An endangered New Zealand parrot known as the kaka (Nestor meridionalis) has had a much-needed population boost after poisons were used to kill introduced possums, stoats and rodents in Waitutu Forest
Common brush-tailed possums (Trichosurus vulpecula) were introduced to New Zealand from Australia in 1870 for their fur and meat, but they overran the islands, threatening the country's native fauna, which evolved without any mammalian predators. A survey six years ago indicated that so many female kaka were being killed by possums that the birds were at risk of extinction in Waitutu Forest.
To help the parrots, last October the New Zealand Department of Conservation (DOC) dropped cereal pellets laced with a poison known as 1080 over 25,000 hectares of the forest. The results were dramatic. According to the DOC, possum populations within the area have dropped 99.5 percent. Populations of stoats and other rodents, also introduced species, dropped to a level so low, the animals could not be detected "with standard monitoring methods," the DOC reports.
The birds, meanwhile, are thriving in the absence of these predators. The DOC asserts that female kakas have nests full of healthy chicks, making this a record breeding season.
The DOC monitored the area before and after the 1080 drop and found that no birds were killed by the poison. Water samples also showed no signs of the biodegradable poison.
The use of the 1080 toxin has been highly controversial. Also known as sodium fluoroacetate, 1080 is derived from tea and is deadly to most mammals. It has been effective in New Zealand because there are no native mammals for it to kill, but some fear it is too indiscriminate and may pose an eventual danger to humans.
Kakas face threats from several other introduced species, including deer, pigs and wasps. The wasps eat shimmering honeydew, which is a primary source of the birds' diet, providing necessary energy for their breeding periods.
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