The Department of Conservation has completed its Battle for our Birds pest control around Mt Stanley in the Marlborough Sounds to protect native wildlife from predator plagues.
The aerial 1080 pest control, carried out on 23 November, is aimed at protecting vulnerable populations of bush robins, weka, rifleman, and giant snails over about 4,000 ha in the Tennyson Inlet Scenic Reserve, Nydia Bay Scenic Reserve and Chance, Penguin and Fairy Bay Scenic Reserve.
Monitoring showed rat tracking levels in the area climbed from 4% in February to 36% in May, 61% in August and 94% in November, just before the pest control. Mice were tracking at 82% in the area in November.
The rising rat numbers have been due to an exceptionally heavy beech seed-fall, known as a mast, providing abundant food. With plentiful rats and mice to feed on, stoats produce more young than usual causing their numbers to explode in summer.
Aerial 1080 predator control knocks down rat numbers. Stoats are reduced through their eating poisoned rodent carcasses.
The pest control began last month with aerial application of non-toxic baits that encourages rats to eat the cereal baits containing biodegradable 1080 pesticide applied on 10 October.
DOC acting Waitohi/Picton Conservation Services Manager Jo Gould said the pest control was aimed at preventing native wildlife suffering heavy losses from the growing predator numbers.
“The pest control has been timed to protect nesting birds so more chicks survive to increase their populations.”
Warning signs advising of the risks of the pesticide are in place at entrance points to the area, including on the Nydia Track and at campsites, jetties and huts.
An aerial 1080 pest control operation in the area last November reduced rats and stoats to undetectable levels and possums to low numbers. Rat numbers subsequently escalated in the area due to the heavy beech seed-fall.
Preliminary research results showed robin nesting success in the operational area last year increased from 22% before the pest control to 78% after it.
The Mt Stanley pest control is among 25 Battle for our Birds operations nationally using aerially-applied 1080 over about 700,000 ha of conservation land to to protect native wildlife from rat and stoat plagues. Aerial 1080 predator control has been completed over more than 80% of the total area so far.
The 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.
Aerial 1080 pest control enables rapid knock down of plague levels of rats and stoats are substantially reduced through eating poisoned carcasses. Ground control on its own cannot protect threatened bird and snail populations from beech mast predator plagues.
The 6 g 1080 baits were sown at a rate of 1 kh per hectare using GPS-guided feeder systems.
Get more information on DOC’s Battle for our Birds pest control programme.