The Australian magpie is a medium-sized black and white passerine bird native to Australia and southern New Guinea. Two species, the Black-backed (Gymnorhina tibicen) and White-backed (Gymnorhina tibicen hypoleuca) magpies, were introduced into New Zealand to control pests in pastures but have themselves become an invasive species. The birds can be aggressive and commonly attack humans and occasionally native birds. Cyclists can also be attacked, especially during nesting season of the bird.
Australian magpies in New Zealand Wikipedia
Birds taken mainly from Tasmania and Victoria in Australia were introduced into New Zealand by local Acclimatisation Societies of Otago and Canterbury in the 1860s, with the Wellington Acclimatisation Society releasing 260 birds in 1874. White-backed forms are spread on both the North and eastern South Island, while Black-backed forms are found in the Hawke's Bay region. Magpies were introduced into New Zealand to control agricultural pests, and were therefore a protected species until 1951. It is currently illegal to breed, sell, or distribute the birds within New Zealand.
Due to the lack of scientific study, evidence of the magpie as a predator of native species is often anecdotal. They are thought to affect bird populations such as the tui and kererū, sometimes raiding nests for eggs and nestlings, although studies by Waikato University have cast doubt on this, The same authors suggest that birds avoid areas close to Magpies as they are sometimes attacked by breeding adults, but actual attacks are infrequent.
Pest management is generally done at a regional level in New Zealand and specific Regional Pest Management Strategies (RPMS) are developed. The Biosecurity Act 1993 grants powers to territorial authorities to carry out pest control.
Nine regional councils funded a study by Landcare Research and Waikato University, which concluded Magpies did have a small effect upon other birds but found no evidence that they are serious pests – therefore any control measures would be for other reasons (e.g. conflict with humans).Nelson
The Nelson City Council classes the magpie (both Black-backed (Gymnorhina tibicen) and White-backed (Gymnorhina tibicen hypoleuca)) as a Containment Pest under the Nelson Tasman Regional Pest Management Strategy. This means that the Council will encourage the control of the magpies, including the supply of traps. Under the Biosecurity Act magpies cannot be knowingly sold, propagated, bred, released, or commercially displayed.Wellington
In the Wellington Region magpies are classed as a Site-led pest animal. Under the RPMS for the region magpies are controlled for human health and environmental reasons using a variety of methods.Southland
The Southland Regional Council also includes magpies in their RPMS.