for National Geographic News
When New Zealand split away from the supercontinent Gondwana some 80 million years ago, its flora and fauna were left to develop in isolation.
The result was a virtual Noah's Ark of bizarre animals: Flightless, nocturnal parrots that hike several kilometers at a time; yellow-eyed penguins that nest in forests; and bad-tempered kiwis with skin as tough as shoe leather, poor eyesight, and a highly developed sense of smell.
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Living in a paradise without predators, these odd species thrived. But when the first human settlers, the Maoris, arrived about a thousand years ago, the rats and dogs they brought with them wreaked havoc on the islands' wildlife. Europeans arrived in the early 1800s, bringing with them mustelids (stoats, ferrets, and weasels), cats, and two more species of rats. In addition to the threats posed by newly introduced predators, imported goats, sheep, and cattle competed with the native animals for food.
New Zealand's native bird populations plummeted.
"Land clearance has removed the majority of habitat available," said Doug Armstrong, senior lecturer in wildlife ecology at Massey University in Auckland. "But there would still be habitat to support good populations of all bird species, I think, if it wasn't for introduced predators."
Conservationists working to protect and restore these populations determined that the only way to save New Zealand's threatened bird species was to move them to predator-free offshore islands. Don Merton is a senior technical officer at New Zealand's Department of Conservation. Ha said there have been 198 translocation projects involving 34 bird species to 75 offshore islands since the 1890s.
Creating Predator-Free Environments
Turning an island into a sanctuary is harder than it sounds. One can't just drop off a dozen hihi birds, wish them luck, and hope that they survive.
"The key is to develop a working theory on what caused the original extirpation, [and determine] whether those factors are still operating, and what management is required to have a viable population," Armstrong, the Massey University wildlife ecologist, said.
Before embarking on a translocation project, scientists must first learn everything possible about a target species, from mapping out their historical home range to identifying nesting preferences. Once a species' needs are known, clearing an island of introduced predators and restoring its natural habitat can be a mammoth task. If the population comes from captive stock, the birds must be taught how to survive in the wild.
If the birds are captured in the wild, scientists must ensure that populations are genetically compatible with existing populations and that the original population is not being depleted.
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