A survey of North Island kōkako following an aerial 1080 predator control operation in the Mamaku Ranges has revealed 71 pairs – up from 44 pairs in 2018, the Department of Conservation (DOC) said today.
The survey, organised by the Mokaihaha Kōkako Trust, which has undertaken extensive ground-based predator control since 2016 to complement three-yearly aerial 1080 operations, also noted 10 single birds compared with eight previously.
DOC Senior Ranger, Rebecca Newland says monitoring showed rat levels had dropped from 42% to zero following the operation.
“There was also a 73% reduction in the number of possums detected,” she said.
“With these kinds of drops in predator numbers, we felt positive kōkako would have a great breeding season and it’s great to see the survey results to back this up.”
Predation by rats, mustelids and possums – along with forest browsing by possums, deer and wallabies – causes threatened native species such as kōkako to decline, the DOC ranger said.
“Rats reinvade the forest every year however possums take longer to return to threatening numbers. Possums eat the eggs of native birds and devastate the canopies of native trees.”
The 1080 operation took place in September last year and covered the Mokaihaha Ecological Area, an area of approximately 2000 ha of unlogged native forest, largely surrounded by pine plantation on the Mamaku Plateau.
It was one of many predator control operations delivered by DOC across the country to protect native forests and wildlife. Ms Newland said it had been deliberately timed to knock back predator numbers ahead of the kōkako breeding season when nesting birds and fledglings become sitting targets for predators.
“1080 is usually applied in cycles. The aerial application covers large areas and effectively reduces predator numbers. The ground control methods are used to keep the predator numbers as low as possible until the next aerial operation is planned.”
“Ground control is typically difficult work and bait stations require a lot of maintenance. We’re grateful to the volunteers in the Mokaihaha Kōkako Trust for all their work to protect and restore the bird’s population in Mokaihaha,” she said.
As part of the survey work, Mokaihaha Kōkako Trust hosted about 40 people from supporting organisations and volunteers so they could hear the haunting call of the kōkako for themselves.
Trust chair, Robin Black was thrilled with the turnout and the results of the survey.
“I have never heard the kōkako in a dawn chorus, but twice this year a pair of kōkako have been heard early afternoon within 50 m of Galaxy Road. The latest field trip introduced me and many others to the sound and sight of kōkako in the canopy.”
“This certainly confirms the benefit of the integrated pest control operation facilitated with financial input from local and central government sources.
“The sharing of knowledge and perspectives in the forest was incredible and, for many, an unforgettable experience,” he said.
North Island kōkako are limited to a few scattered locations where they are generally making a comeback thanks to the concerted effort of community-led predator control, DOC said in a statement.