they combine conservation and eco-tourism to help grow kiwi numbers.

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Learn more:

• Operation Nest Egg has also been a great success for the rowi kiwi, the only remaining wild population of which lives in Ōkārito on the South Island’s West Coast.
• In July 2025 little spotted kiwi were found on New Zealand’s mainland for the first time in 50 years. Two chicks and eggs were subsequently brought to Willowbank Wildlife Reserve in Christchurch to allow them to get to stoat-proof weight.
• With a lot of help, and stoat trapping, brown kiwi are returning to the wilds of Wellington.
• Candling is also used to track kākāpō embryo development and egg fertility, learn more in episode 12 of the Kākāpō Files II podcast.

Guests:

• Emma Bean, manager of the National Kiwi Hatchery
• Carole Dean, kiwi keeper, National Kiwi Hatchery
• Rebeca Bothamley, tour guide, National Kiwi Hatchery

Go to this episode on rnz.co.nz for more details