Ship rat eating a fantail chick
Animal pests and predators are a major threat to the survival of New Zealand’s special native flora and fauna. A wide range of techniques and tools are used to control pests, depending on the threats and the terrain.
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The Department of Conservation's (DOC) whole approach is that pest control methods are part of a toolkit and it will select the best option for an individual site.
- In some areas it is essential that aerial 1080 is used, both for cost efficiency and quality of coverage, as well as staff safety. Using aerial 1080 makes it possible to control vast areas of challenging terrain.
- In areas where the costs are much closer and either aerial or ground control can do the job, local staff will select the best method of pest control.
- In areas where ground control is clearly more cost effective and can do the job better, trapping will be used as well as poisons.
DOC's emphasis is on results. If contractors feel they can do the job better with one form of toxin over another, or by sole use of trapping, then DOC will judge them on their performance, including cost and quality.
Ground control is DOC's main approach
Ground control is the use of traps, bait stations or culling. It can prove highly effective where the terrain is suitable and regular checks can be made.
It is DOC's most widely used pest control approach with more than 400,000 hectares under ground control management. Around 80% of the Animal Health Board's operations are ground control.
Ground control methods are precise, but are also labour-intensive and expensive.
Self setting trap
Modern traps are effective and designed to avoid harming native birds if correctly operated. DOC maintains a network of over 180,000 traps and spends more than $5 million per annum on stoat and rat trapping.
Possum fur recovery
DOC also supports possum fur recovery in a number of regions. But even with high fur prices, consistently high numbers of possums are needed to make trapping economic. Also, to ensure the protection of native species, possum numbers must be driven down to very low levels which is uneconomic for a fur recovery industry.
Find out more about possum fur recovery and bounties
Why it's needed
Working on 1080 aerial possum control
Some areas requiring predator control are too remote or too difficult to effectively negotiate on foot, leading to reduced predator kill rates.
In other areas, predator plagues simply overwhelm trap and bait stations, leaving critical populations at risk.
In these circumstances, DOC may apply 1080 baits from the air. This biodegradable toxin is the only effective poison that has been registered for on-going aerial pest control campaigns in mainland New Zealand.
The financial costs of aerial treatment can be significantly less than ground control - in some cases less than a quarter. Nevertheless, DOC applies aerial 1080 over less than 2% (about 150,000 hectares) of the 8.6 million hectares of public conservation land.
For every hectare of aerial treatment, more than 2 hectares are covered by ground control.
Aerial application techniques guided by GPS
DOC has fine-tuned and improved aerial application techniques over many years. Global Positioning Satellite (GPS) technology is now used to ensure baits are accurately and consistently targeted.
Bait quantities reduced
The amount of bait applied has also been greatly reduced. In the early 1990s, up to 18 kg of bait per hectare was being used, whereas sowing rates of 2-3 kg per hectare are now common, thanks to advances in application techniques to improve effectiveness and minimise risks to native species.
Deer repellant can also be used to protect valued recreational species.
One individual 1080 bait is a maximum of 0.15% toxin; the rest is simply a carrot or cereal base. This means that, at today's sowing rates of 2-3 kg of bait per hectare, a treated hectare is covered with less than 1 teaspoon of actual toxin.
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