Battle for our Birds pest control programme to protect native wildlife from rats and stoats this spring has started today with an operation in the Iris Burn valley in Fiordland National Park.
The Iris Burn operation is one of 22 confirmed operations that will use aerially applied 1080 over about 600,000 hectares of conservation land to knock down rising predator numbers fuelled by unusually heavy seeding in South Island beech forests.
The coordinated Battle for our Birds pest control programme is targeted to protect the most at-risk populations of mōhua/yellowhead, kākāriki/parakeet, kiwi, whio/blue duck, kea, kākā, rock wren, giant land snails and native bats at sites across the South Island.
The Iris Burn operation will protect critically endangered long-tailed bat populations along with whio, mōhua, Fiordland tokoeka kiwi, kea and kākā over 11,200 hectares in the Iris Burn valley and adjacent areas including alongside Lake Manapouri.
DOC Fiordland Conservation Services Manager Lindsay Wilson said monitoring results show significant silver beech seed-fall in the area and rapidly rising rat and mice numbers.
“Rodent numbers are already tracking towards levels that will trigger a stoat plague in the next few months—just as our most vulnerable species are nesting and trying to raise their young.
“If we don’t act now to knock back these predators, we could lose species such as long-tailed bat and mōhua from the Iris Burn.”
Today non-toxic cereal bait pellets will be spread across the target area. This “pre-feeding” technique encourages rats to eat the biodegradable poison-laced cereal pellets, which will follow when weather conditions allow.
Ground-based poison bait stations have also been set up over 550 hectares in the Iris Burn valley around long-tailed bat roosts but will not on their own protect bats from predation by rats and stoats, said Wilson.
Stoat trapping along the Kepler Track by the Kepler Challenge Committee also complements the aerial operation.
Planning for up to 30 Battle for our Birds pest control operations covering about 700,000 hectares of public conservation land, mostly in the South Island, has been underway since January following the prediction of a once in 15-20 year beech seeding event.
A close watch is being kept on 6 other target beech forest areas in South Westland, Southland and Fiordland to see whether rodent thresholds are also reached over the coming months and a pest control response is also required.
For more information on DOC’s Battle for our Birds pest control response see: www.doc.govt.nz/battleforourbirds
- The Iris Burn pest control area is home to a number of species vulnerable to predation by rats, possums and stoats, including long-tailed bat/pekapeka, whio/blue duck, mōhua/yellowhead, Fiordland tokoeka kiwi, kea and kākā.
- Aerial 1080 is an effective method of knocking down plague levels of rats and stoats (by secondary poisoning) following a beech mast (seeding), and also possums, before they overwhelm native birds and bats, that are particularly vulnerable during the breeding season and when roosting in holes in trees.
- The pest control operation has two separate phases—the sowing of non toxic “pre-feed” bait, followed by biodegradable poison 1080-laced cereal baits on a separate day.
- The 1080-laced cereal baits will be sown at a rate of 2 kilograms per hectare using GPS-guided feeder systems. The poison content of this bait is 3 grams per hectare.
- 615 bait stations were set up over about 550 hectares in the Iris Burn valley earlier this year to protect long-tailed bats, primarily from rats. Poison in the bait stations in May knocked rats down to very low levels but monitoring since has shown that they have already bounced back to levels that put bats at risk of predation. The bait stations do not effectively target mice and stoats.
- Stringent safety procedures will be in place for the aerial 1080 operation and buffer zones will be in place around significant waterways and other non-target areas.
- Signs with information on the operation and public safety will be in place at the main entrance points to the Kepler Track, the boundary of the treatment area, boat ramps at Manapouri, Supply Bay and Queens Reach, and boat landing sites along Lake Manapouri used by hunters. DOC staff will be at track entrance points and at DOC huts in the area and will clear baits off tracks at the time of the operation.
- The operation will not affect the opening of the Great Walk season on the Kepler Track in October.