Intensive rat control at Falls River, coupled with rat trapping by the Birdsong Trust along the coast, is the first step towards providing a safe corridor for native birds from the high altitudes to the coastal areas of the Abel Tasman.
The Falls River Management Area is an 842 ha site between Torrent Bay and Bark Bay. A network of 841 bait stations to control rat numbers has been installed, complementing the existing stoat trapping network in the area. Bait stations are situated every 50m along tracks 100m apart.
During bird breeding season, tracking tunnels indicate when rat numbers are high. When control is needed the bait stations are filled with either 1080 or diphacinone blocks, to keep rat numbers low to provide a safe environment for the native birds.
The bait stations have a baffle fitted to prevent kea, kaka and weka from accessing the bait. Stations are cleared of bait once the nesting season is over or when rats are deemed to be at an acceptable level.
The Abel Tasman Birdsong Trust runs a network of A24 self-resetting Goodnature traps between Pitt Head and Torrent Bay to provide a safe environment for birds to re-establish and disperse in areas of high public use.
The traps are powered by a CO2 gas canister that can kill up to 24 times per canister. Volunteers check the traps regularly.
Nearly 90% of the Park is now stoat-trapped – a collaboration between Project Janszoon, DOC, the Abel Tasman Birdsong Trust and Air New Zealand.
The majority of traps are DOC 200 traps, but there are five different types of trap boxes in use, some using single traps, others double. We are constantly reviewing how the different trap boxes and different lures perform.
DOC rangers and volunteers from the Abel Tasman Birdsong Trust check and reset the traps every month. It is hard work and they do a great job – they remove and record kills, and add fresh bait.
The stoat lines are positioned 1 km apart with traps set at 100m intervals along the tracks. At this density the network meets best practice standards for stoats, but it is not dense enough for effective rat control.
During a beech mast, when rat numbers soar because of plentiful food, or when possum numbers grow, aerial predator control is the most effective way to control introduced predators.
Given the large area and difficult terrain, aerially applied cereal baits containing biodegradable 1080 pesticide, is sown by helicopter.
1080 is the common name for sodium fluoroacetate, a synthetic version of a naturally occurring toxin found in a range of plants from South America, Africa and Australia. A 2011 Parliamentary Commissioner for the Environment report into the use of 1080 found it was the most effective tool currently available to protect our native wildlife.