New Zealand’s largest ever pest control operation will be launched this winter in an effort to protect the country's vulnerable birds.

In a pre-Budget announcement at the National Party conference in Auckland today, Conservation Minister Maggie Barry said $20.7 million in funding would be allocated to Battle for our Birds 2016.

It would help to fight back against an expected pest population boom caused by heavy forest seeding, known as a mast.

Barry said Department of Conservation (DOC) scientists had confirmed the heavy fall predicted last year had eventuated.

“We must respond if we’re to protect our native birds and animals from the threat – and the funding will enable DOC to achieve this.”

This autumn about a million tonnes of beech seed will drop to the forest floor, providing a bonanza of food for rats and causing their population to boom.

“As rats increase due to the readily-available food source, so will the number of stoats which feed on rats,” Barry said.

“Once the seeds germinate and the food source disappears in early spring, the plague of millions of starving rats and tens of thousands of hungry stoats will turn on native wildlife, bringing disaster if we do nothing.”

Vulnerable species could be brought to the brink of localised extinction with whole populations wiped out if nothing was done. The pest plague would also kill millions of other birds, native insects, bats and reptiles.

“All the indications are that this mast is on a similar scale to the previous event in 2014, which saw the launch of Battle for our Birds, though with a slightly different distribution as more seed fall is predicted in the southern South Island.”

This year, DOC will ramp up pest control by 500,000ha to cover more than 800,000ha of land.

Aerial drops of 1080 poison will be backed by on-going trapping and ground control programmes.

Pilot projects will also be run to test the effectiveness of using self-resetting traps to keep pests permanently out of an area following a 1080 operation.

“By taking what we’ve learned from our response two years ago we’re able to increase the targeted area, protecting more precious habitat and more bird populations,” Barry said.

“We will prioritise protection of vulnerable great spotted, brown and tokoeka kiwi, kaka, kea, whio/blue duck, mohua/yellowhead, kakariki/orange-fronted parakeet, rock wren, long and short tailed bats and giant snails.

“DOC will monitor the pest situation to determine where best to deploy aerial 1080 – priorities will be Fiordland, Otago, South Westland, North Canterbury, Kahurangi, the lower North Island, Taranaki and Tongariro.”

Research from the 2014 operation showed breeding success rates in areas treated with 1080 were far greater than in areas with no control.

“For example, rock wren raised three times more chicks than birds in an untreated area in 2014-15 and five times more chicks when the birds bred again a year later, which demonstrates ongoing benefits,” Barry said.

“Biodegradable 1080 remains the safest, most efficient and effective method of pest control in the rugged back-country of New Zealand and we must use it if we are to protect our precious native creatures from the effect of the beech mast — we simply can’t allow ill-informed, unscientific campaigns to cause us to back away from what we need to do to save our taonga species.”

However the Green Party believed the spending increase will come at the expense of other DOC operations.

Green Party conservation spokesman Kevin Hague said, while the Government should be commended for spending money on pest control, other parts of the Department of Conservation are likely to make up the shortfall.

He said the National Party is great at talking up projects, but many of those projects have been funded by making continual cuts in the funding of DOC operations.

Hague said, on average, National's funding of conservation has been $50 million less each year than the last Labour Government.