26 February 2019

Pest numbers in the Hunua ranges are at an all-time low following a pest control operation completed last year.

In September and October 2018, Auckland Council, in partnership with the Department of Conservation, carried out a pest control operation across 22,000 hectares of forest in the Hunua Ranges.

It involved the aerial application of 1080 to protect this significant forest and its native species, including at-risk kōkako, from pests; particularly possums and rats.

Auckland Mayor Phil Goff says that with the help of Aucklanders who supported the environment targeted rate, huge progress is being made towards a predator-free Auckland.

“We have to eliminate predators to allow our bush and our native birds to regenerate. The impact in the Hunua Ranges in wiping out rats and possums has been impressive and allows our native birds and trees to recover.

“We can see the results in the doubling of the number of kōkako breeding pairs, meaning we now have the fifth largest kōkako population in the country in the Ranges, reducing the risk of extinction of this and our other precious native bird species.”

Impressive results

The operation targets were to get possum densities below three per cent and rat densities below five per cent; meaning that less than three possums were caught, or less than five tracking tunnels had rat footprints, for every 100 traps or tunnel nights.

Deputy Mayor and Franklin ward councillor Bill Cashmore says the post-operation monitoring results have exceeded expectations.

“We’re delighted to report the results for possums was 0.23 per cent and zero per cent for rats. These are incredible results that build on the success of the 2015 operation. It’s a significant reduction in both pest species but particularly rats, which were tracking at 75 per cent ahead of the operation.

“Within the 2000-hectare kōkako management area, which has been monitored twice since the first bait application in September, no possums or rats have been recorded.”

The zero per cent monitoring result for rats does not mean there are no rats remaining, but that across the several hundred monitoring sites no rat prints were detected on any of the inked tracking cards.

“These results are hugely significant and again show 1080 is currently our best tool to protect our ranges. We acknowledge the support of the surrounding community, particularly landowners who made the work possible," says Mr Cashmore.

The treatment area expanded as a result of the recently introduced Natural Environment Targeted Rate.

“Thanks to Aucklanders supporting this new rate, staff were able to treat more land and increase the use of ground methods additional to the aerial operation. This will significantly reduce the re-invasion risk for pests into the park, and benefit landowners who are wanting to reduce the impact of these pests on their own properties."

DOC and Auckland Council collaboration

“This operation provided a great opportunity for DOC and Auckland Council to work together to benefit the native forest and wildlife in the Hunua Ranges Regional Park and neighbouring DOC reserves,” says DOC Auckland Operations Director Andrew Baucke.

“We work hard to protect our precious native species so to see rat and possum numbers at an all-time low in the Hunua Ranges is absolutely terrific.

“Aerial operations are the only way to access this steep and rugged terrain, at present, and an operation like this gives our native taonga the best chance to thrive.”

Kōkako population thriving

Environment and Community Committee Chair, Councillor Penny Hulse says one of the success stories of the Hunua pest control programme has been the resurgence of the kōkako population within the forest.

In 1994, only one breeding pair of kōkako remained in the Hunua Ranges. At the end of last year, a census carried out within the Kōkako Management Area counted 106 pairs, nearly double the 55 pairs that were counted in 2014.

“This shows how effective pest control can save a unique species from near extinction. This is why we must continue to do it. The kōkako are now here for future generations as a unique part of the Hunua ecosystems,” says Ms Hulse.

“We have also recorded our best fledgeling result from our six monitored pairs with 18 chicks fledged. These are remarkable results that are a direct credit to the hard work put in over the last 24 years.”

A further census of the wider Hunua Ranges, outside of the managed area, is planned for April.

Ongoing safety measures

While the parklands reopened in early October, visitors are reminded to remain vigilant while the caution period is in place.

• Signage remains in place to remind people 1080 has been used in the area. This is an operational requirement of using a toxin like 1080 and a good reminder to visitors they may encounter bait that hasn’t yet broken down or pest animal carcasses.

• Dog owners should continue to take care, both inside and close to the operational area, to make sure dogs are not allowed to scavenge carcasses. Children should also be carefully supervised.
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Visit the Auckland Council website for more information on the entire project, including why the council carried it out and how.

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