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Photo: Amelia Geary / Design: Archi Banal
Photo: Amelia Geary / Design: Archi Banal

ScienceMarch 23, 2023

How to boost your backyard biodiversity

Photo: Amelia Geary / Design: Archi Banal
Photo: Amelia Geary / Design: Archi Banal

You don’t need to go to wildlife sanctuaries to see native birds, bugs and reptiles.

This is an excerpt from our weekly environmental newsletter Future Proof brought to you by Electric Kiwi – sign up here.

Recently I wrote a feature for New Zealand Geographic on weeds – it turns out, a lot of our pest plants started out as garden favourites before jumping the fence to wreak havoc on native ecosystems. So this week I wanted to flip the bad backyards narrative, and see how our gardens can instead be havens for native biodiversity.

Make layers

Margaret Stanley, an ecologist at the University of Auckland, says it’s all about the layers: shrubbier plants, grasses and herbs underneath a canopy provide homes for insects, which in turn provide much needed protein for birds. “The more you have different layers, the more you get those different birds, like pīwakawaka and riroriro,” Stanley says. “Plants like cabbage trees are underappreciated because they’re very narrow and they don’t take up much space in the garden, but they actually provide heaps of habitat for invertebrates, as well as nectar and fruit for birds,” she says.

Good lizard habitat (Photo: Amelia Geary)

‘Plant the tree you want to see in 20 years’

Amelia Geary, who lives in Paekākāriki on a quarter-acre block, was inspired to revamp her backyard after hearing lizards rustling in a flax bush, and mowing her lawn for the first time. “It took me three hours and I was like, no. This has to end,” she says. In the areas closest to the beach, Geary chose to replace grass with hardy plants that could survive in sandy soil and the harsh coastal environment – species like spinifex, pīngao, and dune coprosmas. Shrubs and more woody vegetation dominate the opposite end of the garden. She was careful to plant both male and female coprosmas, so they’d fruit, providing kai for the lizards and birds. She even established native mistletoe – a group of plants which have declined considerably since the early 1900s.

Native mistletoe (Photo: Amelia Geary)

Know what you want to protect

The planting – of more than 100 different native species – was just the first step. “I take pest control very seriously. I have about 30 traps, and three cameras for surveillance,” Geary says. “I’m trying to protect the lizards in particular, so I’m trapping for mice, hedgedevils [hedgehogs] and rats.” Once dispatched, the pests are buried in the garden. “Never underestimate the value of a corpse. I caught 35 hedgedevils in one year, their nutrients are now powering the biodiversity that would have otherwise been in their bellies.”

There are other little changes you can make to welcome wildlife, such as constructing rock piles for reptiles, or installing bug hotels for wētā – like Holly Neill, whose impressive backyard transformation was profiled by the Predator Free Trust last year. Ultimately, it’ll be the combination of lots of people taking care of their small patch that will boost our wildlife. “If we’ve got all these little patches throughout the city, we can use our backyards to create corridors that allow biodiversity to move through, effectively making bigger habitat,” Stanley says.

A wētā hotel (Photo: Amelia Geary)

Unexpected treasures

The efforts pay off. Geary’s resident northern grass skinks are enjoying their renovated and expanded habitat. But it’s the booming native invertebrate population that has captivated her. “It’s absolutely riddled with tree wētā, stick insects, moths… so many moths! My favourite time is to go out in the evening after dark on a calm still night with my head torch and spy all the fat caterpillars munching around the Muehlenbeckia.” Stanley, too, has been pleasantly surprised by the variety of invertebrates she now sees. “We’re actually getting beetles and moths. Not just flies!”


Keep going!