Page 16 - 2008 NZ Subantarctic Islands

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 culling agent. 1080 has the added value of
being very effective with the 4 species of rats that have

established themselves on the two main islands. The SubAntarctic
islands have been rendered rat-free due to the use of 1080 as
have some other of the islands belonging to New Zealand and

now functioning as preserves. The poison is dropped from the air
and then the kills are monitored by DOC workers on the ground—

both the intended and unintended deaths are counted and
recorded so that improvements in delivery systems can be

researched.

Just for fun, it is good to mention a couple of very ironic
discoveries we made. In 1870 the then Governor of New Zealand
imported 4 species of wallabies from Australia to create a zoo on

a small islet off the North Island. The zoo never had any cages
because it was believed that the wallabies would never swim

across open water and that supposition did turn out to be true.
However, the wallabies found the little island very much to their

liking and found everything they needed for survival and
reproduction. Soon they had eaten all the native species of plants

(they are herbivores) and it became necessary to feed them and
16