Recently we posted about the problem of increased predator numbers this year, due to predicted heavy beech forest seedfall. We also discussed what this could mean for our endangered native wildlife.
Today, we’re going to have a closer look at what we’re going to do about it…
How does DOC plan to protect at risk populations?
DOC routinely uses traps and other ground based techniques such as bait stations to control rats, stoats and possums. Traps and bait stations will continue to play a significant role in protecting threatened populations such as whio/blue duck in Tongariro, mōhua in the Eglinton valley and kiwi in the West Coast.
However research has shown that rapidly rising rat numbers produced by mast conditions can overwhelm trap networks. Ground based control on its own does not protect threatened bird and bat populations from these predator explosions.
The study of pest control techniques during two localised rat plagues in 2006 and 2009 through DOC’s Operation Ark multi-species protection programme showed that aerial 1080 treatment knocked down rat plagues to near zero levels where ground based methods were not effective on their own.
DOC is prepared to significantly expand its aerial 1080 operations in South Island beech forests in 2014/15 to respond to rising predator numbers.
How effective is 1080 in countering these predator threats?
Permanently eliminating rats and stoats is not currently feasible but research during past mast events has shown aerial 1080 to be the most cost effective tool for quickly knocking down predators over large areas and in difficult terrain.
Aerial 1080 has been shown to suppress rodent plagues to near zero density levels for up to five months. Tracking results indicated it can also kill more than 95% of stoats through secondary poisoning.
For example, aerial 1080 used in the Dart Valley in Fiordland during the rat plague in 2006 resulted in 80% of mōhua surviving whereas in uncontrolled areas only 10% survived.
At Ōkārito on the West Coast aerial 1080 timed to target rats after a beech mast in 2011 doubled the nesting success of kea. Kea pairs in the treated area produced about four chicks each whereas those in the untreated area produced only one due to stoats and possums preying on nests.
As well as being fast and effective over wide areas, aerial 1080 operations cost approximately a third the cost of most ground based alternatives.
How much land managed by DOC is currently treated with aerial 1080?
Pest control cycles vary but over the past five years DOC has treated an average of about 140,000 hectares with aerial 1080 specifically to protect forest ecosystems and native species. This represents about 2% of the 8.7 million hectares of public conservation land which is managed by DOC.
TBfree New Zealand also carries out aerial 1080 operations over an approximate 300,000 additional hectares of public conservation land to protect dairy herds from possums infected with bovine tuberculosis.
Together these combined aerial 1080 programmes cover about 440,000 hectares or approximately about 5% of all public conservation land managed by DOC.
How much more land is DOC preparing to treat with aerial 1080 as part of its Battle for our Birds beech mast response?
The exact scale of DOC’s aerial 1080 programme in the coming year will depend on whether predator populations reach levels which trigger a response but, if required, DOC is ready to increase its aerial 1080 protection in the South Island by about 500,000 hectares.
This together with TBfree New Zealand’s planned programme would result in a total of about a million hectares of public conservation land being treated with aerial 1080 in 2014/15 – about 12% of the land managed by DOC.
To increase its on-going protection for native species DOC is also committed to increasing its aerial 1080 programme by about 50,000 hectares a year for five years. This means DOC itself will be supporting the 2014 beech mast response by routinely treating about 400,000 hectares of public conservation with 1080 by 2019.
What is this expanded programme expected to cost and how will DOC pay for it?
This new Battle for our Birds programme is expected to cost about $21 million over five years. It is a priority project for DOC and will be funded out of the Department’s existing budget using efficiencies gained from improved pest control techniques and co-ordination of operations.