Alien Species.vp - IUCN

Human dimensions in the management of
invasive species in New Zealand
C.R. Veitch and M.N. Clout
Abstract
New Zealand has been only recently populated by humans, but thousands of species of
plants and animals have been introduced, with nearly 700 of them now considered to be
pest or weed species. Strong legislation exists to limit new introductions and to enable
control of existing infestations. Attitudes to invasive alien species vary between different
public groups and between different groups of species, tempered by management costs
and by official policies. Public perceptions of invasive species come either from direct
experience of impacts of these species or from the media and other sources of information.
Introduction
Knowledge of the pre-human condition of New Zealand has an important bearing on an
appreciation of the subsequent impact of introduced species, particularly the perception of
whether they are invasive or benign. Before human settlement the country was mainly a
forested land, with bats as the only land mammals. Forest originally covered about 80% of the
land but by the time of European arrival that was reduced to about 53% and today comprises
about 21.6% of the land cover (Cumberland, 1966).
The Pacific rat (Rattus exulans) was the first invasive species introduced to New Zealand,
probably around AD 50–150, during transient visits by Polynesian visitors. These alien
mammals did not reach offshore and outlying islands until after permanent Polynesian
settlement of the country occurred, around AD 1300 (Holdaway, 1999). Circumstantial
evidence indicates that the Pacific rat, alone, caused extinction or depletion of several bird,
lizard and insect species, and significant modification of floral assemblages (Holdaway, 1989).
The first European contact with New Zealand was that of Captain James Cook in 1769. From
then onwards many plants and animals were deliberately and accidentally introduced to the
country. Colonists from the United Kingdom brought with them, or later imported, a huge array
of species to make the land “more like home”.
From the early 1860s “Acclimatisation Societies” were established in New Zealand to
promote the introduction of exotic animals for hunting, and plants for propagation to
supplement existing vegetables, fruits, flowers and shrubs (McDowall, 1994). Major reasons
for the introductions were nostalgia – a desire to be reminded of Britain, from which the settlers
had emigrated – and sport – mammals and birds that could be hunted. In addition to these
formally “planned” introductions, many other species (especially plants) were brought to New
Zealand by colonists during the nineteenth and twentieth centuries. Hundreds of species of
plants, birds and mammals were introduced, many of which became established.
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