It’s a frigid, early-winter night, and across the forests and farmlands of Northland, people are crouching in the dark. They’ve timed this night for the waning moon, so moonlight doesn’t disturb any visitors. Scattered through the night, they sit, silently, and listen.
The sound they’re all hoping for is a high-pitched, piercing cry, or guttural croak – a sign that Aotearoa’s threatened, iconic kiwi has returned to patches of forests that had fallen silent.
The kiwi call count is an annual, nocturnal event that uses relatively analogue technology – human ears – to track how kiwi populations are doing across the region. The data they gather is combined with the “kiwi listening blitz,” a higher tech version, where recording devices are planted and analysed for calls every five years.
This year brought good news: 50% of sites that were silent in 2016 had kiwi calling in 2021. “It’s amazing,” says Ngaire Sullivan, a coordinator at Kiwi Coast, an umbrella organisation that supports more than 180 iwi (tribal) and community groups in Northland working to protect kiwi. “We’re so thrilled with it.” As well as kiwi populating new areas, their calls were still being heard in all of the sites recorded in 2016.
New Zealand has no native land-borne mammals, so many of its native birds are acutely vulnerable to introduced pests. Rats, stoats and dogs have been devastating to the kiwi: only 10% of chicks survive to six months, with more than half killed by stoats.
Northland is one of a few remaining regions where large populations of wild kiwi roam without the protection of fenced off, predator-free sanctuaries. But protecting them requires constant effort by dozens of community groups that trap and kill predators, and ensure dogs are kept under control.
“To sit out there and hear how many kiwi there are and how close they are – it makes the effort put into trapping worthwhile,” says Ayla Wiles, a biodiversity ranger for the Department of Conservation. She says about 150 people crewed listening sites across Northland, and their data goes back 20 years. In some places, kiwi have increased dramatically – at Whangerei Heads, they’ve gone from just 80 kiwi left to over 1,000. “That’s down to the trapping and animal control,” she says. “It’s a community effort”.
The calls of kiwi are particularly distinctive, making them ideal for these listening windows. Males have a high, piercing cry, and females are much lower and more rasping – somewhere between an almighty quack and growl. “If you sit at a site, year after year, you start to recognise certain kiwi that have almost an individual call – think, ‘oh yep, there’s that guy from last year’,” says Sullivan.
She says people are often surprised when they first hear them: “a male has quite a plaintive shriek, a shrill call, and he’ll call maybe five, 10, 15 times – just a beautiful call that pierces the night,” she says. “The female kiwi, however, some people might confuse with one of the possum noises – she’s got quite a guttural call, sounds like she’s been smoking too much.”
As well as gathering vital data, the listening windows also give people precious encounters with the timid, nocturnal bird they’re working hard to save. “It’s such a powerful monitoring tool, because these are nocturnal birds that you don’t generally come across,” she says. “You can be trapping, you know, week after week after week, in the hope that your kiwi are doing well. And then for four nights a year, for just those eight hours … You sit there and get to hear your outcome.”
This article by Tess McClure was first published by The GUardian on 12 August 2021. Lead Image: Kiwi watchers capture bird song in previously silent sites.
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