FRANZ JOSEF, NEW ZEALAND—When I first see the kiwi chick, I briefly wonder if I’m actually looking at a real animal. It’s a grapefruit-sized sphere of fluff with an adorably short version of an adult’s long beak. When it sits still in its dark, red-lit enclosure, it looks indistinguishable from some of the plush toys that fill New Zealand’s gift shops.

Unlike the chicks of most birds, the kiwi’s surprisingly mobile and self-sufficient, even though it hatched just six days ago. It’s too early to tell if it’s male or female, but it already has a name: Kami, after a Maori word that means “force of nature.” And it will soon have company. In the room next door, 22 more kiwi eggs are incubating in an artificial chamber.

I’m in the West Coast Wildlife Center, a stark black-and-lime building in Franz Josef, on the western flank of New Zealand’s South Island. Most of the people in this town have come to trek the glaciers that smear the landscape. But some are here for the kiwis. As part of Operation Nest Egg, a 23-year project to save New Zealand’s most iconic animal, rangers and volunteers capture the eggs of wild kiwis, incubate them in captivity, and rear the chicks till they’re large enough to fend for themselves.

For millions of years, they had little to fend against. The only land mammals in New Zealand were bats, so kiwis evolved to fill the niche that's typically occupied by shrews and hedgehogs, becoming honorary mammals. With their tiny vestigial wings, bristly feathers, and heavy marrow-filled bones, they can’t fly. Then again, they don’t need to. Their attention lies not in the meters above the ground, but in the inches below it, which they explore with long bills that have nostrils at their tip. They use their exceptional sense of smell to probe for worms and insects, and they move with a steady deliberation that belies their bumbling exterior.

Around 70 million kiwis used to trundle through New Zealand’s undergrowth, before humans turned the islands into worlds of fur and teeth. The predators that we introduced—dogs, ferrets, cats, rats, and especially stoats, a larger relative of weasels—slaughtered their way through the kiwi population, reducing it to the measly modern tally of just 68,000 birds.

Most people speak of kiwis as if they are one species, but they are actually five. Kami belongs to the rarest of the quintet—the rowi, which was only recognized as a distinct species in 2003. Today, these particular kiwis are confined to a tiny region called Okarito, nestled among the South Island’s glacial forests. There are only 450 of them left in the wild, and around two-thirds of those were reared by Operation Nest Egg. The West Coast Wildlife Center alone has hatched 232 rowi chicks since it opened seven years ago.

In the wild, half of rowi eggs fail to hatch. Of those that do, around 90 percent lose their lives to the jaws of predators before they reach adulthood. After seeing these depressing statistics in the 1990s, Rogan Colbourne and Hugh Robertson from the Department of Conservation realized that the best way to save the birds was to raise their chicks in sanctuaries, releasing them only when they had outgrown the appetites of stoats, at least. And so, Operation Nest Egg began.

First, rangers find wild rowi and collect their eggs. It’s the males who incubate, and most of them have been fitted with smart transmitters that monitor their movements. If they’re staying still for a long time, chances are they’re sitting on an egg. Then, it’s a matter of reaching into the burrow, which can be anything from a hole in the ground to a rotten log, and pulling the egg out—sometimes from underneath a brooding bird.

Kiwi eggs are huge, and disproportionately so. They can account for up to a quarter of a female’s body weight, and they’re only slightly smaller than the eggs of much larger birds like ostriches, emus, and cassowaries. Kiwis are closely related to these giants, and they all have one thing in common: They can rear up and deliver surprisingly powerful kicks. Kath Morris, who works at the West Coast Wildlife Center, tells me of a friend who was camping in kiwi territory when one of the birds put its foot through his tent. She also shows me a kiwi-inflicted scar across her wrist. “You don’t notice you’re bleeding until later,” she says.

After the volunteers avoid lashing feet and successfully secure an egg, they place it in a cool box and send it to a captive rearing facility. There, volunteers “candle” the eggs—shining a light on it to check for cracks and to inspect the embryo within. Once the egg is inspected, cleaned, and weighed, it is placed in an incubator that slowly turns it, mimicking the actions of a incubating male. (Colbourne discovered that behavior by using sensor-studded dummy eggs to work out how wild kiwi actually incubate their eggs.)

After 90 days or so, it’s time for the egg to hatch. The kiwi chick sticks its bill into an air sac at the top of the egg, and starts to squeak. It then punctures a small hole in its shell, and uses its already strong feet to push its head out. In one case, a chick got stuck because it accidentally kicked the bottom out of its shell. Fortunately, quick-thinking keepers repaired the damage with tape.

A newly hatched chick, like Kami, doesn’t have to eat. For a week or two, it subsists on the yolk from its egg, which it carries around between its legs. Once the yolk is exhausted, keepers feed the chicks on a mix of fruit, vegetables, beef mince, and ox heart. (Kiwis are born independent, and don’t imprint on their parents—or humans.) The birds are less than a pound at birth, and the goal is to get them closer to three pounds—heavy enough to defend themselves against stoats and thrive in the wild.

Early on in the project, researchers realized that the newly released youngsters would frequently run afoul of adults, who were defending their territories. “They were safe from stoats but they weren’t safe from kiwis,” says Colbourne. “We lost a lot of the young birds.” The problem was that these hand-reared youngsters had never learned kiwi social etiquette, and would inadvertently provoke fights that they were too placid to finish.

To socialize them, the team now transport the chicks to crèche islands—predator-free offshore sites, where a young kiwi can learn how to kiwi. “All the young birds socialize, get into scraps, and learn how to run away,” says Colbourne. “They learn that if they see another kiwi, they shouldn’t run up to it. And if they get chased, they’ll be fit enough to run.” After some time, they’re taken back to Okarito and released.

Without all of this intensive work, only two new rowi would make it to adulthood in a single breeding season. Now, around 50 do so. The population is growing, and the species was recently downlisted from “nationally critical” to merely “nationally vulnerable.”

“We’ll get to the point where we have huge numbers, and it’ll be a matter of where can we put them,” says Colbourne. “It’s almost been too successful.”