Mega mast confirmed for New Zealand forests

Date:  08 April 2019 Source:  Office of the Minister of Conservation

Results from extensive seed sampling across the country in February and March point to the biggest beech mast for more than 40 years with exceptionally heavy seed loads in South Island forests. Rimu forests and tussock grasslands in the South Island are also seeding heavily.

Forest seeding provides a bonanza of food for native species but also fuels rodent and stoat plagues that will pose a serious threat to native birds and other wildlife as predator populations build up next spring and summer.

Eugenie Sage said that new funding of $81.2 million in Budget 2018 over four years had enabled DOC to scale up its predator control programme to respond to the threat posed by the mega mast.

“DOC is planning its largest-ever predator control programme for 2019/2020, at a cost of $38 million, to suppress rats, stoats and possums over about one million hectares or 12 per cent of conservation land.

“This is a step up from the previous largest programme of 840,000 ha in 2016 and 600,000 ha in 2014 and 2017 when there were significant but smaller mast events.

“Responding to the increased threat from introduced predators during such a big mast year is critical if we are to retain our unique native species that set New Zealand apart from the rest of the world.

“If we don’t act, we could lose populations of bird species like our tree-hole nesting orange-fronted parakeet and mohua, and bats, which are so vulnerable to rat plagues.

DOC’s Tiakina Ngā Manu predator control programme, previously known as Battle for our Birds, uses aerially applied 1080 pesticide and large-scale trapping to protect native birds, bats, frogs, lizards and giant land snails at the most important sites across the country.

This work is carefully targeted to sustain the most vulnerable populations of kiwi, kākā, kōkako, kea, whio/blue duck, mohua/yellowhead, kākāraki/orange-fronted parakeet, rock wren/tuke, long and short tailed bats/pekapeka, native frogs and Powelliphanta snails.

DOC’s seed sampling programme involved snipping branches by helicopter from over 8000 beech and rimu trees at nearly 200 sites across the North and South Islands and counting more than three million seed pods from 43,000 samples. More than 1000 tussock plants were also monitored at 63 sites. The estimate of seed-fall this autumn informs predator control planning.

Priority sites for predator control include Kahurangi, Abel Tasman, Arthur’s Pass, Westland, Mt Aspiring and Fiordland national parks, the Catlins and Whirinaki. The programme includes more than 66,000 ha of trapping with the remainder (more than 900,000 ha) aerial 1080 operations.

Aerially applied 1080 is the only tool currently available that can effectively knock down rodents over large areas before they reach plague levels after a beech mast. Numerous studies show that it protects vulnerable wildlife and allows birds to produce more chicks to sustain and build their populations.

While most sites have been confirmed and are at an advanced stage of planning, predator control operations will only proceed at mast sites from May this year if rodents reach levels that pose a threat to wildlife. 

DOC has been consulting with iwi partners, regional councils and other pest control agencies, community groups and neighbouring landowners in recent months as part of its planning.

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