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Article by Tim Johnston in the NY Times
CHRISTCHURCH, New Zealand —
In the thousand or so years since humans discovered the remote islands that make up New Zealand, three-quarters of the indigenous bird species have been driven to extinction, and until recently, it looked as if the kiwi could follow.
That would be a loss for the environment, but also for national pride; the kiwi, a small flightless bird that nests in burrows, is the national bird and has become something of an improbable national symbol. The country’s dollar is named after it, and New Zealand’s residents are often labeled “kiwis” by outsiders.
Now, environmentalists are becoming more hopeful that a project started in 1994 will pull the beady-eyed bird back from the brink.
Kiwi numbers have declined rapidly over the past century, as populations struggled with the twin threats of shrinking habitat and expanding legions of new predators.
Hugh Robertson, who runs the Kiwi Recovery Program of New Zealand’s Department of Conservation, estimates that there were as many as five million kiwis when European settlers arrived in the 1820s and that the population now stands at 75,000.
“It’s because of people and introduced predators: ferrets, stoats, weasels, dogs, cats,” said Jeremy Maguire, manager of the Willowbank Wildlife Reserve just outside the town of Christchurch. “They are a species in decline, and if it continues at the current rate, they will become extinct.”
There are five species of kiwi, a smaller nocturnal relative of New Zealand’s now-extinct moa, and, more distantly, the emu and the ostrich. All kiwi species are listed on the country’s endangered species list. But two of them, the Rowi and Haast Tokoeka, are down to fewer than 300 birds, earning them a place on New Zealand’s “nationally critical” list, its most extreme category of endangered species.
The near absence of mammals in New Zealand until they arrived with white colonizers meant that many bird species evolved into flightless ground-dwellers, leaving them vulnerable to the incursions of predators.
“In our case, the stage was set for a spectacular tragedy,” said John McLennan, who has studied the kiwi for 20 years.
Mr. McLennan estimates that the kiwi’s numbers are declining 2 percent to 5 percent a year, depending on the species.
“Our flightless birds took an incredible hammering,” said Mr. McLennan, who is a trustee of the nonprofit organization Save the Kiwi.
The birds are insect eaters with an acute sense of smell and, because they are flightless, their feathers resemble hairs more than traditional avian plumage. Their bones are filled with marrow, again more like mammals than birds, which usually have hollow bones.
When humans arrived 1,000 years ago from other South Pacific islands, they used fire to clear the forests, starting an erosion of the kiwi’s habitat that gathered speed over time.
And when the Europeans arrived, they brought other animals, which now pose the greatest threat. Kiwis evolved in a wooded environment where there were few natural predators apart from various eagles.
The adults weigh at least about 2.2 pounds, and can hold their own against many of the smaller predators, but young kiwis have fewer defenses. Surveys suggest that in the wild, only one in 20 kiwi chicks survives its first year.
Mr. McLennan said that the Conservation Department and other groups aiding the kiwi put out traps and poison to control the predators, but that has proved an expensive and far from complete solution.
So New Zealand’s government agencies have partnered with local communities, nonprofit groups like Save the Kiwi and commercial operations like the Willowbank reserve, to tackle the problem by trying to protect the birds until they have a better chance of defending themselves.
The plan, called Operation Nest Egg, is simple in conception but difficult to execute. Eggs are taken from kiwi nests in the wild and incubated in places like Willowbank. The newly hatched chicks are then taken to protected areas, many of them on isolated islands off the coast without predators, for about a year until they are big enough to fend for themselves. Then they are returned to the place their egg was found.
The program began in 1994, but it has taken a while to perfect the process. It is expected to pass something of a milestone early next year when it hatches its 1,000th chick.
Mr. McLennan says each chick that is returned to the wild costs about $2,750, a reflection of the difficulty in getting the eggs.
The remaining kiwis tend to live in remote corners of New Zealand, and each pair of birds — they remain monogamous for life — controls a territory ranging from 12 to 100 acres, making it extremely difficult to find the nests.
The egg collectors travel with a “kiwi caller,” who can imitate the call of a male kiwi, or sometimes a tape recorder. Male kiwis incubate the eggs, an evolutionary necessity because females lay eggs as large as 30 percent of their body weight and need time to recover.
When the males run out to chase off the intruders, the collectors can trace them back to the nest and take the egg to places like Willowbank.
Mr. Maguire, the Willowbank reserve manager, says the chicks seem to suffer few ill effects from not being brought up by their parents and seem to thrive on their return to the wild.
After a slow start, Operation Nest Egg is picking up momentum. Its success rate is rising, and similar programs are starting throughout the country.
Mr. McLennan is cautiously optimistic that Operation Nest Egg will stem the kiwis’ decline.
“Because the rates of decline are relatively low at 2 to 5 percent, you don’t have to add many birds back into the population to make it break even,” he said.
source: NY Times article by Tim Johnston on 12/28/07 www.nytimes.com
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