Alien Species.vp - IUCN

C.R. Veitch and M.N. Clout
As a result of this massive surge of deliberate introductions, and some accidental ones such
as mice (Mus musculus), Norway rats (Rattus norvegicus) and ship rats (R. rattus), the fauna
and flora of New Zealand has been transformed (Table 1).
Table 1 The numbers of species introduced to New Zealand and their present status.
Group Number introduced Number established Number of pests
Vascular land plants 18,830 2020 >300
Freshwater plants 191 52 8
Seaweeds ? 20 1
Terrestrial mammals 55 32 28
Freshwater fish ? 19 9
Birds 145 36 6
Frogs and reptiles ? 4 0
Insects ? ? >350
“Number introduced” is species known to have been imported to New Zealand. “Number established” is species
now with self-sustaining wild populations. “Number of pests” is species which are now listed in legislation or policy
documents as pests or weeds, or which are under some form of control to reduce their numbers.
(After Buddenhagen et al., 1998; Hackwell and Bertram, 1999; King, 1990; McDowall, 1990; Owen, 1997; Veltman
et al., 1996; Williams, 1997; C. J. Green, pers. comm.)
Invasive species legislation
Border controls, as a tax regime, were instigated with early European settlement and became
one of the first New Zealand laws in 1841. Border control actions to manage the importation of
animals and plants began in 1894.
Plants were first legally recognized as weeds in the Orchard and Garden Pests Act of 1896.
The species listed in this Act, and subsequent noxious weeds acts, were plants which were
agricultural pests and it was not until the Noxious Plants Act of 1978 came into being that plants
which were invasive in natural environments were recognized. These Acts all required that land
owners and occupiers took full responsibility for managing the listed species on, and adjacent
to, their holdings. More than 80 species were listed as Noxious Plants.
The Noxious Animals Act of 1956 related to a number of pest animal species but, unlike the
Noxious Plants Act, was largely a measure to allow animal control staff to enter onto private
land to hunt pest animals.
Other Acts related to individual or select groups of species, or to specific actions in relation
to a wide range of species. For example, the Wildlife Act 1953 made it illegal for any person to
liberate any wildlife, including species which were not otherwise protected by law.
The Biosecurity Act of 1993 replaced most of the previous pest control acts and remains in
force today. It requires the management of pest species to be directed by “strategies” which are
drawn up with a prescribed public process. As a result there are a few national strategies, e.g.
bovine tuberculosis, and each Region Council has drawn up one or more strategies for plants
and animals within their region. These strategies may require Region Council staff or
landowners or members of the public to take pest control actions. While there are a number of
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