New Zealand's Sub-Antarctic Islands - 2008

A little more information on the Aussie brushtails will make it clear why they are impossible to eradicate completely. They are nocturnal and arboreal and therefore very difficult to find. They sleep in tree cavities thus depriving native birds of their usual nesting places. Though they are herbivores in Australia, they have developed a taste for meat in New Zealand so nest robbing for eggs and chicks is now a normal behavior for them. But even if they were not predating birds, they would still be quite destructive as herbivores because the native New Zealand plants did not evolve strategies to avoid or survive mammalian “diners.” Birds, reptiles, and insects in New Zealand often do feed on native plants, but these plants are adapted to the methods of consumption practiced by native creatures. As if devastation of the natural environment were not enough to indict these transplants, they are also vectors of bovine tuberculosis. So not only do conservationists and ecologists rue the presence of these unwelcome immigrants, the dairy farmers are also very sorry they were ever brought over to New Zealand from their own native home. Actually, DOC has many exotics to deal with, thanks to the wholesale importing of mammals that the European settlers accomplished in very short order. A list of animals DOC is currently dealing with include the following: Argentine ants, deer, feral goats, various fish species, feral horses, wallabies, possums, rainbow lorikeets, rats, stoats, ferrets and weasels, tahr and wasps! Of course, the list of exotics is incomplete because we have not even mentioned all the non-native plant types which are out-competing New Zealand’s own species. Needless to add, DOC has a huge and never-endingmission. The major weapon DOC workers employ to try to control the brushtail numbers is a natural plant toxin called 1080; actually it is sodium monofluoroacetate. It has the advantage of being water soluble and biodegradable. But its use is not without controversy since native birds, fish, insects and reptiles do succumb when they ingest it. Many studies have been conducted to make the poison less attractive to any of the native creatures. At present the poison is embedded in a cereal host which has proven to be alluring to the brushtails but relatively uninteresting to birds and other native species. There is a “by-catch” aspect to the strategy, but it is small enough that the scientists believe that this poison is their most effective

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