Our Changing World: Recruiting the birds to bring back the bush

Follow Our Changing World on Apple, Spotify, iHeartRadio or wherever you listen to your podcasts

Standing at the edge of a flat grassy meadow, the hills of Waikereru ecosanctuary fill the horizon. One hundred hectares of steep-sided land that was once pasture is now slowly returning to native bush.

But could the local manu be intentionally recruited to speed this process up?

Free feathered labour

The ecosanctuary, just a few kilometres outside Gisborne, was established by Professor Dame Anne Salmond and her late husband Jeremy in 1999.

It encompasses Longbush Reserve - a patch of forest open to the public where Anne and her siblings used to come to swim on hot summer days. There's also the 1769 Seed Archive garden - which contains several rare and endangered local plants - and a harakeke flax library with different varieties valued for their weaving properties. The Welcome Shelter, an outdoor educational space, caters to about 1,000 schoolchildren each year.

But the hills make up the majority of the area.

They were grazed for some time after Anne and Jeremy bought the land, but now the kānuka shrubs that pop up as the opening salvo of regeneration are flourishing.

However, to get to a mature, species-rich native forest through natural succession takes time, and for Anne, these steep-sided hills must get there as quickly as possible.

"To hold this landscape together because it's so erodible... you really need a very biodiverse natural forest with a whole complex underground architecture of roots," she says.

Hence why Waikereru are collaborating with Tāne's Tree Trust to trial 'seed islands' - groups of native trees known to provide fruit for the birds. The idea is that after a few short years, these fruit feasts will recruit free feathered labour to disperse the seeds nearby.

Waikereru got its name for a reason, says Anne, and these renowned berry-gobblers are crucial in the trial. "The kererū don't charge us anything. They just go up there, we feed them, then they go up there and gloriously poop all over the place."

Following a geological and botanical survey, the team have set up an experiment with different trees planted in different parts of the hills and will monitor them in the years to come to see what works best.

A mosaic vision for Tai Rāwhiti

Located near the Waimatā river, this area, like so many others, was badly affected by Cyclone Gabrielle in 2023. The river was jammed upstream by forestry slash and logs, eventually bursting and scouring out its banks, taking out parts of the road, as well as fences and plants.

"But that was nothing compared to what happened to many people upriver," says Anne.

Working with others in the region and with the green-growth-focused charity Pure Advantage, she is advocating for a 'mosaic' approach to land use in Tai Rāwhiti.

In this vision, steep-sided hills, highly erodible land and strips alongside waterways would be returned to native forest, with the money to support this regeneration coming from a 'gold standard' carbon credit. Anne says this carbon credit would be based on indigenous forest, monitored using satellites. The forest would not be intended for short-term harvest, but instead aimed at giving landowners a steady income out to 2050, the second Paris agreement goal.

This idea has been laid out in a proposal and business case put together by Pure Advantage and Tāne's Tree Trust called Recloaking Papatūānuku.

Despite the local, national and global challenges, Anne remains positive about our ability to change course.

"It's possible to make a real difference quite quickly. But for that to happen, people have to believe you can do it. And they need to understand that it's not that hard, and it's not that expensive, and that it's a joy."

Sign up to the Our Changing World monthly newsletter for episode backstories, science analysis and more.