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 people at some time before the year 1300, followed by Europeans after 1769. Almost without exception, 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. Registers, lists and indexes of species that are invasive, potentially invasive, or a threat to agriculture or biodiversity are maintained by Biosecurity New Zealand. 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. Some of the invasive animal species are as follows. Mammals Brown rat or Norway rat (Rattus norvegicus) Black rat (Rattus rattus) Kiore (Polynesian rat) Cat Chamois Common brushtail possum (Trichosurus vulpecula) Dog European hare European hedgehog European rabbit (Oryctolagus cuniculus) Fallow deer Ferret (Mustela putorius furo) Goat Himalayan tahr Horse (Equus ferus caballus) House mouse (Mus musculus) Pig Stoat (Mustela erminea) Wallaby Red deer Sika deer Rusa deer Sambar deer Whitetail deer Wapiti (elk) Least weasel Reptiles Plague skink or rainbow skink (Lampropholis delicata) Birds Australian magpie Canada goose Cirl bunting Common myna Common redpoll Common starling Dunnock European goldfinch European greenfinch Mallard Mute Swan Rainbow lorikeet Rook Yellowhammer Fish Koi Gambusia affinis Common rudd Catfish Brown trout Invertebrates Argentine ant (Linepithema humile) Asian paddle crab (Charybdis japonica) Asian paper wasp (Polistes chinensis) Australian paper wasp (Polistes humilis) Carpet sea squirt (Didemnum vexillum) Common wasp (Vespula vulgaris) European paper wasp (Polistes dominula) German wasp (Vespula germanica) Varroa mite (Varroa destructor) Spiders there are 73 known introduced spiders, of which 50 are Australian, including Philoponella congregabilis The redback, Latrodectus hasselti, thought to have arrived with a steel shipment in the 1980s Plant and other non-animal species The National Pest Plant Accord, with a listing of about 120