Alien Species.vp - IUCN

population is based largely on information gained from the media that are available within the
urban community.
The volume of information, both fact and fiction, about the ongoing effects of invasive
species and their management has been increasing. This information is about both the benefits
and detriments of both the species being controlled and the methods used for that control.
Some examples
1. Border control. For many years New Zealand has had laws and a strong will to control
invasive pests at border control points. People entering the country are not permitted to
bring a wide array of produce, seeds and other items into the country. Recent changes in
global transport and travel, and political willpower, have seriously eroded the ability to
keep invasive species out of the country. Today, due to financial constraints on border
control staff, just one in five of the shipping containers entering the country can be
checked for pests, so containers from “high risk” areas are identified and checked first.
People arriving by air are advised of the pest risks but New Zealand’s national carrier,
Air New Zealand, refuses to show passengers a video prepared by border control officers
on this subject. Other airlines do show this video. At the border, queues are inevitable
and passengers complain if they believe they are being unduly delayed. Often these
complaints are aired in the media and taken heed of by politicians. The need to stop pests
entering the country is of secondary importance to many people.
2. Rabbits. The best known of the early European introductions is the rabbit (Oryctolagus
cuniculus). Captain Cook released some in 1777 (Gibb and Williams, 1990) which failed
to establish, as did other liberations between 1840 and 1860. Liberations between 1860
and 1869 did establish, but the scale of this mistake was rapidly realized as rabbits
became a major invasive pest, and one of the first to be subject to control attempts and
associated legislation. Rabbits were reported as a nuisance in Southland and
Marlborough in 1869 (Miers, 1970) and were recognized by Government in the Rabbit
Nuisance Act of 1882. Control of rabbits over the past 120 years has involved large scale
shooting, trapping and poisoning. It has also involved at least three attempts at biological
control. The first was the introduction of mustelids (stoats, weasels, ferrets) in the 1880s,
the second was the failed attempt to introduce myxomatosis in the 1950s (appropriate
vectors were absent) and the third was the illegal introduction and distribution of rabbit
calicivirus disease (RCD) by farmers in 1997. This followed a Government decision to
defer the introduction of this new disease, which had recently escaped from containment
in Australia. Pastoral farmers in rabbit-infested parts of the South Island were incensed
at this decision and some took things into their own hands, apparently smuggling in the
virus from Australia and distributing it widely. By the time it was detected by officials it
was too late to eradicate it. Owners of pet rabbits were concerned about infection and
conservationists were concerned about the effects on native wildlife of prey-switching
by mustelids and cats. The RCD introduction is an example of a special interest group
bypassing due process and border control laws in their own interests. Paradoxically,
these border control laws are in place primarily to protect the interests of the agricultural
sector.
3. Brushtail possums. The brushtail possum (Trichosurus vulpecula), an Australian
marsupial, is a recognized pest species throughout most of New Zealand. It damages
forest, preys on the nests of native birds and carries bovine tuberculosis. Various
methods (trapping, poisoning, biological control) are used or proposed for possum
control and there is some form of opposition to almost all methods. There is especially
strong opposition from some in the hunting community to the widespread aerial
distribution of baits containing 1080 poison (sodium monofluoroacetate), because this
poison also kills wild deer and feral pigs and is highly toxic to dogs that may scavenge on
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Human dimensions of invasive alien species