Saturday's protests in a number of Northland centres, including Kerikeri and Kawakawa, against the use of 1080, were part of a national display of opposition, Operation Ban 1080, days before planned drops over Russell Forest and Cape Brett.

Opposition to the use of sodium fluoroacetate is largely based on claims that it kills native animals and birds as well as the pests it targets, and domestic animals, and gets into waterways.

The counter claim is that predator pest numbers are so high, and the damage they are causing so severe, that without knocking them hard some native forests will soon be beyond saving.

Read more: Northland towns join 1080 protest as DoC prepares to use it
Northlanders join nationwide protests against 1080
1080 - Damned if you do and damned if you don't
DOC stands up for 1080 use ahead of protests


Supporters also argue that current methods and strength of 1080 are safer and more effective than in the past.

The protests coincided with ideal spring conditions, with pests hungry after winter and before the native bird breeding season.

Dr Colin O'Donnell, DoC's principal science adviser ecosystems, said 1080 would control introduced pests to the point where forest bird and bat populations could recover.

Rats, possums and mustelids preyed on a wide range of threatened species, including birds, bats, lizards, invertebrates, and even freshwater fish, some of which were heading towards extinction.

Predators were killing more than 50 per cent of breeding female mohua and 80 per cent of breeding female kaka in areas without predator control; only 15 per cent of rock wren nests survived, and annual survival of long-tailed bats was as low as 30 per cent without predator control.

"Such predation rates are unsustainable," Dr O'Donnell said.

"Effectively controlling predators, periodically using aerial 1080, applied at a landscape scale, has led to reversals in the declines of many threatened species in forests.

"For example, in the Landsborough Valley, numbers of native birds have doubled after 20 years of using 1080.


"Numbers of mohua have increased on study lines from 14 in the 1990s to more than 300 today," he said.

"Steady increases in numbers of tui, bellbirds, brown creepers, rifleman, grey warbler and kakariki have also increased, whereas the declines in others (such as kaka) have been halted.

"In the Eglinton Valley, where aerial 1080 is broadcast over more than 26,000ha, numbers of long-tailed and short-tailed bats now have the highest survival rates of bats recorded in the world, and nesting success of kaka was now more than 80 per cent."