Poisoning blast may prevent extinctions

Scientist are hopeful the country's largest pest control operation - based around 1080 aerial poisoning - will prevent any endangered bird extinctions this spring.

In the $21-million "battle for our birds" programme, hundreds of tonnes of the contentious poison will be dropped over up to 700,000 hectares between now and Christmas to counter a predicted "biblical" boom in rodent numbers.

The biggest of the 27 operations will be over 270,000ha in Kahurangi National Park, near Nelson. Most 1080 drops will be in the South Island, and cover just a quarter of the 2.8 million hectares of beech forest expected to "mast".

A mast season happens every three or four years, where huge numbers of beech seed trigger an explosion in mouse, rat and stoat numbers. When the seed runs out they turn to native birds and bats.

Such a situation is blamed for the mohua, or yellowhead, being wiped out in the Marlborough Sounds in 2000.

"Hopefully we won't lose anything because we have picked all those sites that have got species that might go extinct if we don't do anything," Department of Conservation scientist Graeme Elliott told a briefing on Tuesday.

He was accompanied by Landcare Research's John Innes and Canterbury University's Dave Kelly.

Such large scale rodent control was new for New Zealand, Dr Elliott said. 1080 had previously been used primarily against possums for Tb control but was found to be very effective against rats, mice and stoats.

They are confident it will work.

Work done in Central Otago's Dart Valley following a mast seeding showed pest numbers could be hammered with 1080 where brodifacoum didn't work.

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Poisoning blast may prevent extinctions