This supplied video outlines DOC's efforts to measure the long term effects of 1080 in New Zealand. They claim in one West Coast valley native bird numbers have doubled. (Video first published in January 2019)

New Zealand's native birds are reaping the benefits of aerial 1080 operations.

Numbers of rare and endangered birds have been boosted, including the yellowhead (mohua), blue duck (whio), kea, kaka, rock wren, South Island robin, morepork (ruru), grey warbler, New Zealand falcon (karearea) and kiwi.

SUPPLIED The tiny rock wren lives in the alpine zone, threatened by stoats, mice and harsh winters. In areas where 1080 has been applied, it breeds five times more than otherwise.

In the case of the tiny alpine rock wren, the vulnerable bird raised up to five times more chicks after 1080 treatment than without.

In Kahurangi National Park, the great spotted kiwi has recovered following regular large scale pest control applied over two-thirds of the 452,000 hectare region. Previously, most kiwi chicks were killed by stoats.

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The Department of Conservation monitored the birds before and after the aerial operations. The results are referred to by the Environment Protection Authority which publishes a report every year on the aerial use of 1080.

In 2017, 50 operations were carried out over 875,000 hectares, with 60 per cent due to the DOC "Battle of the Birds" initiative, which was launched because of a high beech forest masting (flowering and seeding event) during the 2016-2017 summer.

SUPPLIED The mohua or yellowhead is a small, insect eating bird which nests in beech tree holes. Mohua nests were twice as successful after 1080 treatment than without.

During a mast year, numbers of rats and mice explode as they feed on the beech seeds, attracting stoats, weasels and ferrets which eat the rats and mice, but also birds.

DOC's results showed birds were not the only species to benefit. So were at-risk populations of longtailed bats, and vulnerable plants such as fuchsia and hall's totara.

The other big user of aerial 1080 was the TBFree programme which aims to curb the spread of TB in cattle. Possums infected with TB pass on the disease to cattle. In 2017, TBfree treated 362,147 hectares of land using the toxin.

DAVID HALLET/STUFF A great spotted kiwi in Kahurangi National Park. Populations of the kiwi are recovering thanks to aerial 1080 treatment.

Before applying 1080, Māori group and hunters were consulted. As a result of consultation with Māori, changes occurred in 28 of the 50 operations. These included boundary changes to exclude sensitive sites, and 15 operations changed from aerial to ground application of 1080 for parts of the treatment area.

Water in catchments was tested for 19 of the operations, with 63 samples taken. None of the 63 samples contained 1080 above the level of detection.

The report said since 2007, more than 1298 water samples from drinking water catchments and other water bodies had been analysed for 1080.

There were 12 reports of non-compliance in 2017, most of them when 1080 was dropped outside the zone they were intended for. None of the reported incidents posed significant risk to public health or the environment.

SUPPLIED The latest report from the Environmental Protection Authority on aerial 1080 says in 2017 there were 12 instances of non-compliance, most of them when 1080 was dropped outside the zones it was intended for, but there was no risk to public health or the environment.

In one, a pilot carrying 1000 kg of cereal pellet baits had to jettison his load prematurely over the Whareorino Conservation area in Waikato when he sensed a mechanical failure in the helicopter.

All the spilt pellets were recovered from the site immediately and disposed of. The local public health official said there was no resulting risk to public health.

The EPA report acknowledges "limitations" with predator eradication methods, including the use of 1080.

"For example, 1080 has reduced the numbers of predators in New Zealand, but it is not target specific. It may result in undesired effects on untargeted species."

It summarises almost 30 research projects on 1080 and on alternative pest control methods. New projects include the development of other types of palatable bait for stoats that are suitable for aerial delivery.