Kiwi | San Diego Zoo Animals & Plants

The kiwi existed for millions of years with only one natural predator—the now-extinct laughing owl—and no threats of any kind. When the Maori people established themselves in New Zealand in the 1300s, they used kiwi feathers to adorn cloaks worn by their chiefs and used the birds as food, hunting them at night by imitating kiwi calls. But in the late 1800s, settlers moved into kiwi territory, bringing dogs, cats, ferrets, stoats, and rats that ate kiwi eggs or the birds themselves. The settlers prized kiwi feathers, too—for trout flies! Kiwi leg bones were popular as well for making pipe stems.

New Zealand passed a law in 1908 prohibiting the hunting, capture, or killing of kiwis, but the $100 penalty did little to control the situation, and in 1921 the kiwi was declared an “absolutely protected bird.” Its popularity grew, and the kiwi was adopted as New Zealand’s national emblem. Coins, postage stamps, fighting troops, and shoe polish all carry the name or image of the unique bird. New Zealanders even accepted the nickname “kiwis” given them by their allies during World War II.

Today, 80 percent of kiwi habitat has been destroyed, and the birds continue to fall prey to dogs, weasels, cats, ferrets, pigs, people, cattle guards, cars, swimming pools, and possum traps. Still, the birds are highly adaptive and have been seen in New Zealand cow pastures and plantations. Every year, 95 percent of all kiwi chicks are killed before they reach the age of 6 months, and every 2 years the kiwi population decreases by about 10 percent.

A few years ago, New Zealand began a kiwi recovery program. People living near kiwi areas have learned to keep their dogs leashed and to slow their cars when they see a kiwi caution sign by the road. Operation Nest Egg collects eggs from the kiwi nests and raises the chicks until they are large enough to defend themselves against predators.

In 2009, San Diego Zoo Wildlife Alliance formed collaborations with local ranchers on a private island off the coast of western New Zealand, Massey University, in-country scientists, and the indigenous Maori people to delve into the ecology of the brown kiwi, which has been in decline for decades. Learning about the reproductive ecology of this bird is the only way to ensure that its populations will survive and thrive. The island is secluded, protected habitat with a high density of kiwis.

Techniques were developed in our labs to identify individual kiwis by their DNA and, and ultrasound procedures were used to monitor growth of ovarian follicles to estimate egg-laying time. This newfound knowledge was then successfully applied to birds on the island. By monitoring egg development, we hope to discover ways to improve fertility and survival of eggs at our facilities.

Important data can also be gleaned from radio-tracking devices on the birds. After months of fieldwork, 47 adult kiwis on the island now have a radio transmitter attached to a leg, and 41 kiwi nests were documented, allowing us to explore the importance of habitat and behavior on the nesting success of this rare and reclusive bird.

The birds are identified with transponder tags, such as those used to microchip domestic pets. The radio transmitters reveal a great deal about where the birds go and how far they travel for food. One area of study is mate choice and how long kiwis stay together. Ongoing conservation work will compare hormone levels and also observe chick dispersal patterns for this long-lived bird. A few fascinating facts have emerged from our efforts so far, such as finding three males incubating a single egg!

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