Why we do this
As expected, in the three years since the last operation, possum and rat numbers have increased in the Hunua Ranges as a result of reinvasion from untreated areas. Repeating the pest control will protect the health of our forest and threatened species, like kōkako, that live within it.
The aerial application of 1080 is a safe and effective method for controlling possums, rats and mustelids. It does not require accessing high value areas by ground, so does not present a risk of spreading kauri dieback disease.
The operation took place across the Hunua Ranges, Waharau and Whakatiwai regional parks and included Department of Conservation (DoC) administered lands including the Mataitai Scenic Reserve and some adjoining private land.
We contacted all landowners or occupiers that lived adjacent to the parkland, and visited many, before the operation.
What is 1080?
1080 is a naturally occurring toxin found in many plants throughout the world. Plants have developed it as a natural defence against browsing mammals.
It is manufactured for use in baits for pest control and is particularly toxic to mammals. This makes 1080 a valuable tool for managing introduced pests in New Zealand, as our only native land mammals are bats.
1080 is highly water soluble and breaks down in the environment. It does not accumulate in the food chain or in soil.
Each pellet is greenish in colour, about 2cm long and the diameter of a 20 cent coin.
1080 is the only toxin currently registered for use on mainland New Zealand as suitable for aerial targeting of possums, rats and - through secondary poisoning - stoats, ferrets and weasels.
Each cereal bait only contains a small amount of toxin, which equates to less than one teaspoon of toxin across a treated hectare.
How the operation was carried out
A satellite navigation system (GPS) and custom-designed bait applicators was used to distribute bait (by helicopter) across the operational area.
To reach as many pest species as possible, we used a two-step method.
- Step one: A non-toxic pre-feed to familiarise pest animals with the cereal baits and make them hungry for more.
- Step two: Application of baits containing the 1080 (sodium fluoroacetate) toxin.
In order to manage such a large area and protect water supply reservoirs, the operational area will be divided into two blocks.
The Cossey and Mangatangi catchments were treated as one block, and the Wairoa and Mangatawhiri catchments treated as another.
Each hectare received around 2kg of cereal pellets. Due to the effectiveness of the 2015 operation, this is is less than the 2.5kg/ha previously used.
The parks were closed during the operation and a track clearance programme carried out before they reopened.
Access to the ranges
The Hunua Ranges parkland was closed during the operation and reopened once the track clearance programme was complete.
Warning signs will remain in place until bait and poisoned animal carcasses have broken down and pose no risk - especially to dogs.
Precautions for people and dogs
Important tips to consider where any form of pest control is carried out:
- Pest control is carried out in parks across New Zealand, and visitors may see traps or bait stations or visit an area that has been treated for pests. Always be aware of pest management programmes, heed warnings and exercise common sense.
- Signs around the operational areas carry important information for all visitors to the parks.
- Don't touch any bait you encounter. Pest animals will quickly start eating bait after it is applied, however, you may see baits within forest areas. Leave bait alone. Supervise children closely, and don’t allow them to pick up or eat baits. Consuming pest management baits could be deadly to a child.
- Supervise dogs at all times. Dogs are susceptible to secondary poisoning, as scavenging is a natural canine instinct. Toxins like 1080 are deadly to dogs, and other poisons or naturally decomposing carcasses can make them very sick. Keep your dog under control at all times, and on a leash where required.
Safety of water supply
Carrying out such an operation in a water catchment area requires careful planning and working closely with Watercare.
Important measures were put in place to ensure the ongoing safety of Auckland's water supply, including:
- no flying over water supply reservoirs
- exclusion zones around reservoirs where no bait will be applied
- using accurate (GPS) technology to apply bait
- returning reservoirs to service only after a rigorous water-testing schedule is complete
- working with landowners to understand drinking water extraction from streams flowing out of the operational area.
In 2011 the Parliamentary Commissioner for the Environment released an independent report endorsing 1080 use.
Download the report from the Parliamentary Commissioner for the Environment website.
DoC also looks after large areas of parkland and uses 1080 application to manage animal pests.
For more on the use of 1080, see the DoC website.