Invasive species in New Zealand

A number of introduced species, some of which have become invasive species, have been added to New Zealand's native flora and fauna. Both deliberate and accidental introductions have been made from the time of the first human settlement, with several waves of Polynesian^[1] people at some time before the year 1300,^[2] followed by Europeans after 1769.^[3]

Clematis vitalba (old man's beard) smothering a cabbage tree (Cordyline australis) in the Port Hills of Christchurch

Almost without exception,^[4][5] the introduced species have been detrimental to the native flora and fauna, but some, such as farmed sheep and cows and the clover upon which they feed, now form a large part of the economy of New Zealand. Possibility of introduced herbivores (deer) to serve as ecological proxies for extinct moa has been questioned.^{[6][7][8][9][10][11][12]}

Biosecurity New Zealand maintains registers and lists of species that are invasive, potentially invasive, or a threat to agriculture or biodiversity.^[13] They also manage a small number of species under the National Interest Pest Responses (NIPR) programme. The rainbow lorikeet is the one animal that has been covered by the NIPR, and was eradicated in 2014. All the other species covered by the NIPR, past or present, are weeds.^[14]

Animal species

Many invasive animal species are listed in schedules 5 and 6 of the Wildlife Act 1953. Those in Schedule 5 have no protection and may be killed. Those in Schedule 6 are declared to be noxious animals and subject to the Wild Animal Control Act 1977. In 2016 the New Zealand government introduced Predator Free 2050, a project to eliminate all non-native predators (such as rats, possums and stoats) by 2050.^[15]

Some of the invasive animal species are as follows.

Mammals See also: Moose § New Zealand Brown rat or Norway rat (Rattus norvegicus) Black rat (Rattus rattus) Kiore (Polynesian rat)[16] Cat Chamois Common brushtail possum (Trichosurus vulpecula)[17][18] Dog European hare European hedgehog[19] European rabbit (Oryctolagus cuniculus)[20] Fallow deer Ferret (Mustela putorius furo)[21] Goat Himalayan tahr Horse (Equus ferus caballus) House mouse (Mus musculus)[22] Least weasel Pig Stoat (Mustela erminea)[17][23] Red deer Rusa deer Sambar deer Sika deer Wallaby Wapiti (elk) Whitetail deer Reptiles Plague skink or rainbow skink (Lampropholis delicata)[24]

Birds Australian magpie Canada goose[25] Cirl bunting Common myna[17] Common redpoll[26] Common starling Dunnock European goldfinch European greenfinch Mallard[27] Mute Swan[28] Rainbow lorikeet Rook Yellowhammer Fish Koi[29] Gambusia affinis[30] Common rudd[31] Catfish Brown trout[32] Invertebrates Argentine ant (Linepithema humile) Asian paddle crab (Charybdis japonica) Asian paper wasp (Polistes chinensis) Australian paper wasp (Polistes humilis)[33] Carpet sea squirt (Didemnum vexillum) Common wasp (Vespula vulgaris) European paper wasp (Polistes dominula)[34] German wasp (Vespula germanica) Varroa mite (Varroa destructor) Spiders As of 18 January 2021[update] there are 73 known introduced spiders, of which 50 are Australian, including Philoponella congregabilis[35] The redback, Latrodectus hasselti, thought to have arrived with a steel shipment in the 1980s[35]

Plant and other non-animal species

The National Pest Plant Accord, with a listing of about 120 genus, species, hybrids and subspecies, was developed to limit the spread of plant pests. Invasive plants are classified as such on a regional basis with some plants declared as national plant pests. Biosecurity New Zealand manages a small number of weeds under the National Interest Pest Responses programme. As of May 2024, NIPR covers nine weeds. Hornwort (Ceratophyllum demersum) was covered until it was eradicated in 2014.^[14] Additionally, the Department of Conservation lists 328 vascular plant species as environmental weeds.^[36]

Some of the better-known invasive plant species are:

• Acacia species (mostly Australian) especially wattle
• Acanthus - bear's breeches
• Agapanthus
• Arrowhead (Sagittaria sagittifolia)
• Arundo donax - giant reed (or elephant grass)^[37]
• Asiatic knotweed (Reynoutria japonica or Fallopia japonica)
• Banana passionfruit
• Blackberry^[36]
• Boneseed (Chrysanthemoides monilifera)
• Boxthorn (Lycium ferossimum)
• Broom (Cytisus scoparius)
• Buckthorn (Rhamnus alaternus)
• Californian thistle (Cirsium arvense)
• Cape sundew (Drosera capensis)
• Cape tulip
• Castor oil plant (Ricinus communis)^[38]
• Caulerpa brachypus^[39]
• Caulerpa parvifolia^[39]
• Christmasberry (Schinus terebinthifolius)
• Climbing asparagus (Asparagus scandens)
• Darwin's barberry (Berberis darwnii)
• Didymosphenia geminata ("didymo" or "rock snot")
• Field horsetail (Equisetum arvense)
• Glyceria maxima, also called Poa aquatica
• Gorse (Ulex europaeus)
• Heather (Calluna vulgaris)
• Japanese honeysuckle (Lonicera japonica)
• Jasmine (Jasminum polyanthum)
• Kahili ginger (Hedychium gardnerianum)
• Lantana camara
• Lodgepole pine (Pinus contorta)
• Loquat (Eriobotrya japonica)
• Lupin
• Madeira vine (Anredera cordifolia)
• Mexican daisy (Erigeron karvinskianus)
• Mexican devil (Ageratina adenophora)
• Mile-a-minute (Dipogon lignosus)
• Mistflower (Ageratina riparia)
• Morning glory (Convolvulus)^[40]
• Moth plant (Araujia sericifera)
• Old man's beard (Clematis vitalba)
• Oxygen weed (Egeria)
• Oxygen weed (Lagarosiphon major)
• Pampas grass (Cortaderia selloana)
• Privet
  • Tree privet (Ligustrum lucidum)
  • Chinese privet (Ligustrum sinense)
• Purple loosestrife (Lythrum salicaria)
• Queen of the night (Cestrum nocturnum)
• Ragwort
• Rhododendron ponticum
• Royal fern (Osmunda regalis)
• Salix cinerea (gray willow)
• Salix × fragilis (crack willow)
• Scotch thistle (Onopordum acanthium)
• Smilax (Asparagus asparagoides)
• Sycamore (Acer pseudoplatanus)
• Tradescantia fluminensis
• Water pennywort (Hydrocotyle umbellata)
• Woolly nightshade (Solanum mauritianum)
• Yellow flag (Iris pseudacorus)

Auckland has been declared to be the weediest city in the world.^[41]

See also

• Fauna of New Zealand
• Invasive species of New Zealand origin

Animals in New Zealand

• Gypsy moths in New Zealand
• Painted apple moth in New Zealand

Plants in New Zealand

• Blue morning glory in New Zealand
• Wilding conifer